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Microbial Strategies for the Decolorization and Degradation of Distillery Spent Wash Containing Melanoidins
Published in M.H. Fulekar, Bhawana Pathak, Bioremediation Technology, 2020
Reports have shown that the caramels derived from sucrose have been used commercially in food industries as a pigment agent (Myers and Howell, 1992). The reaction between proteins and sugars at high temperature yields a small amount of caramel. It is a brownish black and viscous fluid with a high molecular weight that may be greater than 10 kDa. Dehydration of monosaccharides to reactive groups creates a complex polymerization between them and produces a number of reaction series. While sugars are boiled at high temperature as well as acids and bases catalyzing that reaction, the caramelization reaction arises. In the sugar production mode, the caramels are shaped when the sucrose treacle is elevated above 210°C, predominantly in the crystallization stage, when crystals of sugars come in close contact with hot planes, vessels or containers (Arimi et al., 2014).
Reaction Kinetics in Food Systems
Published in Dennis R. Heldman, Daryl B. Lund, Cristina M. Sabliov, Handbook of Food Engineering, 2018
Ricardo Villota, James G. Hawkes
Destruction of the previously reported pigments is of great significance to the food industry, due to loss of visual appeal and their bioactive components. In addition, the formation of undesirable color or pigments is also of great importance. In fact, browning compounds may alter the color, flavor, aroma, and nutritional value of food products. Three important pathways may be involved in browning development, namely, sugar caramelization, Maillard reaction, and oxidation of ascorbic acid. The heat-induced caramelization of sugars may occur under acidic or alkaline conditions and is associated with the production of flavors with unique characteristics, some of which have bitter or burnt notes. It should be pointed out that this reaction is the basis for commercially produced caramel colors and flavors and has been used by the industry for over 150 years. There are four classifications (designated I-IV) for caramel colors based on the carbohydrate and type of reactants used. There have been past concerns on potential carcinogenicity of some of the reaction compounds produced, particularly in classes III and IV, such as 4-Mel (4-Methylimidazole) and THI (2-acetyl-4-tetrahydroxybutyl imidazole); however, as of 2014, with strict control for usage levels, there has been no ruling otherwise to deem these to be unsafe (Vollmuth, 2018). Since class III and IV utilize an ammonia-based reactant, formation of 4-Mel is a consequence of a Maillard-type reaction. The Maillard reaction involving the condensation of amino groups with reducing sugars can also contribute to serious problems during the processing and storage of food products. The Maillard reaction has been extensivel y characterized and found to be highly influenced by temperature, water activity, and pH. On the other hand, the degradation of ascorbic acid has also been found to be of great significance in the darkening of a number of products including fruit juices and concentrates. Although the mechanism of decomposition of ascorbic acid is rather complex as previously discussed, its decomposition has been found to be accompanied by the production of carbon dioxide.
Influence of pulse-spouted infrared freeze drying on nutrition, flavor, and application of horseradish
Published in Drying Technology, 2021
Chunning Luan, Min Zhang, Arun S. Mujumdar, Yaping Liu
Color is the most commonly used evaluation index of dry food products, and it is direct reflection of the perceived quality of dry products.[21] Fruits and vegetables have different colors, mainly due to the presence of anthocyanins, chlorophylls, carotenoids, and other colored substances in cells. Therefore, the loss of color in dried products also reflects the loss of nutrients in fruits and vegetables.[22,23]Table 1 showed the values of L*, a*, b* of different drying methods of horseradish, which represent brightness, red/green value, and yellow/blue value, respectively. It can be seen from the table that FD samples had the highest L* value and the lowest b* value. There was no significant difference between the values of L*, a*, b* of PSIRFD samples and FD samples, indicating that the color of the products obtained by the two drying methods was similar. The color of HAD and IRHAD samples changed greatly, with L* value decreased and b* value increased, which was consistent with the results observed by the naked eye (as shown in the picture). As for the color difference values between dried samples and fresh samples, the ΔE of PSIRFD samples was the smallest, followed by FD, HAD and IRHAD. The reason may be that horseradish has some reactions in the process of HAD and IRHAD, such as pigment degradation, caramel reaction, and Maillard reaction.[13,24,25] The low temperature and vacuum environment in the drying process of FD and PSIRFD effectively prevent these reactions.
Effects of main drying temperature on drying characteristics and quality of freeze-dried scallion (Allium fistulosum)
Published in Drying Technology, 2023
Qiaolan Sun, Zezhi Wang, Li Chen, Cunshan Zhou, Clinton Emek Okonkwo, Yuxin Tang, Aiping Lu, Qiaomin Lu
During the drying process, the product color changes to a certain extent due to the influence of drying temperature, drying time, and drying pressure. Figures 2c,d shows the ΔE and whiteness value between dehydrated and fresh scallions after scallions were dried at different main drying temperatures. It can be seen from the figure that the whiteness values of the dehydrated scallion sample increased significantly when compared with the fresh scallion. This may be because the vacuum and low-temperature environment of VFD isolates the contact between oxygen and scallion and reduces the enzyme activity, thus inhibiting a series of oxidation reactions and enzymatic browning during drying.[12] As can be seen from Figure 2c, the difference between the 4 °C, 25 °C, and VT groups was not significant, but was significantly different from the −20 °C group. On the one hand, the temperature of −20 °C is relatively low, and this ensures that the ice crystal inside the scallions will not melt during the drying process, making the water of the scallions sublimate directly during the drying process and maintaining the integrity of the cell structure. On the other hand, it makes the dehydration process of scallion slow, and the internal and external pressure difference is more balanced. At the same time, low temperature better inhibits Maillard reaction, caramel reaction, and enzymatic browning. As can be seen from Figure 2d, in the VFD group, the whiteness value of the −20 °C group was the smallest. There was no significant difference between the 25 °C group and 4 °C groups, and it has the highest whiteness value. This phenomenon may be related to the drying time. The shorter the drying times the lesser the enzymatic browning time. Although the drying temperature of −20 °C group was low, which inhibits enzymatic browning to a certain extent, long-term drying will prolong the enzymatic browning time, causing excessive browning, and reduce the whiteness value of the product. Compared with the 4 °C group, the 25 °C group had a shorter drying time, but its drying temperature was higher, the enzymatic browning process was more intense, and finally showed the same whiteness value as the 4 °C group.