Progress 10/01/04 to 09/30/10
Outputs
OUTPUTS: Infrared radiation may be used to simulate an immersion frying heat flux and create products with fried-like textures but lower fat contents. The objective of this study was to determine the process parameters needed to produce partially-fried, infrared-finished donuts comparable to fully-fried (control) donuts. Eight different sets of infrared oven parameters were tested. Instrumental analysis showed that all infrared-finished donuts had significantly (p less than or equal to 0.05) lower fat content (25.6%-30.6%) than the control (33.7%). Setting the emitters in a height gradient from 70 mm to 50 mm or at a constant height of 60 mm above the belt in the infrared oven produced donuts that were most instrumentally similar to the control. Infrared-finished donuts had comparable (p less than or equal to 0.05) overall acceptance scores to the control, 5.28-5.85 and 5.83, respectively. Infrared radiation may be used to finish-fry partially-fried donuts, yielding a product similar to a fully-fried donut but with significantly lower fat content. Conferences: Melito, H. and Farkas, B.E. 2009. Process parameters for producing partially fried, infrared-finished donuts, Abstract. National IFT Annual Meeting, Anaheim, CA, USA June 6- June 9. Melito, H. and Farkas, B.E. 2009. Physical properties of gluten-free donuts, Abstract. National IFT Annual Meeting, Anaheim, CA, USA June 6- June 9. Melito, H. and Farkas, B.E. 2009. Process parameters for producing gluten-free, partially-fried, infrared-finished donuts, Abstract. National IFT Annual Meeting, Anaheim, CA, USA June 6- June 9. Yaniv, Y.R., Farkas, B.E., Keener, K.M. 2007. Mathematical modeling of high intensity infrared heating of a food matrix. Paper 141-11, Abstract. National IFT Annual Meeting, Chicago, IL, USA, July 28-August 1. PARTICIPANTS: Farkas, B.E.: Principle Investigator. Melito, H.S.: Masters student, completed 2009 Yaniv, Y.R.: Masters student, completed 2007 TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Fried foods are enjoyed worldwide as snacks or part of a meal. However, because these foods are deep-fried in oil, they tend to have a high fat content. It was hypothesized that this par-frying, Infrared(IR)-finishing process would be able to produce donuts with a lower fat content but instrumentally and sensorially comparable to fully-fried donuts. Statistical analysis (alpha=0.05) showed that all of the wheat par-fried, IR-finished donuts (25.6%-30.6%), most of the GF fully-fried donuts (26.3%-32.2%), and all of the GF par-fried, IR-finished donuts (23.7%-28.2%) had a significantly lower fat content than the wheat control (33.7%). Setting the emitters in either a height gradient from 45 mm to 25 mm or at a height of 35 mm above the top of the donut and using either IR time produced wheat par-fried, IR-finished donuts that were most instrumentally similar to the control, while using the same emitter settings and an IR-finishing time of 39 s produced GF par-fried, IR-finished donuts that were the most instrumentally similar to the control. Gluten-free fully-fried donuts made with a higher ratio of commercial GF flour to rice flour were more instrumentally similar to the control than donuts made with an equal ratio of commercial GF flour to rice flour, regardless of hydrocolloid used. Sensory scores of the wheat par-fried, IR-finished donuts (overall acceptance of 5.28-5.85) showed no significant differences from the control (5.83) with the exception of one slightly lower appearance score (5.69 for the par-fried, IR-finished donut versus 6.57 for the control). All GF fully-fried donuts (overall acceptance of 4.33-4.68) and all GF par-fried, IR-finished donuts (overall acceptance of 3.81-4.44) received significantly lower sensory scores than the wheat control (6.37 and 6.94, respectively). These results indicated that the GF donuts were not as well liked as the control, possibly due to their dryness. Overall, the par-frying, IR-finishing process was shown to significantly lower the fat content of both wheat and GF donuts while producing donuts instrumentally and sensorially comparable to fully-fried donuts made with the same formulation. This process may be used instead of a full-frying process to produce donuts instrumentally and sensorially similar to fully-fried donuts, but with a significantly lower fat content.
Publications
- Melito, H.S and Farkas, B.E. Submitted. Physical Properties of Gluten-Free Donuts. Journal of Food Quality (Pending). Melito, H.S and Farkas, B.E. 2011. Effect of infrared finishing process parameters on physical, mechanical, and sensorial properties of par-fried, infrared-finished gluten-free donuts. Journal of Food Engineering (Pending). Melito, H.S. and Farkas, B.E. 2012. Impact of Infrared Finishing on the Mechanical and Sensorial Properties of Wheat Donuts. Journal of Food Science. Vol. 77, No. 9, pp E224.
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: Food allergies and intolerances are a health concern both in America and worldwide. Gluten intolerance, affecting about 1% of the American population, is an inability to break down wheat gluten proteins, as well as similar proteins found in rye, barley and possibly oats. Consuming these proteins results in the gradual deterioration of the intestinal villi, causing malabsorption of nutrients and other health problems. Wheat allergy also indicates sensitivity to wheat proteins. When a person with a wheat allergy consumes wheat, there is an IgE-mediated response, stimulating a histamine release and causing a variety of symptoms such as nausea, GI distress, hives, and anaphylaxis. Treatment for both gluten intolerance and wheat allergy is a lifelong avoidance of wheat and wheat-containing products such as commercial soups and sauces. The need to avoid wheat and gluten-containing products has resulted in a demand for commercial wheat- and gluten-free (GF) products. Currently, there are some GF analogs to commonly consumed products, such as bread, cereals, and cookies; however, the texture and taste of these products differs from wheat products and the acceptability is widely variable. Fried foods are enjoyed worldwide due to their palatable texture and taste. However, many fried foods are either breaded or are made from dough containing wheat flour and must be avoided by people with wheat allergy or gluten intolerance. Considerable research has been done on formulating and improving GF breads, but few studies have examined GF fried products. As the percentage of Americans classified as overweight or obese increases, consumers are becoming increasingly health conscious. This has caused an increased demand for lower-fat alternatives to commonly consumed high-fat fried foods. Hydrocolloids and GF flours have already been shown to lower the fat content of fried foods. Using GF flours and hydrocolloids as a replacement for wheat flour in a fried product such as donuts allows people with wheat and gluten sensitivities to enjoy a common food. It may also provide a product with a significantly lower fat content than a similar product made with wheat flour. The objective of this study was to quantify the effects of different hydrocolloids mixed with different GF flours on the physical properties and sensory aspects of GF donuts, as measured by instrumental and sensorial analysis, and to determine which formulation is most comparable to wheat donuts. PARTICIPANTS: Farkas, B.E.: Principle investigator, directed research and graduate student on project. Melito, H.S.: Graduate student, Developed research TARGET AUDIENCES: Persons interested in the development of gluten-free fried foods. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Statistical analysis (alpha=0.05) showed that most GF donuts had significantly lower fat content (26.3%-32.2%) than the wheat control (33.7%). Donuts made with a 3:1 ratio of commercial GF flour to rice flour were more instrumentally similar to the wheat control than donuts made with a 1:1 ratio of commercial GF flour to rice flour. A higher ratio of commercial GF flour to rice flour was correlated to increased fat content. All GF donuts received significantly lower overall acceptance scores (4.33-4.68) than the wheat control (6.37). Although GF donuts were not as sensorially acceptable as wheat donuts, they were instrumentally similar to and had a lower fat content than the wheat control.
Publications
- No publications reported this period
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: The ability to predict changes in the physical characteristics of a food material during its processing is vital in the continued improvement in safety, quality, and efficient food processing operations. This station project addresses two areas of food processing involving phase change and/or a moving boundary: 1) melting/solidification and condensation/vaporization of water (freezing, drying, immersion frying), and 2) denaturation of protein and gelation of starch induced by thermal and non-thermal processing for preservation. Human milk is a superior source of nutrition because it provides many health benefits to the neonate, including reduction of the risk of infection from microbial pathogens. Neonates acquire some immunological assistance from the mother during pregnancy, but it is during breastfeeding that the infant gains extra protection from antibodies and antimicrobial proteins such as immunoglobulin A (IgA) and lysozyme, as well as immune cells. Although animal milk or infant formulas can be used as nutritional alternatives to breast milk, they do not supply the neonate with the same kinds and/or levels of key antimicrobial components that are present in human milk. Low Temperature Long Time (LTLT) pasteurization assures the safety of banked human milk; however, heat can destroy important nutritional biomolecules. High pressure processing (HPP) shows promise as an alternative for pasteurization of breast milk. The purpose of this study was to investigate the efficacy of HPP for inactivation of selected bacterial pathogens in human milk. Human milk was inoculated with one of five pathogens (1x10^8-1x10^9 CFU/ml), while 0.1% peptone solution solutions with the same levels of each organism were used as controls. The samples were subjected to 400 MPa at 21 to 31C for 0 to 50 min or to 62.5C for 0 to 30 min (capillary tube method) to simulate LTLT pasteurization. Tryptic soy agar and selective media were used for enumeration. PARTICIPANTS: Farkas, B.E.: Principle investigator, developed hypothesis for high pressure of human milk, directed research and graduate student on project. Jaykus, L.A.: Advised on microbiological methods. Viazis, S.: Graduate student, Developed research plan in conjunction with the PI, conducted laboratory research, wrote preliminary drafts of publications. TARGET AUDIENCES: Human milk banks and those that work in and with the milk banks. Researchers studying human milk processing safety and quality. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Traditional thermal pasteurization resulted in inactivation (>7 logs) of all pathogens within 10 min. In human milk and in peptone solution, a 6 logs reduction was achieved after 30 min of HPP for Staphylococcus aureus ATCC 6538. After 30 min, S. aureus ATCC 25923 was reduced by 8 logs and 6 logs in human milk and peptone solution, respectively. Treatments of 4 min and 7 min resulted in an 8 logs inactivation of Streptococcus agalactiae ATCC 12927 in human milk and peptone solution, respectively, while Listeria monocytogenes ATCC 19115 required 2 min for an 8 logs inactivation in human milk. Escherichia coli ATCC 25922 was inactivated by 8 logs after 10 min in peptone solution and by 6 logs after 30 min in human milk.This research suggests that high pressure processing may be a promising alternative to thermal processing for pasteurization of human milk.
Publications
- Viazis, S., Farkas, B.E., Jaykus, L.A. 2008. Inactivation of Bacterial Pathogens in Human Milk by High-Pressure Processing. Journal of Food Protection, 71 (1): 109-118.
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Progress 10/01/06 to 09/30/07
Outputs
The ability to predict changes in the physical characteristics of a food material during its processing is vital in the continued improvement in safety, quality, and efficient food processing operations. This station project addresses two areas of food processing involving phase change and/or a moving boundary: 1) melting/solidification and condensation/vaporization of water (freezing, drying, immersion frying), and 2) denaturation of protein and gelation of starch induced by thermal and non-thermal processing for preservation. Over the past year high pressure processing was studied as an alternative to low temperature long time pasteurization of human milk. Banked human milk is processed using Low Temperature Long Time (LTLT) pasteurization, also known as Holder pasteurization. This treatment inactivates pathogenic microorganisms, but degrades important biochemical components. The kinetics of high pressure processing (HPP) favor the reduction of pathogens with
retention of biochemical activity and nutritional quality of foods. The objective of this study was to investigate the effects of HPP on total Immunoglobulin A (IgA) and lysozyme activity in human milk. Human milk was subjected to 400 MPa for 30 to 120 minutes or heat-treated at 62.5 C for 30 minutes. Before and after processing, an indirect modified Enzyme Linked Immunosorbent Assay (ELISA) and a Micrococcus lysodeikticus turbidimetric assay were performed to measure IgA immunoactivity and lysozyme activity, respectively. Pressure-treated samples retained significantly higher (p<0.05) levels of IgA and lysozyme activity compared to LTLT-treated samples. These data suggest that HPP is a potential alternative to thermal pasteurization of human milk that can give greater retention of some bioactive components. Further research should be done to determine whether HPP has the ability to inactivate potential pathogens of concern for donor human milk in human milk banks. Research on an
important North Carolina crop, sweet potatoes, was conducted to develop a mathematical simulation of storage facilities. Year-round supply of quality sweetpotatoes requires they be stored in a controlled environment where the relative humidity is 85% and the potato temperature is maintained at 14 C. Design and construction of storage facilities involves many trade-offs between physical, operational, and economic parameters. The complex interaction between these parameters can result in an expensive trial and error building design process. The objective of this research was to develop a numerical simulation of a sweetpotato curing and storage facility. A Matlab/Simulink based simulation was developed that allows the user to evaluate design trade-offs. Inputs to the simulation include product mass and respiration characteristics, building design parameters, and weather data. Outputs of the simulation include electrical cost for product cool-down and long-term storage, equipment cycle
times, product temperature, and room psychrometrics. This simulation environment allows the user to evaluate storage unit design and modifications prior to incurring the implementation expense.
Impacts
Results from research conducted this year will be used to improve the safety and quality of the foods studied.
Publications
- Viazis, S., Farkas, B.E., and Allen, J.C. (2007) Effects of High Pressure Processing on Immunoglobulin A and Lysozyme Activity in Human Milk. Journal of Human Lactation. 23(3), 253-261.
- Reinitz, H.W., Farkas, B.E., Boyette, M.D. (2007) Simulation Environment for the Analysis of Sweetpotato Curing and Storage Facilities. ASABE Program and Abstract Book Annual Meeting, Minneapolis, MN, USA (Session 109-2, Paper No. 074022).
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Progress 10/01/05 to 09/30/06
Outputs
Infrared heating has been used by the food industry for many years. Some of the advantages of infrared heating are its high intensity, ability to penetrate the product, and precise control. While infrared heating has unique advantages over convective and conductive heating, the complex mathematics and lack of optical property data associated with the radiant process have hindered extensive numerical simulation for process design and optimization. The objective of this research was to develop a mathematical model to predict temperature change and crust formation during high intensity infrared heating of a food matrix. A series of equations for unsteady state heat transfer, internal heat generation, and a moving boundary demarked by a phase change interface were developed. Beer's law was assumed to describe subsurface radiant energy absorption. The equations were solved numerically using explicit finite differences and commercially available software. Russet potato was
used in a series of radiant heating experiments designed to test the output of the mathematical model. Surface and center temperatures and crust thickness were measured for a range of radiant flux intensities, and the data compared to the simulation output. Simulated surface temperatures agreed well with measured surface temperature during the initial 150 s of heating. Towards the end of the heating time, higher incident radiant flux (26,900 and 22,500 W/m2) resulted in higher simulated surface temperature than laboratory data. A lower flux setting (17,500 W/m2) resulted in lower simulated temperatures than measured. The model was able to predict center temperature for the first 150 s of heating for the higher flux settings, followed by higher measured temperature for 26,900 W/m2 incident flux. Measured center temperature for the lowest flux setting was lower than simulated temperatures throughout the duration of heating. Experimental crust thickness determination was based on sample
mass loss. The model did not account for evaporation of moisture at temperatures less than 100C, resulting in lower crust thickness predictions for initial stages of heating. It was hypothesized that variable optical and thermal properties of the matrix, as well as moisture diffusion, and internal pressure build up, were possible causes for deviation of predicted temperatures and crust thickness from laboratory data.
Impacts
The use of high intensity, controlled flux infrared heating as an alternative to immersion frying has potential to produce fried-like products with greatly reduced oil and caloric content.
Publications
- No publications reported this period
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Progress 10/01/04 to 09/30/05
Outputs
Heat transfer rates during frying were studied at three oil quality levels (new, midgrade and abused). Heat flux, convective heat transfer coefficient and oil viscosity were measured at three temperatures (120, 150, and 180 C) and at each oil quality level. Interfacial tension at an oil/water interface was determined at room temperature at each oil quality level. An increase in convective heat transfer coefficient and heat flux was found as oil was degraded from the new to midgrade level. Further degradation of the oil from midgrade to the abused level led to a decrease in heat flux and convective heat transfer coefficient from the midgrade level. It was hypothesized that heat transfer rates were enhanced at the midgrade level by a decrease in interfacial tension with little change in oil viscosity. Heat transfer was then suppressed by the increased viscosity of the abused oil while little change in interfacial tension was found.
Impacts
Mechanistic study of immersion frying heat transfer has resulted in the development of a new process for production of reduced fat content fried like foods. We expect continued development of this process through pilot scale process engineering and the use of mathematical modeling.
Publications
- No publications reported this period
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Progress 10/01/03 to 09/30/04
Outputs
New project. No report.
Impacts
None yet.
Publications
- No publications reported this period
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