Browsing by Subject "Maillard reaction"
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Item Hypoallergenization of soy protein using a combination of limited enzymatic hydroylsis and controlled Maillard-induced glycosylation(2014-05) Walter, Jordan KayEmerging interest among consumers as to the health benefits of soy and a shifting preference toward more economical sources of protein has led to the increased global interest in soy protein. However, the main drawback to the expanded use of soy protein is its allergenicity, as soy is listed among the "Big 8" food allergens by the Food and Drug Administration (FDA). Therefore, in order to prevent a decrease in the momentum behind the usage of soy protein ingredients, different protein modification techniques must be explored in order to reduce the allergenicity of soy. Extensive enzymatic hydrolysis can reduce the allergenicity of a protein. However, this technique has negative consequences such as decreased protein functionality and bitter flavor. In order to limit enzymatic hydrolysis, response surface methodology (RSM) can be used to determine the optimized combination of factors, such as time, temperature and enzyme to substrate ratio, that results in the maximum reduction in immunoreactivity of the modified protein, while maintaining quality. Enzymatic hydrolysis, however, when limited, may only reduce the immunoreactivity to a certain extent. Thus a second technique, such as Maillard-induced glycosylation may further reduce the allergenicity of the minimally hydrolyzed soy protein. The first objective was to determine optimal hydrolysis conditions for a maximum reduction of soy protein allergenicity using response surface methodology. The second objective was therefore to determine the effect of limited and controlled Maillard-induced glycosylation on the allergenicity of soy protein hydrolysate produced under optimized conditions from objective 1. A central composite design (CCD) was used to produce different soy protein hydrolysate (SPH) samples using Alcalase 2.4L with 3 independent variables; temperature (x1), time (x2), and enzyme to substrate ratio (E:S) (x3), with the degree of hydrolysis (DH) and the % reduction in immunoreactivity as the response variables. Western blots and ELISA were used to evaluate the immunoreactivity of the different hydroylsates using sera from different soy allergenic individuals. The design included 20 experimental units with 6 center points to assess experimental variability, 8 factorial points, and 8 alpha points to assess potential curvature in the data. The effects of the different independent variables on the responses were assessed by fitting the data to the appropriate model. Once a model was selected, 3D plots were generated. Once all of the responses were fit to the appropriate models, constraints were then added onto the levels of the variables that resulted in a DH greater than 8%. The predicted % reductions in immunoreactivity were then determined for each individual sera with the added constraints. Due to overlap in the predicted optimum response among the sera, one set of conditions was chosen to produce one optimized hydrolysate. Maillard-induced glycosylation of the optimized hydrolysate was conducted using conditions that were carefully selected to control the reaction. Several different measurements were done to assess the progression of the reaction, including Amadori compound formation, browning, lysine blockage, and fluorescence, all of which confirmed limited progression of the reaction. The immunoreactivity of SPH, partially glycosylated soy protein hydrolysate (PGSPH), and partially glycosylated soy protein (PGSP) was determined using ELISA and Western blots. Significant reductions in immunoreactivity (up to 58%) were observed for the different hydrolysates produced using RSM. Variability among sera was observed for the different hydrolysates, which was attributed to the resulting protein and protein/peptide profile upon hydrolysis. Different hydrolysis conditions may have resulted in the exposure or elimination of IgE binding regions (epitopes). Using RSM modeling, the optimized hydrolysis conditions were determined and the resulting SPH had a DH of 7.8% and a % reduction in immunoreactivity ranging from 20-52%. When the produced SPH was subjected to controlled Maillard-induced glycosylation, a significantly (P ≤ 0.05) higher % reduction in immunoreactivity (up to 83%) was observed when using serum that had the highest soy specific IgE (45.30 kU/L). Results from this work, for the first time, showed that two different protein modification techniques can be utilized in combination to substantially reduce the allergenicity of soy protein while maintaining quality. Therefore, limited enzymatic hydrolysis combined with controlled Maillard-induced glycosylation has great potential for the development of hypoallergenic protein ingredients.Item Storage stability of a commercial spray dried hen egg yolk powder(2016-03) Guo, MufanDehydration is a good process approach for food preservation. However, dried food products may still suffer from deterioration if store in an abused environment such as high humidity (water activity (aw) > 0.6) and/or high temperature (> 45°C). These storage conditions can induce undesirable chemical reactions (disulfide bond interactions, Maillard reaction and/or lipid oxidation), resulting in a significant decrease in food quality. In this study, the storage stability of a commercial spray-dried egg yolk powder was evaluated. The dried egg yolk powder (DEY) was stored at three temperatures (room temperature, 35°C, and 45°C) and at six aw (0.05, 0.12, 0.37, 0.44, 0.54, 0.66) for at least two months, and several physicochemical changes and extent of protein aggregation were measured. The overall color change of DEY was that it became slightly darker (decrease of L* value), more red (increase of a* value), and less yellow (decrease of b* value) with increased storage time. The reaction kinetics of the L* value of DEY was also calculated using a first-order hyperbolic model. Its Q10 (rate increase with temperature increase at 10°C) was 2.9, which was more indicative of lipid oxidation, and the Ea (activation energy) was around 83 kJ/mole. The color change was mostly due to the browning pigments that were produced from the Maillard reaction and lipid oxidation. The glucose content went to zero after one-week during storage at 45°C at an aw of 0.66, confirming the occurrence of the Maillard reaction. The peroxide value of DEY storage at 45°C at aw of 0.66 was significantly increased compared to the control (vacuum packaged at -20°C), proving the occurrence of lipid oxidation. In addition, the Maillard reaction products and lipid oxidation products were both detected using the front face fluorescence spectrometer. After storage at an aw of 0.66 at 45°C for 8 weeks, protein solubility of DEY in TBS-SDS buffer [Tris-buffered saline (TBS: 20 mM Tris and 500 mM sodium chloride, pH 7.5) containing 1% sodium dodecyl sulfate (SDS, g/ml)] decreased to ~ 78% compared with that of the original DEY. Formations of buffer-soluble and –insoluble protein aggregates were discovered using SDS-PAGE. The protein aggregates were mainly formed through unfolded intermediates and unfolded states as well as direct chemical linkages. The proteins in DEY were all denatured after storage at an aw of 0.66 at 45°C for 8 weeks, resulting in numerous unfolded intermediates and states that could interact with each other to form aggregates. The spray drying process during the manufacturing of DEY also caused denaturation of protein, which explained the detection of buffer-insoluble protein aggregates in the original sample. Increases of disulfide bond links and protein-lipid interaction during storage were also found using techniques such as Raman spectrometry, fourier transform infrared spectroscopy, and front-face fluorescence spectrometry, indicating that some of the protein aggregates were induced by chemical reactions. The high molecular weight protein aggregates (HMWPAs) were further evaluated. Results showed that 32 proteins were involved with formation of buffer-soluble and -insoluble HMWPAs. They were products of natural egg yolk proteins and egg white proteins including serum albumin, vitellogenin, apovitellenin, as well as ovotansferrin, ovalbumin, lysozyme, ovomucoid, and ovastatin. Most of them contain disulfide bonds and some of them contain ligand and fatty acid binding sites, which corresponded with the theory of the direct chemical linkages induced protein aggregates. Overall, physicochemical changes and protein aggregates were found during the storage of DEY and it is mostly due to three undesirable chemical reactions, i.e., disulfide bond interactions, the Maillard reaction and/or lipid oxidation. Therefore, most effective approaches to reduce and/or inhibit the occurrence of those reactions include adjusting storage temperature and humidity as well as vacuum packaging after drying.Item A Systematic Literature Review of Acrylamide Levels, Adverse Health Effects, and Reduction of Formation in Fried and Baked Potato Products(2023-05-01) Branco, Emile C.K.Acrylamide is a processing contaminant produced by the Maillard reaction at high temperatures, such as baking or frying. The Maillard reaction is also what creates the brown or caramelized color on the outside of food when going through these processes. Fried and baked potato products are one of the highest acrylamide producers in the food industry. Food researchers have proven the presence of acrylamide in this everyday food through studies which will get higher as the temperature gets higher and the length of time frying or baking gets longer. There are links between dietary acrylamide accumulation in the body and various cancers, reproductive issues, and neurological damage. Some discoveries and developments may help reduce acrylamide in potatoes, starting from pre-harvesting to post-processing. Given the high levels of acrylamide in potato products, research suggests additional monitoring of acrylamide in food products and their consumption.