Progress 02/01/01 to 01/31/06
Outputs
The overall objective of this project was to develop tailored functional ingredients of predictable performance by using enzymes as process aids and by understanding the contribution of molecular structure to function of ingredients. Through the combined use of biochemical, physical, and rheological techniques, a good understanding of the structure-function relationship of pectin-protein interactions was developed. Crude extracts of pectinmethylesterase (PME) and PME isozymes were used to modify pectins in situ and in vitro. PME was extracted from citrus and used to increase firmness of strawberries that could be used in frozen dairy desserts and fermented dairy foods. In addition a method to identify the translocation and distance of penetration of the enzyme was developed. This procedure was unique in terms of rapid assessment and the avoidance of use of fluorescent tags and sophisticated microscopes. From this method, it was shown that highly de-esterified pectins
are created well within the internal structures of strawberries, which are likely responsible for the enhanced firmness. When applied to eggplant, vacuum infusion of PME increased the response to antibodies that are specific for de-esterified pectin. In another objective of this project, changes in PME and other cloud proteins induced by cations and pectin interactions was studied. It was proposed that the PME and PME fragments that were present in juices that rapidly clarified resulted from the unique charge distribution in modified pectins. The presence or absence of PME fragments was related to raw material source, chromatography conditions and possibly a protease. Some of the parameters that moderate cloud, cloud composition, cloud stability of juices, juice blends, and juice added beverages were denoted. These include characterization using rheological methods, composition of neutral sugars and process conditions. After controlled modification of pectins and characterization of
the interaction with proteins under well defined conditions, the production and process parameters that influence stability of foods and beverages was determined. Predictive models for successful performance in food systems was developed. The results of the proposed project contribute to our understanding of the mechanism of colloidal stability of polysaccharide-protein dispersions, the influence of processing technology on physical stability and enhance the development of food processing methods to improve quality, stability, convenience and value of foods.
Impacts
Natural constituents of plants, like pectins, can be changed with naturally occuring enzymes. These modified pectins prevent mushiness of processed vegetables and water leakage from frozen vegetables. Modified pectins may be used to keep the quality of convenient, stable and healthier foods.
Publications
- Beaulieu, M., Corredig, M., Turgeon S.L., Wicker, L., Doublier, J.L. 2005. The formation of heat-induced protein aggregates in whey protein/pectin mixtures studies by size exclusion chromatography coupled with multi-angle laser light scattering detection. Food Hydrocolloids 19(5): 803-812
- Banjongsinsiri, P., Shields, J. and Wicker, L. 2004/5. Vacuum Infusion of Plant or Fungal Pectinmethylesterase and Calcium Affects Texture and Structure of Eggplant. J. Agric. Food Chem. 52: 8214-8223.
- Hunter, J., Wicker, L. 2005. De-Esterification of Pectin by Alkali, Plant and Fungal Pectinmethylesterases and Effect on Molecular Weight. J. Sci. Food Agric. 85 (13): 2243-2248.
- Kim, Y., Wicker, L. 2005. Soybean Cultivars Impact Quality and Function of Soymilk and Tofu. J. Sci. Food Agric. 85: 2514-1518.
- Koffi, E., Shewfelt, R., Wicker, L. 2005. Storage stability and sensory analysis of UHT processed whey-banana beverages. J. Food Quality 28: 386-401.
- Kim, Y., Teng, Q., Wicker, L. 2005. Action pattern of Valencia orange PME de-esterification of high methoxyl pectin and characterization of modified pectins. Carbohy. Res. 340:2620-2629.
- Kuchel, L., Brody, A.L., Wicker, L. 2005/6. Oxygen and its Reactions in Beer. Packaging Technology and Science. Accepted June, 2005
- Garti, N., Wicker, L. 2005. Pectinmethylesterase modified pectin interaction with whey protein isolate and stability of double emulsions, abstracts: 229th National Meeting of the American-Chemical-Society, San Diego, CA, USA; March 13 -17, 2005
- Samuel, D., Wicker, L. 2005. 99B-22 Effect on surface hydrophobicity of beta-lactoglobulin and interaction with unmodified and charge modified pectins. IFT Annual Meeting and Expo., New Orleans, July, 17-20, 2005
- Wicker, L. Keynote speaker. 2005. Invited address to International Congress: Functional Foods for Health, October 25-26, 2005, Medellin, Colombia
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Progress 01/01/04 to 12/31/04
Outputs
Enzymes as process aids. Technology was developed and optimized to infuse and to visualize infusion of external enzymes into fruit and vegetable tissue. A print technique was adapted to quantify the diffusion of PME into intact tissue. Further, antibodies to different pectin structures and confocal microscopy were used to visualize the localization of the modified pectin. These two techniques and this work were essential to document that the enzyme can be transported beyond the superficial outer layer. The ability to recover second grade products that are not table fruit into value added products is valuable to producers. Modified Pectins. Research showed not only that PME can make calcium sensitive pectin, but the mechanism of de-esterification by the two main PME isozymes in Valencia fruit was elucidated using NMR and ion exchange chromatography. This work helps explain the sporadic clarification of citrus juices in the absence of significant PME activity and allows
for the development of pectins tailored for specific applications. Preliminary work was conducted that will help as we use modified pectins to stabilize emulsions for controlled drug delivery.
Impacts
This research will have application for the use of pectins as ingredients in foods with known charge, charge distribution and size and will enhance the prediction of performance of pectin as an ingredient in foods. Physical stability of juices, juice beverages and fruits is moderated by pectinmethylesterase and pectin-protein interactions. PME can be used to tailor quality and moderate texture of juices, beverages and fruits.
Publications
- Banjongsinsiri, P., Ackerley, J.L. and Wicker, L. 2004. Detection of Vacuum Infusion of Pectinmethylesterase (PME) in Strawberry by Activity Staining. J. Food Sci. 69: 173-183.
- Banjongsinsiri, P., Kenney S. and Wicker, L. 2004. Pectinmethylesterase (PME) and Calcium Infusion and Texture of Minimally Processed Mango. J. Sci. Food Agric. 84: 1493-1499
- Kim, K. 2004. Valencia pectinmethylesterase Isozymes result in pectin of unique charge domain and functionality. Ph.D. thesis, May, 2004
- Kim, Y. and Wicker, L. 2004. Team led laboratories facilitate learning. Southern Region Teaching Symposium. May 20-22, Athens GA
- Wicker, L. 2004. Hydrocolloids and proteins, interactions and stabilization of dispersed food systems. Invited Keynote address to International Congress: Biotechnology in Developing Countries, June 20-23, 2004, Durango, Mexico. Invited.
- Wicker, L. and Y. Kim. 2004. Enzymatic Modification of Pectin to Produce Tailored Functional Stabilizer. International Congress: Biotechnology in Developing Countries, June 20-23, 2004, Durango, Mexico
- Kim, Y. and Wicker, L. 2004. Pectinmethylesterase Modification and Physico-Chemical Properties of Pectin. ACS Symp. August 20-23, Philadelphia, PA. Advances in Biopolymers: Molecules, clusters, networks and interactions. Invited
- Barnes, B.W., Corredig, M., Wicker, L. 2004. Aggregation and Separation of Acidified Milk Proteins and Pectin is Affected by Pasteurization of Dispersions. ACS Symp. August 20-23, Philadelphia, PA. Advances in Biopolymers: Molecules, clusters, networks and interactions. Invited
- Contreras-Esquivel, J.C., Montenez, J.C., Wicker, L. 2004. Extraction and Characterization of Pectins from Novel Sources. ACS Symp. August 20-23, Philadelphia, PA. Advances in Biopolymers: Molecules, clusters, networks and interactions.
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Progress 01/01/03 to 12/31/03
Outputs
Mixed juices or juice blends are often not stable upon blending or storage and causative factors are not clearly delineated. Whey protein concentrate was used to prepare protein fortified banana juice beverages and characterized during storage over a 60-day storage period. The particle volume and particle surface area mean diameter remained unchanged. Differences were detected for sedimentation and serum separation. The products remained light colored for 60 days, while red character, yellow character and saturation increased with time at elevated storage temperatures. The Hue was smaller at elevated temperatures. A sensory descriptive panel described the product as a sour, sweet, smooth beverage with distinctive banana flavor and minimum off-flavor. In model system studies, interactions between whey and pectin accounted for non-Newtonian behavior. Heat induced interactions also contributed to instability. Pectinmethylesterase (PME) is responsible for blockwise
de-esterification of pectin and is implicated in clarification of citrus juices and juice-containing beverages by initiating the formation of calcium reactive pectic acid. The cationic character of PME isozymes or the presence of PME-pectin complexes influences juice clarification and 13,000 and 27,000 peptides influence the rate of clarification of citrus juice. Valencia PME modifies the charge and charge distribution of pectin without loss of MW. Proteins at 13, 27, and 36 kDa, presumptively PME, influence not only clarification of juice, but also floc formation of soluble cloud components. In addition to clarification by precipitation of colloidal cloud constituents with insoluble calcium pectate, these results support the role of a non-catalytic protein interaction with cloud constituents and clarification by an additional mechanism, possibly the displacement of a protective colloid and aggregation of soluble constituents. Strawberries and mangoes were infused with exogenous PME
and activity of PME, change in texture and distribution of pectic substances was quantified. By developing a PME print technique, it was shown that PME was uniformly infused into strawberry halves. The localization of the enzyme in specific area of the strawberry fruit may impact on any overall firmness of strawberries. Firmness of non-infused and PME infused strawberries were greater than water infused strawberries. Infusion of PME with the vacuum technique may be a potential process aid to improve quality, particularly of strawberry pieces or purees. Mango cubes infused with Valencia orange PME and calcium chloride had greater gumminess and chewiness, but displayed no difference in firmness compared to mango cubes without treatment. AIS extracted from treated and untreated mangos was high in insoluble pectin and water soluble pectins had degree of esterification values less than 50%. The incongruity in pectin distribution and presence of a PME inhibitor, suggests that other
components in the cell wall, such as cellulose and hemicellulose, may contribute to softening or inhibition of firming by infusion of PME and calcium chloride.
Impacts
This research will have application for the use of pectins as ingredients in foods with known charge, charge distribution and size and will enhance the prediction of performance of pectin as an ingredient in foods. Physical stability of juices, juice beverages and fruits is moderated by pectinmethylesterase and pectin-protein interactions. PME can be used to tailor quality and moderate texture of juices, beverages and fruits.
Publications
- Kim Y. and Wicker, L. 2003. Valencia pectinmethylesterase modify charge and charge distribution of pectin. Institute of Food Technologists, Annual Meeting, Chicago, IL, July 12-16.
- Ackerley, J.L. and Wicker, L. 2003. Floc Formation and Changes In Serum Soluble Cloud Components Of Fresh Valencia Orange Juice. J. Food Sci. 68(4): 1169-1174.
- Frank, J., Ehlers, J., and Wicker, L. 2003. Removal of Listeria monocytogenes and Poultry Soil-Containing Biofilms Using Chemical Cleaning and Sanitizing Agents under Static Conditions. Dairy, Food and Environmental Sanitation, Food Protection Trends 23 (8): 654-663.
- Wicker, L., Ackerley, J.L., and Hunter, J.L. 2003. Modification of Pectin by Pectinmethylesterase and the Role in Stability of Juice Beverages. Food Hydro. 17: 809-814.
- Kazmierski, M., Wicker, L., Corredig, M. 2003. Interactions of beta-Lactoglobulin and Pectins in Acidified Systems. J. Food Sci. 68: 1673-1679
- Wicker, L. 2003. Stability of Juice Beverages as Affected by Pectinmethylesterase, ACS Symposium Series No. 871. Nutraceutical Beverages: Chemistry, Nutrition, and Health Effects, pp. 133-148, F. Shahidi and D.K.Weerasinghe, eds. American Chemical Society, Washington, D.C.
- Wicker, L., 2003. Frozen Citrus Juices. In: Handbook of Frozen Foods. Y. Hui, ed. and R. Botta, P. Cornillon, I. Guerrero, E. Venthumudu, M. Lim, K. Murell, assoc. eds., Marcel Dekker, Inc., pp. 483-497.
- Banjongsinsiri, P. 2003. Effect of Pectinmethylesterase and Calcium Infusion on Texture and Structure of Fruits and Vegetables. Ph.D. thesis under the direction of Dr. L.Wicker, University of Georgia, Athens, GA
- Koffi, E. 2003. Development of Cloud Stable Whey-Fortified Banana Beverages. Ph.D. thesis under the direction of Dr. L.Wicker, University of Georgia, Athens, GA
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Progress 01/01/02 to 12/31/02
Outputs
Orange juice concentrates are often used as a base in juice blends with other fruit juices, milk drinks and other juice beverages. Clarification of juices and instability of juice dispersions is a severe quality defect. Clarification of citrus juices by pectinmethylesterase, PME, at 4C was observed in the presence of cations within 1-2 days of storage. An additional mechanism for clarification of citrus juices was proposed: (1) bridging of cloud particles by a small population of highly de-esterified pectin molecules or by pectin molecules with a specific charge distribution and/or (2) displacement of a protective colloid from the cloud particle surface and coalescence of particles. Clarification of juices in the presence of cations and least cationic PME (27 kd) was most rapid. These results have implication for the need of quality assessment of water that is used to reconstitute juices with low levels of active PME or pasteurized juices that were inadvertently
exposed to PME before pasteurization. The results indicate that PME complexes with pectin and/or low-molecular-weight protein influence the ability of PME to induce clarification. In whey-fortified fruit beverages, attractive interactions occur between whey and high methoxyl pectin at low pH. Dispersions of three components (water, pectin, whey) or (banana juice, pectin, whey) were more shear thinning and had greater consistency coefficients than dispersions of two components (banana juice, pectin; banana juice, whey). The average particle sizes were not significantly different among the two or three component systems. Whey had smaller contribution to the consistency of the beverages. Knowledge about the interaction between high methoxyl pectins, whey proteins, and banana juice components will help modulate the textural performance of such ingredients in formulation of whey fortified banana beverages. Texture of fruits, like mango, may be improved using pectinmethylesterase. Mango
cubes infused with Valencia orange PME and CaCl2 had greater gumminess and chewiness but no difference in firmness of no treatment mango cubes. AIS extracted from treated and untreated mango were high in insoluble pectin. Mango (cv. Kent) firmness is most likely moderated by the change in solubility of large molecular weight, insoluble pectin and non-pectin cell wall components. Before development of soy cultivars with desirable production traits and functional properties, methods to test parental lines must be identified. Soybean cultivars, Danbaekkong and Benning, have different production, quality and functionality as soymilk and tofu. Soymilk from Danbaekkong has higher protein content, larger amount of glycinin (11S), more shear thinning than Benning. Danbaekkong tofu was harder, more chewy and gummy than Benning tofu. These differences between Dan and Ben are probably from the different protein content and composition, especially ratio of 11S to 7S.
Impacts
Interactions of proteins and pectins at low pH have a significant impact on rheological and stability properties of juices and juice beverages that are formulated for nutritional quality. Functional properties is correlated to proteins and relative ratios. Physical stability of juices, juice beverages and fruits is moderated by pectinmethylesterase and pectin-protein interactions. PME can be used to tailor quality and moderate texture of juices, beverages and fruits.
Publications
- Corredig, M. and Wicker, L. 2002. Juice Clarification by Thermostable Fractions of Marsh Grapefruit Pectinmethylesterase. J. Food Sci. 67:1668-1671.
- Wicker, L., Ackerley, J.A., Corredig. 2002. Clarification of Juice by Thermolabile Pectinmethylesterase is Accelerated by Cations. J. Agric. Food Chem. 50:4091-4095.
- Ackerley, J.L, Corredig, M., and Wicker, L. 2002. Clarification of Citrus Juice is Influenced by Specific Activity of Thermolabile Pectinmethylesterase and Inactive PME-Pectin Complexes. J. Food Sci. 67(7): 1-5.
- Ackerley, J.L. 2002. Clarification Of Valencia Orange Juice Is Influenced By Specific Activity Of Thermolabile Pectinmethylesterase, Inactive PME-Pectin Complexes And The Changes In Serum Soluble Components, M.S. Thesis, University of Georgia, Athens, GA.
- Hunter, J.L. 2002. Enzymatic Modification Of Pectin For Improved Functional Properties. M.S. Thesis, University of Georgia, Athens, GA.
- Ackerley, J.L., Wicker, L. Floc formation and changes in serum soluble cloud components of fresh Valencia orange juice. Institute of Food Technologists, 61th Annual Meeting, Anaheim, CA, June 15-19, 2002.
- Banjongsinsiri, P., Wicker, L. Modification of minimally processed texture of mango cubes. Institute of Food Technologists, 61th Annual Meeting, Anaheim, CA, June 15-19, 2002.
- Koffi, E. Wicker, L. Interaction of whey proteins with high methoxyl pectins in acidified banana beverages. Institute of Food Technologists, 61th Annual Meeting, Anaheim, CA, June 15-19, 2002.
- Kim, Y., Wicker, L., Soybean cultivars impact quality and function of soymilk and tofu. Institute of Food Technologists, 61th Annual Meeting, Anaheim, CA, June 15-19, 2002.
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Progress 01/01/01 to 12/31/01
Outputs
In 2001, the compostional factors related to instability of whey based beverages fortified with banana and mango purees was identified. A process was developed to assess the stability of these beverages and the optimal level of stabilizer was determined. In addition, pectinmethylesterase was evaluated for its role in stability of citrus juice and citrus beverages and its effect on pectin structure. A non-PME factor in juice clarification was proposed. Also, PME was evaluated as a method to improve texture of further processed fruits and vegetables. Methods for optimization of an infusion process and quantification of PME effect was developed.
Impacts
Protein fortified beverages have been developed that has unique blends of tropical fruit flavors and high in functional food components. Pectinmethylesterase was used as a process aid to improve the texture and acceptability of further process fruits.
Publications
- Corredig, M., Kerr, W.L., and Wicker, L. 2001. Particle Size Distribution of Orange Juice Cloud after Addition of Sensitized Pectin. J. Agric. Food Chem. 49: 2523-2526
- Ackerley, J.L., Corredig, M., Wicker, L. 2001. Clarification of citrus juice is influenced by specific activity of pectinmethylesterase (PME) and inactive PME-protein complexes. Institute of Food Technologists, 60th Annual Meeting, New Orleans, LA June 23-27, 2001.
- Koffi, E. and Wicker, L. 2001. Characterization of Cloud Components from Selected Tropical Fruits. Institute of Food Technologists, 60th Annual Meeting, New Orleans, LA June 23-27, 2001.
- Panida Banjongsinsiri, P., Ackerley J.L., and Wicker, L. 2001. Detection of Vacuum Infusion of Pectinmethylesterase in Strawberry by Activity Staining. Institute of Food Technologists, 60th Annual Meeting, New Orleans, LA June 23-27, 2001.
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