Source: IOWA STATE UNIVERSITY submitted to NRP
EFFECTS OF LIPIDS ON PHYSICAL PROPERTIES, DIGESTIBILITY, AND NUTRITIONAL BENEFITS OF STARCHY FOODS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
AFRI COMPETITIVE GRANT
Reporting Frequency
Annual
Accession No.
0219419
Grant No.
2009-65503-05798
Cumulative Award Amt.
$473,870.00
Proposal No.
2009-02322
Multistate No.
(N/A)
Project Start Date
Sep 1, 2009
Project End Date
Aug 31, 2014
Grant Year
2009
Program Code
[93430]- Improving Food Quality and Value
Recipient Organization
IOWA STATE UNIVERSITY
2229 Lincoln Way
AMES,IA 50011
Performing Department
Food Science & Human Nutrition
Non Technical Summary
The long term goal of this study is to identify combinations of starch and selected lipids after proper processing to produce foods that are digested at a slower rate to improve human health and reduce obesity and metabolic-related illness. Preliminary studies conducted in the investigators' laboratories showed that the starch digestive rate is reduced in the presence of stearic acid and triglycerides. Humans fed bread made from high amylose cornstarch fatty acid complex significantly reduced blood glucose and insulin responses, and rats fed with a similar starch fatty acid complex diet showed reduction in precancerous lesions (Mucin Depleted Foci) from 3.5 to 0.3. All these results showed significant potential health benefit provided by complexes between starch and fatty acids. This proposed study is aimed at understanding the mechanism of starch lipid interactions and to identify which lipids have the greatest impact on the physical properties and digestive rate of the starch and how processing techniques affect the results. Using the results obtained from the in vitro study of Objective 1, we will select representative processed starchlipid diets for humans (Objective 2) and rat feeding studies (Objective 3) to reveal health benefits of starch lipid mixtures on the glycemic response and colon health. Objectives of this proposed study are 1. Establish a systematic understanding of how lipid molecules with different structures interact with starch molecules and how the interactions affect the swelling, dispersion, viscosity and in vitro enzyme digestibility of the starch. 2) Investigate how the lipid interactions with starch affect the in vivo enzyme hydrolysis rates of starch and the bioavailability of starch in humans, and 3) Examine effects of the starch lipid complex bioavailability on colon health and colon cancer prevention in rats. We expect the outcomes of the study will help the food industry and general public select proper food ingredients and processing techniques to improve human health, reduce obesity and other metabolic syndromes, and prevent colon cancer.
Animal Health Component
30%
Research Effort Categories
Basic
60%
Applied
30%
Developmental
10%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
5011510100020%
5021510100030%
5021510101050%
Knowledge Area
501 - New and Improved Food Processing Technologies; 502 - New and Improved Food Products;

Subject Of Investigation
1510 - Corn;

Field Of Science
1010 - Nutrition and metabolism; 1000 - Biochemistry and biophysics;
Goals / Objectives
The long term goal of this study is to identify combinations of starch and selected lipids after proper processing to produce foods that are digested at a slower rate to improve human health by reducing obesity, metabolic related illnesses, and improving colon health. Objectives of this study are to understand mechanisms of starch interactions with lipids of different structures and polarity, including free fatty acids, triglycerides, and phospholipids, and how the starch lipid interactions affect the properties, quality, and processing ability of foods, enzyme digestibility of the starch in the food, and impacts of the starch lipid complex on colon health. Specific objectives of this study are: 1. Establish a systematic understanding of how lipid molecule structures affect interactions with starch molecules and how these interactions affect the swelling, dispersion, viscosity and in vitro enzyme digestibility of the starch. 2. Investigate how the lipid interactions with starch affect the in vivo enzyme hydrolysis rates of starch and the bioavailability of starch in humans. 3. Examine effects of the starch lipid complex bioavailability on colon health in rats. The results obtained from this study are expected to enable us to develop economical approaches to improve human health by properly formulating lipids and starch in the daily diet to reduce the digestive rate of starch in food. Slow digestion of starch in food reduces the blood glucose level and insulin response, which is useful for diabetic patients and people at risk for Type 2 diabetes. Slower digestion of starch in food ingested is expected to prolong satiety after consumption of a meal and reduce the amount of food consumed which will, in turn, reduce obesity caused by cycles of hyper and hypoglycemic responses. Results obtained from this study will also teach us which kinds of starch lipid complex can reduce the formation of cancer in the colon. Results on physical property changes caused by interactions of starch with different lipids, such as swelling power of starch granules and viscosity of starch pastes will be useful for the food processing industry to reduce extrusion viscosity. A better understanding of the interaction between starch and lipids may allow the food processing industry to shorten the required storage time of crops, such as oats, corn, and wheat, for use in extrusion processing.
Project Methods
Tapioca, waxy corn, normal corn, and high-amylose corn starches, having different structures, will be used for the study. These starches will be mixed with selected lipids, including free fatty acids of different degrees of saturation, monoglycerides, phospholipids, triglycerides (e.g., corn oil, soybean oils, sunflower oil, and palm oil) and subjected to batch, oven, amylograph, or extrusion cooking. Cooked starch lipid mixtures will be subjected to physical property analyses, including contents of free and complexed lipid, thermal properties, crystalline structures, degree of the helical complex formation between starch and lipids, viscosity and pasting properties, morphology of the samples using light and confocal laser scanning microscopy, and in vitro enzyme digestibility of starch. The results will provide information about combinations of starches and lipids and processing techniques that produce slowly digestible starch. A human feeding study will be conducted using food containing starch lipid complexes identified in objective 1, including a cornstarch stearic acid complex and a cornstarch corn oil mixture, which will be compared with native cornstarch alone. Thirty healthy human subjects, half men and half women, will be recruited for this study. After an overnight fast each subject will consume the control or experimental starch food containing 50 g of starch on a single day, with a one week washout period between treatments. Blood samples will be collected from the subjects every 15 minutes beginning 15 minutes before to 120 minutes after ingesting the test foods, as well as at 4 and 8 h after test food ingestion. Breath gases will be collected up to 8 h after test food ingestion to assess starch fermentation. Radioopaque markers will be given with the test food and feces collected until 90% of the markers are excreted. Fatty acids will be measured to assess gut fermentation of the starches. The plasma glucose concentrations are measured using a glucose oxidase analyzer and the plasma insulin concentrations are determined using an ultrasensitive insulin ELISA kit. Effects of the starch lipid complex on colon health will be conducted in a study using the F344 rat colon carcinogenesis model induced by azoxymethane (AOM). Rats will be obtained at 5 weeks of age. Following one week of feeding the control diet, they will be treated with two weekly injections of 15 mg AOM per kg body weight. Beginning three days after the final AOM treatment, groups of AOM treated (30 rats) or control (saline injected, 10 rats) rats will be fed experimental starch lipid complex diets or the control cornstarch diet. At the end of 38 weeks of receiving the experimental diet, surviving rats will be sacrificed by cervical dislocation. Colon contents will be removed, weighed and extracted for butyrate and other fatty acids analysis. Colons will be examined grossly and histologically for development of precancerous lesions and benign or malignant colon tumors. Tumors will be scored for their location and number and the development of colon lesions will be correlated with diet composition and fatty acid analysis.

Progress 09/01/09 to 08/31/14

Outputs
Target Audience: Nutritionists; dietetics; the food industry; consumers who are interested in intervention of Type-2 diabetes, overweight, and colon cancer; grain processors; and the animal feed industry. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Over the course of the project, six graduate students were involved in the project and trained. How have the results been disseminated to communities of interest? The list of publications and presentations shows the means of dissemination to the communities. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Studies conducted in this research project demonstrate that lipids, including corn oil, fatty acids, and lecithin, interact with normal and high-amylose starch but little with waxy starch to reduce the viscosity, pasting properties, and digestive rate of starch. Resistant starch and slowly digestible starch in the diets reduce post-prandial glycemic response and insulin secretion, which can prevent Type-2 diabetes. Resistant starch, which cannot be digested in the small intestine, is passed on to the colon, used by certain microorganisms to grow, and change microbiota population. Specific accomplishments under each objective are listed as follows: Objective 1. Establish a systematic understanding of how lipid molecule structures affect interaction with starch molecules and how these interactions affect the swelling, dispersion, viscosity and in vitro enzyme digestibility of the starch Impacts of different lipids on digestive rates and physicochemical properties of starches and the mechanism of interactions were studied. Comparing with the hydrolysis rate of normal corn starch cooked alone, that of the starch cooked with lipids displayed ca. 20% reduction. Tapioca starch and high-amylose maize starch followed the same trend. That of waxy corn starch, however, was not affected by lipids. 13C- nmr results revealed a helical complex formation between the starch molecules and fatty acids from lipids. Using the principle, rice was cooked using different methods to prepare steamed rice, fried rice, and rice pilaf. Starch hydrolytic-rates of these cooked rice showed an order of steamed rice > rice pilaf > fried rice. Up to 36% reduction in the starch hydrolysis rate was observed between the fried and the steamed rice. Thermal and pasting properties of starch were also affected by the presence of lipids. Adding lipids reduced the retrogradation rate of normal corn starch (NCS) because of amylose-lipid complex (ALC) formation. The reduced swelling resulting from ALC, in turn, decreased the digestibility of starches. Pasting temperature of normal corn starch decreased with the presence of soy lecithin. A paste of tapioca starch alone cannot develop a gel. After premixing with selected lipids, tapioca starch paste can form a gel, resulting from ALC formation. Resistant starches (RS), including high-amylose corn starch (HACS), octenyl succinate (OS)-HACS, and stearic acid (SA)-HACS, were developed for human and animal feeding studies. Both in vitro and in vivo digestibility of the RS were studied to understand the mechanisms of their enzyme digestibility. For animal feeding studies, diets containing 55% normal corn starch (NCS), HACS, OS-HACS, and SA-HACS were prepared. Resistant-starch contents of the diets and rat feces were collected and analyzed. Results showed that RS contents of rat feces fed with HACS and SA-HACS were high after one-week feeding but decreased after prolonged feeding periods, whereas, that of feces fed with OS-HACS remained high after nine-week feeding. Results of the RS content of a food sample, containing cross-linked starch or SA-HACS, obtained between using the AOAC Method 991.43 (with B. licheniformis α-amylase, BA) and the Englyst method (with porcine pancreatic α-amylase, PPA) were significantly different. A mechanistic study on enzymatic hydrolysis of starch granules using these two enzymes showed that these two enzymes hydrolyzed starch granules in different ways. BA attacks the surface of starch granules, whereas PPA hydrolyzes starch by boring a channel into the granule because of different binding size and reaction patterns of the enzymes. Objective 2. Investigate how the lipid interactions with starch affect the in vivo enzyme hydrolysis rates of starch and the bioavailability of starch in humans. Short term human trial of SA-HACS effects on human physiological responses including gut fermentation was accomplished. SA-HACS was compared with its parent HACS for physiological effects in healthy humans. In a randomized blinded crossover study after a 10-h fast, 30 participants ate crackers providing 50 g carbohydrate and approximately 6% (control starch crackers, NCS), 24% (high amylose crackers, HACS) and 58% (stearic acid-high amylose crackers, SA-HACS) digestion resistance as measured using the AOAC method 991.43. Cracker types were given solely as a test meal once a week over a period of 3 weeks. Glucose, insulin, and fermentation responses were evaluated. Blood glucose area under the curve (AUC) was not different between HACS and SA-HACS; both produced lesser AUC responses than NCS. Reduced insulin AUC was found only in HACS when compared to NCS. Postprandial glucose (PPG) response was similar between SA-HACS and HACS. Only HACS significantly suppressed blood insulin response compared with NCS. Fermentation, assessed by breath hydrogen, was greater after ingestion of SA-HACS than after eating HACS or NCS. Fermentation assessed by fecal short chain fatty acid (SCFA) contents over 2 days after starch feeding was not different between cracker types. Gastrointestinal bloating was significantly greater with SA-HACS than with HACS or NCS, but the symptom score was in the range of mild discomfort only. SA-HACS was shown to be a well-tolerated fermentable digestion-resistant starch that diminished blood glucose response in a test meal compared with conventional starch. This study showed that SA-HACS has promise as a fermentable resistant starch used in food to enhance satiety based on previous studies of effects of fermentable resistant starches on satiety hormones such as polypeptide YY. It may also be useful to control blood glucose levels for individuals such as those with type 2 diabetes. Objective 3. Examine effects of the starch lipid complex bioavailability on colon health in rats. A study of the impact of control NCS, HACS, and SA-HACS on colon cancer was accomplished using the A/J mouse. Based on our earlier validation study and on our preliminary study assessing aberrant crypt preneoplastic lesions, a dosage of 7.5 mg azoxymethane (AOM)/kg body weight was administered 4 times at weekly intervals to induce colon cancer. Research was then conducted to examine impacts of diets containing 55% starch (by dry weight) of control NCS, HACS and SA-HACS on the development of AOM-induced colon cancer. The NCS and HACS were used as the controls. After being injected with AOM or saline solution (control) while being fed the NCS diet the rats were fed as described above for 29 weeks beginning 3 days following the last AOM treatment. After the rats were sacrificed the distal colons were sent for preparation of H&E slides for pathological evaluation. In contrast to the results observed in ours and other laboratories short term studies (~10 weeks) with feeding RS where a dramatic increase in cecal tissue and content weight are observed and a striking reduction in cecal content pH is seen, in this study after 29 weeks on a RS diet the cecal weights and contents were only modestly increased in the mice fed the HACS diet irrespective of AOM treatment and there was no increase in the size of the colons on the mice fed the SA-HACS diet. Similarly, cecal content pH values were not altered by the HACS or SA-HACS diets compared with control values. On necropsy we observed no gross lesions in the colons of the control or carcinogen treated mice. Before the kill and at the time of necropsy we observed either/or blood in the feces/intestines, blood in the cecum or apparent obstruction in the cecum of AOM treated mice fed the control diet (1), HACS diet (3) and SA-HACS diet (2). We await results on pathology. The observations showing modest or no impacts of the resistant starches on cecum tissue or content weights and cecum pH suggest that the mouse may have adapted to the resistant starches in the long term studies.

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: T. J. Anderson, Y. Ai, R. W. Jones, R. S Houk, J. Jane, Y. Zhao, D. F. Birt, and J. F. McClelland. Analysis of Resistant Starches in Rat Caecal Contents Using Fourier Transform Infrared Photoacoustic Spectroscopy. 246th American Chemical Society National Meeting & Exposition, Indianapolis, IN. Sept. 8-12, 2013.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: S. Moore, Y. Ai, and J. Jane. In vitro and in vivo digestibility of resistant starch. Plenary lecture presented at Starch Update Conference. Bangkok, Thailand, Nov. 21-22, 2013.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: J. Jane. Structure and digestibility of selected starch. 2013 Belfort Lecture at the Whistler Carbohydrate Center Technical Conference, Purdue University, West Lafayette, IN, May 8, 2013.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Zhao, Y., Ai, Y., Li, L, Jane, J-L., Hendrich, S., and Birt D.F. Inhibition of Azoxymethane-induced Preneoplastic Lesions in the Rat Colon by a Stearic Acid Complexed High-amylose Cornstarch using Different Cooking Methods and Assessing Potential Gene Targets. Journal of Functional Foods 6:499-512.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Anderson, T., Jones, R., Ai, Y., Houk, R. S., Jane, J., Zhao, Y., Birt, D., McClelland, J. (2014). High Resolution Time-of-Flight Mass Spectrometry Fingerprinting of Metabolites from Caecum and Distal Colon Contents of Rats Fed Resistant Starch. Analytical and Bioanalytical Chemistry 406:745756. Published online 2013, DOI 10.1007/s00216-013-7523-8
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Birt, D.F., Boylston, T., Hendrich, S., Jane, J.-L., Hollis, J., Li, L., McClelland, J., Moore, S., Phillips, G.J., Rowling, M., Schalinske, K., Scott, M.P., Whitley, E.M. Digestion resistant starch: Promise for improving human health. Advances in Nutrition 4:587-601, 2013.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Nelson, B., Cray, N., AI, Y., Jane, J., Birt, DF, Effect of dietary resistant starch on the inhibition of preneoplasia in azoxymethane-induced A/J mouse model Experimental Biology 2014, San Diego, CA, April 26-30, 2014 (Presented by Suzanne Hendrich).
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: T. J. Anderson, Y. Ai, R. W. Jones, R. S Houk, J. Jane, Y. Zhao, D. F. Birt, and J. F. McClelland. (2013). Analysis of Resistant Starches in Rat Caecal Contents Using Fourier Transform Infrared Photoacoustic Spectroscopy. Journal of Agricultural and Food Chemistry 61:1818-1822.
  • Type: Book Chapters Status: Published Year Published: 2013 Citation: J. Hasjim, Y. Ai, and J. Jane. Novel applications of amylose-lipid complex as resistant starch type 5. In "Resistant Starch: Sources, Applications and Health Benefits". Ed. C. Maningat and Y. Shi. (2013), IFT Press, Wiley Blackwell, pp 79-94.
  • Type: Book Chapters Status: Published Year Published: 2013 Citation: H. Jiang and J. Jane. Type 2 resistant starch in high-amylose maize starch and its development. In "Resistant Starch: Sources, Applications and Health Benefits" Ed. C. Maningat and Y. Shi. (2013), IFT Press, Wiley Blackwell, pp. 23-42.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: M. O. Reed, Y. Ai, J. L. Leutcher, and J. Jane. 2013. Effects of cooking methods and starch structures on starch hydrolysis rates of rice. Journal of Food Science 78:H1076-1081.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Y. Ai, Y. Zhao, B. Nelson, D. Birt, T. Wang, and J. Jane. (2014) Characterization and in vivo hydrolysis of amylose-stearic-acid complex. Cereal Chemistry 91:466-472.
  • Type: Journal Articles Status: Submitted Year Published: 2014 Citation: T. J. Anderson, Y. Ai, R. W. Jones, R. S Houk, J. Jane, Y. Zhao, D. F. Birt, and J. F. McClelland, Measurement of resistant starches in rat cecal contents using fourier transform infrared photoacoustic spectroscopy. Submitted to ACS monograph titled Instrumental Methods for the Analysis of Bioactive Molecules.
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2015 Citation: S. A. Moore, Y. Ai, F. Chang, and J. Jane. (2015) Effect of alpha-amylase hydrolysis patterns on analysis of resistant-starch contents. Carbohydrate Polymers. 115:465-471.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2011 Citation: Y. Ai, J. Leutscher, Y. Zhao, D. Birt, T. Wang, and J. Jane. Effects of lipids on physical properties, digestibility and nutritional benefits of starchy foods. Annual meeting of IFT, New Orleans, LA, June 11-14, 2011.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2011 Citation: J. Hasjim, Y. Ai, S. Setiawan, S.-O. Lee, S. Hendrich, Y. Zhao, D. Birt, and J. Jane. The health benefits of resistant starch type 5. Annual meeting of IFT, New Orleans, LA, June 11-14, 2011.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2011 Citation: Y. Ai, Y. Zhao, D. Birt, T. Wang, and J. Jane. In vivo digestibility of amylose-stearic acid complex in rats. American Association of Cereal Chemists International annual Meeting, Palm Springs, CA, Oct. 15-19, 2011.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2011 Citation: J. Jane. Structures and properties of resistant starch and its health benefits. A plenary lecture to the 2nd EPNOE International Polysaccharide Conference, Wageningen, the Netherlands, August 29  September 2, 2011.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2011 Citation: J. Jane. Structures and applications of Type-2 and Type-5 resistant starch. An invited lecture to Starch Roundtable Conference, Palm Springs, CA, October 12-14, 2011.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2011 Citation: J. Jane. Resistant starch and health benefits. A plenary lecture, at the Starch Update Conference, Bangkok, Thailand, November 9-10, 2011.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: Y. Ai, J. Leutscher, B. Nelson, D. Birt and J. Jane. Impacts of lipids on physical properties, enzymatic hydrolysis, and nutritional benefits of starchy foods. IFT Annual Meeting, Las Vegas, NV, June 25-28, 2012.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: M. Reed, Y. Ai, J. Leutcher, and J. Jane. Effects of cooking methods and rice structures on starch hydrolysis rates. IFT Annual Meeting, Las Vegas, NV, June 25-28, 2012.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: M. Reed, E. Whitley, and J. Jane. Structure and microscopy of resistant starch bread rolls. Corn Utilization and Technology Conference, Indianapolis, IN, June 4-6, 2012.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: S. Moore, Y. Ai, and J. Jane. Enzyme digestibility of resistant starch. Symposium on Resistant Starch and Health. Ames, IA, May 14-16, 2014.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: J. Jane. Advances on understanding of structures and enzyme digestibility of resistant starch. Keynote lecture presented at the 10th International Conference on Polysaccharides-Glycoscience, Prague, Czech Republic, October 22-24, 2014.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: Y. Ai, B. Nelson, D. F. Birt, and J. Jane. Digestion and potential colon health benefits of octenyl succinic starch. Annual Meeting of American Association of Cereal Chemists International. Hollywood, FL, Sept 30  Oct. 3, 2012.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: J. Jane. Resistant-starch formation in high-amylose maize starch. A seminar presented at Kohn Kaen University, Thailand, January 18, 2012.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: J. Jane. Novel resistant starch and health benefits. G. Malcolm Trout Visiting Scholar Lecture, presented at Michigan State University, March 14, 2012.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: J. Jane. Development of resistant starch to improve health. A public lecture presented at University of Campinas, Brazil, April 2, 2012.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: J. Jane. Resistant starch, slowly-digestible starch, and their health benefits. A keynote lecture presented at the 2nd Chinese Starch Roundtable Conference, Guangzhou, China, Nov. 5-6, 2012.


Progress 09/01/12 to 08/31/13

Outputs
Target Audience: Food and nutritional scientists. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Haugabrooks, E. Ph. D. student in Toxicology, Iowa State University, was mentored as a part of this project, graduation in Dec 2013. Ai, Y. Ph. D. student in Food Technology, Iowa State University, was mentored as a part of this project, graduation in Dec 2013. Nelson, B. M.S. student in Toxicology, Iowa State University, was mentored as a part of this project, graduation in Dec 2013. Moore, S., M.S. student in Food Technology, Iowa State University, was mentored as a part of this project, graduation in Dec 2013. How have the results been disseminated to communities of interest? Publications in the scientific literature, presentations at scientific meetings and dissertations as indicated in the "Products" section, and Diane Birt presented on the potential health benefits associated with resistant starch in grains at the Kellogg Scientific Advisory Board in Battle Creek, MI, on November 11, 2013. What do you plan to do during the next reporting period to accomplish the goals? Complete the ongoing study of the impact of dietary resistant starch (HA7 and RS5) compared with control starch (CS) on colon cancer development in mice and complete publications and presentations of the original research.

Impacts
What was accomplished under these goals? Objective 1: Major activities completed with significant results achieved: Because current methods available for dietary fiber (DF) analysis often give contradictory resistant starch (RS) contents, we analyzed a variety of resistant starches differing in botanical source and chemical modifications using methods commonly employed in the food industry, Association of Official Analytical Chemists (AOAC) Methods 991.43 and 2002.02, and the method described by Englyst (1992), and performed mechanistic studies to better understand reasons for these differences. The widest differences were found in phosphate cross-linked wheat starch (FibersymTM, MGP Ingredients, Atchison, KS), and high-amylose maize starch complexed with stearic acid (RS5), which had very high RS contents when analyzed using AOAC Method 991.43 (90.6 and 65.3% RS, respectively) but comparatively lower RS contents using AOAC Method 2002.02 (49.8 and 27.95% RS, respectively), and the Englyst method including the cooking step (21.2 and 28.3% RS, respectively). However, RS contents measured in RS Type 3, retrograded starch, were very similar regardless of the method used. Because cooking alone was not sufficient to explain measured differences in RS contents, we hydrolyzed raw starches with equal activity of α-amylase enzymes used for DF analysis, namely that of Bacillus licheniformis (BL, AOAC Method 991.43) or from porcine pancreas (PPA, other methods), with low doses up to 84 h. In contrast to native wheat starch, BL was unable to hydrolyze the cross-linked FibersymTM even after 84 h. Changes in starch granule morphology of some native (green banana, wheat, potato) and modified (FibersymTM) starches due to hydrolysis suggested that a key difference in the mechanism of starch hydrolysis and number of glucose-binding subsites in these enzymes, i.e. random attack by BL with nine subsites compared with multiple attack by PPA with five subsites, were responsible for differences in observed RS contents. Restriction of available binding sites free of chemical modification was thus proposed as a cause of very high RS contents observed in modified starches like FibersymTM and RS5. Key outcomes or other accomplishments realized: In using several methods to analyze RS content of starches it was found that the assays gave very similar RS values for Type 3 (retrograded resistant starch) but very different RS values were obtained for phosphate cross-linked wheat starch and high-amylose maize starch complexed with stearic acid (RS5). Follow-up studies revealed that a limited number of binding sites free of chemical modification was thus proposed as a probable reason for very high RS contents observed in modified starches such as phosphate cross-linked wheat starch and RS5. Objective 2: Major activities completed: Stearic acid-modified digestion-resistant starch (RS5) was compared with its parent high amylose starch for physiological effects in healthy humans. In a randomized blinded crossover study after a 10-h fast, 30 participants ate crackers providing 50 g carbohydrate and approximately 6% (control starch crackers, CS), 24% (high amylose crackers, HA) and 58% (stearic acid-high amylose crackers, RS5) digestion resistance as measured by AOAC method 991.43. Cracker types were given solely as a test meal once a week over a period of 3 weeks. Glucose, insulin, and fermentation responses were evaluated. Specific objectives met: Short term human trial of RS 5 effects on human physiological responses including gut fermentation was accomplished. Significant results achieved, including major findings, developments, or conclusions (both positive and negative): Blood glucose area under the curve (AUC) was not different between HA and RS5; both produced lesser AUC responses than CS (p < 0.001). Reduced insulin AUC was found only in HA when compared to CS (p < 0.01). In vitro digestion of crackers evaluated by AOAC method 2002.02 showed no difference between RS5 and HA but by AOAC method 991.43, all 3 starches differed from each other, with RS5 having significantly greater digestion resistance than did HA than did CS. Postprandial glucose (PPG) response was similar between RS5 and HA, which corresponded to RS content as measured by AOAC method 2002.02. Only HA significantly suppressed blood insulin response compared with CS. Fermentation, assessed by breath hydrogen, was greater after ingestion of RS5 than after eating HA or CS (p < 0.05). Fermentation assessed by fecal short chain fatty acid (SCFA) contents over 2 days after starch feeding was not different between cracker types. Gastrointestinal bloating was significantly greater with RS5 than with HA or CS, but the symptom score was in the range of mild discomfort only. RS5 was shown to be a well-tolerated fermentable digestion-resistant starch that diminished blood glucose response in a test meal compared with conventional starch. Key outcomes or other accomplishments realized: This study showed that RS5 has promise as a fermentable digestion resistant starch that can be incorporated into palatable food products that could be used to enhance satiety based on previous studies of effects of fermentable resistant starches on satiety hormones such as polypeptide YY. RS5 may also be considered in the future to be useful to control blood glucose levels as needed for individuals such as those with type 2 diabetes. Objective 3: Major activities completed: Since our prior studies on the impacts of dietary resistant starch and antibiotics in the drinking water on colon pre-cancerous lesions in rats revealed that the mucin depleted foci lesions were observed in rats not treated with chemical carcinogen we decided to conduct experiments in mice on colon pre-neoplasia before beginning a study of colon cancer development. We initially did a validation study to select a dose of carcinogen and this study supported using a dosage of 7.5 mg azoxymethane (AOM)/kg body weight administered 4 times at weekly intervals to induce pre-neoplasia in the colon. Research was then conducted to examine impacts of diets containing 55% starch by dry weight of control starch (CS), High Amylose( HA7) octenyl succinic bound onto HA7 (OSA) and RSS on the development of AOM-induced aberrant crypt foci (ACF) (colon cancer precursors) in mouse colon. The CS and HA7 were used as the controls. After being injected with AOM or saline solution (control) while being fed the CS diet the rats were fed as described above for 10 weeks following the last AOM treatment. After the rats were sacrificed ACF numbers were counted in the distal colon. Specific objectives met: A study of the impact of control starch HA7, OSA, and RS5 on colon pre-cancerous ACF was accomplished. Significant results achieved, including major findings, developments, or conclusions (both positive and negative): The SAC diet, despite its high resistant content, produced the highest average ACF per mouse (~1.7) compared with the CS ( ~1.2); HA7 (~.5) and OSA (~1.3). Borderline statistical significance in ACF numbers was between the HA7 and SAC groups (P=0.9) with about a threefold yield of ACF in the RS5 group. There were no MDFs observed in the colons of the mice. Key outcomes or other accomplishments realized: Our most recent study in mice suggested that RS5 may actually increase the yield of colon pre-cancerous lesions. Because of this we are conducting a 36 week study with the CS, HA7 and RS5 diets at 55% of the rodent diet following AOM initiation to determine if our recent result is predictive of impacts on colon carcinogenesis.

Publications

  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Ai, Y., Nelson, B., Birt, D. F., and Jane, J. (2013) In vitro and in vivo hydrolysis of octenyl succinic starch. Carbohydrate Polymers. 98:1266-1271.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Moore, S., Ai, Y., Yangcheng, H., and Jane, J. (2013) In vitro and in vivo digestibility of resistant starch. Starch Update 2013: the 7th International Conference on Starch Technology. In Bangkok, Thailand. Oral presentation.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Haugabrooks E, Ai Y, Jane J-L, Hendrich S (2013) High Amylose and Stearic Acid-Modified Resistant Starch: Human Post-Prandial Gut Fermentation and Blood Glucose Response FASEB J April 9, 2013 27:125.8. Oral presentations given at Experimental Biology 2013, Boston, MA.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Cray NL, Pillatzki A, Zhao Y, Birt DF, Whitley EM. Effects of dietary resistant starch on beta-catenin in azoxymethane-treated colonic epithelium. Experimental Biology 2013, Boston, MA, April 20-24, 2013. Oral presentations given at Experimental Biology 2013, Boston, MA.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Birt, D.F. Diet, genes and microbes; complexities of colon cancer prevention at the Society for Toxicologic Pathology Annual Symposium in Portland, Oregon, on June 16-20, 2013. Oral presentation.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Ai, Y., Haugabrooks, E., Nelson, B., Hendrich, S., Birt D., and Jane J. Effects of lipids on physical properties, enzymatic hydrolysis, and nutritional benefits of starchy foods. Institute of Food Technologists Annual Meeting. Chicago Ill, July 13-16, 2013. Oral Presentation.
  • Type: Theses/Dissertations Status: Other Year Published: 2013 Citation: Haugabrooks E (2013) Evaluating the use of resistant starch as a beneficial dietary fiber and its effect on physiological response of glucose, insulin, and fermentation. Iowa State University Library, Ames, IA.


Progress 09/01/11 to 08/31/12

Outputs
OUTPUTS: In our previous studies, we found that high-amylose corn starch-stearic acid complex (Resistant Starch Type 5, RS5) had great resistance to in vivo starch hydrolysis and, thus, large quantities of starch and stearic acid were found in the rat feces. The great enzymatic resistance and hydrophobicity of the RS5 was hypothesized to cause its inhibitory effects on the azoxymethane (AOM)-induced preneoplastic lesions (colon cancer precursors) in the rat colon. To test this hypothesis, we prepared a hydrophobic octenyl succinic (OS) starch for the study. Research was conducted to investigate effects of octenyl succinic anhydride (OSA) modification (3% or 10%) of starch on the in vitro and in vivo enzymatic hydrolysis of normal corn (NCS) and high-amylose corn starch (HA7). Resistant starch (RS) contents of the native and modified starches after cooking were analyzed using the Englyst method. To prepare diets for rats, the NCS, HA7 and OS (10%)-HA7 were cooked and then mixed with other ingredients with 55% starch content. The rats were divided to three groups and fed with each of the diets for a total of nine weeks. Daily feces weights, feces starch and lipid contents, and body weights of the rats were analyzed each week. After the feeding period, the rats were sacrificed to examine their cecum tissue weights, cecal content weights and pH values. Results of this study were reported at the Institute of Food Technologists Annual Meeting & Food Expo, Las Vegas, NV, June, 2012, and at the American Association of Cereal Chemists International Annual Meeting, Hollywood, FL, October, 2012. Breads were prepared with 20%-50% RS5, with or without adding a dough modifier, to increase RS contents of the breads with a good eating quality. The results were presented at the Corn Utilization and Technology Conference, Indianapolis, IN, June, 2012. Research was also conducted to examine impacts of OS (10%)-HA7 and RS5 on the development of AOM-induced aberrant crypt foci (ACF) and mucin depleted foci (MDF) (colon cancer precursors) in rat colon. The NCS and HA7 were used as the control. After being injected with AOM or saline solution (control), the rats were fed as described above. After the rats were sacrificed, ACF and MDF numbers were determined in the distal colon. Results of this study were presented at the 11th Annual American Association for Cancer Research International Conference on Frontiers in Cancer Prevention Research, Anaheim, CA, October, 2012. Impacts of the RS5 on postprandial blood glucose response were analyzed and compared with the NCS and HA7 in a human study. The starches were used to prepare crackers with 75% starch content. RS contents of the crackers were analyzed using the AOAC Method 991.43 and AOAC Method 2002.02. After 10-h fast, human subjects ingested the test cracker containing 50 g starch. Plasma-glucose concentrations of the subjects were determined at different time intervals after the ingestion of the cracker. Breath hydrogen of the human subjects was measured to evaluate fermentation of different starches. PARTICIPANTS: Individuals: Jay-lin Jane, Ph.D., Principal Investigator; Diane Birt, Ph.D., Co-Investigator; Suzanne Hendrich, Ph.D., Co-Investigator; Tong Wang, Ph.D., Collaborator; Yongfeng Ai, Ph.D. student and Graduate Assistant; Bridget Nelson, M.S. student and Graduate Assistant; Esther Haugabrooks, Ph.D. student and Graduate Assistant. TARGET AUDIENCES: As the results of this study showed, nutritionists can now recommend resistant starch for diabetics and prediabetics to maintain a steady blood glucose level. Resistant starch can also be consumed to prevent colon cancer. Other audiences are the food industry, consumers who are interested in intervention of Type-2 diabetes, overweight and colon cancer, grain processors, and the feed industry. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The RS content of the cooked NCS increased after modification with OSA. The RS content of the cooked HA7, however, decreased slightly after OSA modification because of the lower gelatinization temperature of the modified starch. After mixing with other ingredients to prepare diets, the NCS, HA7 and OS (10%)-HA7-diet had 1.5%, 10.9% and 12.4% RS, respectively. After ingesting the diets, rats fed with the OS (10%)-HA7-diet had substantially greater cecal content weights and feces weights (~4X of the NCS control, dry-weight basis). The feces from the rats fed with the OS (10%)-HA7-diet showed significantly larger starch-contents (equivalent to 18.8%-28.9% starch not being utilized) than that with the HA7 (1.7%-4.8% not utilized) and NCS (0.1% not utilized). These results showed that the OS (10%)-HA7 was substantially more resistant to in vivo starch hydrolysis and, thus, was discharged in the feces in much larger quantities. The in vivo resistance of OS (10%)-HA7 could be resulted from physical interactions between the hydrophobic starch and the hydrophobic components (e.g., lipids and proteins) in the diet as well as the surface of the intestine. The feces from the OS (10%)-HA7-fed rats also showed much larger lipid contents than that from the other two groups. The reduced in vivo digestibility of the starches, however, did not significantly affect the body-weight gain of the rats. This unusual starch digestive pattern of the OS (10%)-HA7 was very intriguing. Further studies are conducted to reveal the mechanism of the reaction. For the breads made with varied levels of RS5, sensory studies conducted with 100 panelists showed no significant differences between the bread made with 20% RS5 and the control bread in overall opinion, likeliness of purchase, and ranking. These sensory study results indicate that the RS5 can be used to make bread with similar taste to white bread. This RS5-bread can be served in meals for diabetic patients to control the blood glucose and for other people to prevent developments of diabetes. Analyses of the MDF number in the distal colon of AOM-treated rats showed that the rats fed with the RS5-diet had a small number of MDF (0/rat), OS (10%)-HA7-diet (0.2/rat), NCS diet (0.4/rat), and HA7 diet (0.5/rat). The saline-treated rats showed very small number of MDF (0.2/rat or less) for different diets. These results suggested that adding the RS5 and OS-HA7 into diets could reduce the development of AOM-induced colon cancer precursors. Crackers prepared with the NCS, HA7 and RS5 had RS contents of 6%, 24% and 58%, respectively, analyzed using the AOAC Method 991.43, and 0.3%, 17.5% and 16.0%, respectively, analyzed using the AOAC Method 2002.02. Compared with the NCS-cracker, ingestion of the crackers prepared with the HA7 and RS5 resulted in significantly lower postprandial blood glucose responses in human subjects, but no significant differences were found between the HA7 and RS5. In vivo glucose responses correlated better with the RS contents analyzed using the AOAC Method 2002.02. Results of breath hydrogen of the human subjects showed that more RS fermentation was observed in the RS5 group.

Publications

  • Ai, Y., Hasjim, J., and Jane, J. (2013) Effects of lipids on enzymatic hydrolysis and physical properties of starch. Carbohydrate Polymers. 92, 120-127.


Progress 09/01/10 to 08/31/11

Outputs
OUTPUTS: Research was conducted to investigate effects of the structure of starch, the presence and structures of lipids, and cooking methods on the enzymatic-hydrolysis rate of starch using porcine pancreatic alpha-amylase (PPA). Starch-hydrolytic rates of water-boiled ground normal and high-oil corn kernels were analyzed, and results were compared to reveal the impact of oil contents. Starch-hydrolytic rates of boiled, ground normal and waxy (glutinous) corn kernels and japonica, indica, and waxy rice grains were examined to compare the impacts of starch structures. The japonica, indica, and waxy rice were cooked using different methods to prepare steamed rice, fried rice and rice pilaf. Starch hydrolytic-rates of the steamed rice, fried rice and rice pilaf were analyzed to reveal impacts of cooking methods. Results of these studies were reported at the Institute of Food Technologists Annual Meeting & Food Expo, New Orleans, LA, June, 2011, and at the Starch Update International Conference on Starch Technology, Bangkok, Thailand, November, 2011. Research was conducted to investigate effects of different heat treatments and storage conditions on the physicochemical properties of starch in two oat varieties (Dancer and Rockford). After being steamed (95 degree C), dry roasted (106 degree C), or without heat treatment, the oat kernels were dehulled and then stored at room temperature (~23 degree C) and 85% relative humidity. Kernels in the hull without heat treatments were used as the control. Starch hydrolytic-rates, thermal properties, and pasting properties of the isolated starch and ground kernels were analyzed after storage. The results were reported at American Association of Cereal Chemists International Annual Meeting, Palm Springs, CA, October, 2011. Impacts of octenyl succinic anhydride (OSA) modification on structures, physical properties, and resistant starch contents of normal and high-amylose corn starch were examined. The starch varieties were modified with 3% or 10% (w/w, dry starch basis) OSA at pH 8.0 and 35 degree C. Degrees of substitution, resistant starch contents, thermal properties, and pasting properties of the control and modified starches were analyzed, and the results were compared to understand the effect of hydrophobic derivatives on starch properties. PARTICIPANTS: Individuals: Jay-lin Jane, Ph.D., Principal Investigator; Diane Birt, Ph.D., Co-Investigator; Suzanne Hendrich, Ph.D., Co-Investigator; Tong Wang, Ph.D., Collaborator; Elizabeth Whitley, Ph.D., Collaborator. Yongfeng Ai, Ph.D. student and Graduate Assistant; Yinsheng Zhao, Ph.D. student and Graduate Assistant; Joshua Leutscher, MS student and Graduate Assistant; Michael Reed, MS student and Graduate Assistant; Donghai Wang, Ph. D., Professor, Kansas State University. TARGET AUDIENCES: Nutritionists, the food industry, consumers who are interested in intervention of Type-2 diabetes, overweight and colon cancer, grain processors, and the feed industry. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Comparison studies between normal (4.3% lipid content) and high-oil corn (5.5% lipid) showed that starch of the ground high-oil corn kernels after boiling was hydrolyzed more slowly than that of the normal corn counterpart using PPA. These results were consistent with our earlier studies showing that adding lipids to cooked starch reduced the rate of enzyme conversion of starch to glucose. The slow release of glucose from starch after ingesting starchy food (known as a low glycemic index) can provide health benefits, including intervention of insulin resistance and diabetes. Impacts of starch structures, such as the amylose content, on glucose releasing rate showed that both waxy (glutinous) corn and rice, which consisted of no amylose, displayed substantially faster rates of starch hydrolysis to release glucose than the normal corn and rice varieties, which consisted of 20-30% amylose. The results suggested that the ingestion of glutinous starchy foods would result in a spike of blood glucose, which could induce insulin resistance and diabetes. Effects of cooking methods, including steamed, fried, and pilaf of rice, on starch hydrolytic-rates showed that the fried rice displayed the slowest starch hydrolysis, whereas the steamed rice displayed the fastest starch hydrolysis. The slowest starch-hydrolysis of the fried rice could be attributed to the starch-lipid interaction as well as starch retrogradation after an overnight storage of the rice in a refrigerator. The results showed that proper processing of starchy foods can reduce the glycemic index for intervention of diabetes. Starch isolated from the steam-treated oat kernels showed smaller gelatinization enthalpy-changes than the control, indicating partial gelatinization of starch caused by steaming. Compared with the control, the peak viscosities of the ground oat samples increased after steam treatment. This could result from the hydration of beta-glucan during the steam treatment. After 2-month storage, however, the peak viscosity decreased for the samples, suggesting retrogradation or amylose-lipid complex formation during storage. The percentage starch-hydrolysis of raw steam-treated ground oat kernels after 24-hour incubation with PPA was lower than the control. The difference could be the result of the viscosity increase caused by the hydration of beta-glucan during steaming. After modification with 3% or 10% octenyl succinic anhydride (OSA), the resistant starch content of the boiled normal corn starch increased from 1.7% to 6.0% and 15.6% (Englyst method), respectively, but that of the high-amylose corn starch decreased from 24.8% to 23.7% and 20.9%, respectively. The decrease in the resistant starch content of the high-amylose corn starch after OSA modification could be attributed to that the OS derivatization reaction dissociated amylose double helices. The OSA-modified high-amylose corn starch is currently being used for an animal feeding study to understand the effect of the hydrophobic moiety of the starch on colon health.

Publications

  • Ai, Y. Reed, M. Yangcheng, H. Leutscher, J. Jiang, H. and Jane, J. (2011). Effects of varieties and cooking methods of corn and rice on starch hydrolytic rate. Starch Update 2011: the 6th International Conference on Starch Technology. In Bangkok, Thailand.
  • Ai, Y. Medic, J. Jiang, H. Wang, D. and Jane, J. (2011) Starch characterization and ethanol production of sorghum. Journal of Agricultural and Food Chemistry. 59, 7385-7392.
  • Zhao, Y. Hasjim, J. Li, L. Jane, J. Hendrich, S. and Birt, D. F. (2011). Inhibition of azoxymethane-induced preneoplastic lesions in the rat colon by a cooked stearic acid complexed high-amylose cornstarch. Journal of Agricultural and Food Chemistry. 59, 9700-9708.


Progress 09/01/09 to 08/31/10

Outputs
OUTPUTS: Research was conducted to investigate impacts of different lipids on hydrolysis rates and physicochemical properties of selected starches and understand the mechanism. Four different starch samples were selected for this study: normal corn, tapioca, waxy corn, and high-amylose corn starch. Corn oil, soy lecithin, palmitic acid, oleic acid, and linoleic acid were used representing triglycerides, phospholipids, and free fatty acids of different degrees of unsaturation. Enzymatic hydrolysis, thermal property, and pasting property of the starch were analyzed. 13C- nuclear magnetic resonance was used to reveal the interactions between starch molecules and the lipids. Results of the studies were presented at the Corn Utilization and Technology Conference in Atlanta, GA, June, 2010 and at the Institute of Food Technologists Annual Meeting & Food Expo in Chicago, IL, July 2010. Research was conducted to examine in vivo digestibility of high-amylose corn starch-stearic acid complex using a rat model. Normal corn starch diet, high-amylose corn starch diet, and high-amylose corn starch-stearic acid complex diet were prepared and fed to different rat groups. Resistant starch content of each diet was analyzed. The rat feces was collected, weighed, and analyzed for the total starch and lipid contents, starch morphology, and free fatty acid compositions. Results of the studies were presented at the Institute of Food Technologists Annual Meeting & Food Expo in Chicago, IL, July 2010. Effects of drying conditions and temperature of corn kernels on enzymatic hydrolysis of starch and physical chemical properties of the corn after storage were studied. Results of the studies have been published as a research paper. The kernel composition, starch structure, and starch hydrolytic rate of different sorghum varieties were studied and compared with that of corn kernels. Results from this study helped us understand how sorghum kernel composition and starch structure determine the enzymatic hydrolysis of starch in dry-grind sorghum. A manuscript reporting the results obtained from this study will be submitted to a scientific journal. PARTICIPANTS: Individuals: Jay-lin Jane, Ph.D., Principal Investigator; Diane Birt, Ph.D., Co-Investigator; Suzanne Hendrich, Ph.D., Co-Investigator; Tong Wang, Ph.D., Collaborator; Elizabeth Whitley, Ph.D., Collaborator. Yongfeng Ai, Ph.D. student and Graduate Assistant; Stephan Setiawan, MS student and Graduate Assistant; Yinsheng Zhao, Ph.D. student and Graduate Assistant; Joshua Leutscher, MS student and Graduate Assistant; Donghai Wang, Professor, Kansas State University, and Nugenplasm. TARGET AUDIENCES: Nutritionists, the food industry, consumers who are interested in intervention of Type-2 diabetes, overweight, and colon cancer, grain processors, and the feed industry. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
A cooked normal corn starch sample showed 72.0% hydrolysis after 2 hour incubation with porcine pancreatic alpha-amylase. With the presence of oleic acid (10%), the hydrolysis of the starch decreased to 61.1%, followed by corn oil (61.4%), palmitic acid (61.8%), soy lecithin (63.5%), and linoleic acid (66.9%). The percentage hydrolysis of cooked tapioca and high-amylose corn starch followed similar trends with the presence of various lipids. The percentage hydrolysis of waxy corn starch, however, was not significantly affected by the presence of those lipids. Studies on the thermal property of starch showed that normal corn starch decreased retrogradation rate but tapioca and waxy corn starch increased with the presence of lipids. DSC thermograms of normal corn and tapioca starch showed a melting thermal transition of the amylose-fatty acid complex with the presence of fatty acids. The pasting temperature of normal corn starch cooked alone was 79.8 degree C; it decreased by 2.0 degrees and 10.2 degrees with the presence of 10% corn oil and soy lecithin, respectively. The final viscosity of corn starch paste increased substantially with the presence of palmitic acid and linoleic acid. 13C-NMR spectra of amylodextrin aqueous solutions showed that the chemical shifts of Carbon 1 and 4 moved downfield with the presence of oleic acid, corn oil and soy lecithin, indicating that corn oil and soy lecithin also formed helical complex with starch molecules. The results were consistent with the decrease in enzymatic hydrolysis of starch in the presence of those lipids. In vitro analysis results showed that the resistant starch contents of a normal corn starch diet (NCSD), a high-amylose corn starch diet (HACSD), and a high-amylose corn starch-stearic acid complex diet (HASACD) were 2.5%, 12.5%, and 30.1%. The daily feces discharged by rats fed with those diets were 0.20g, 0.45g, and 1.65g (dry weight), respectively. The starch contents of the feces were 0.0%, 16.8%, and 44.0%, and the lipid contents were 16.8%, 11.7%, and 22.0%, respectively. Starch isolated from the feces of rats fed with HACSD and HASACD displayed crystalline structures viewed under a polarized light microscope. A substantial amount of free stearic acid was found in the feces of rats fed with HASACD. The results indicated that the high-amylose corn starch-stearic acid complex was highly resistant to enzymatic hydrolysis both in vivo and in vitro, and was discharged in feces. Sun-dried (35 degree C) and machine-dried (80 degree C) corn kernels showed different digestibility and functional properties after storage. Studies showed that endogenous enzyme activities of the corn remained after sun drying and caused severe degradation of starch molecules and reduction in the viscosity after storage. Sorghum starch had a slightly slower starch hydrolytic rate than corn starch. The differences could be attributed to fewer short branch-chains of the sorghum amylopectin. The dry-grind sorghum displayed a significantly slower starch hydrolytic rate than the dry-grind B73 corn. The difference could be resulted from the presence of tannin and more compact protein matrices in dry-grind sorghum.

Publications

  • Ai, Y., Setiawan, S., and Jane, J. (2010) Impact of lipids on digestive rate and physicochemical properties of starches. Institute of Food Technologists Annual Meeting & Food Expo. Chicago, IL.
  • Setiawan, S., Widjaja, H., Rakphongphairoj, V., and Jane, J. (2010) Changes in starch structures and functions after storage of dried con-kernels at an elevated humidity. Journal of Agricultural and Food Chemistry, Published online.
  • Ai, Y. and Jane, J. (2010) Effect of different lipids on enzyme digestibility and properties of corn starches. Corn Utilization and Technology Conference. In Atlanta, GA.