In recent years much attention and interest have been directed toward application of natural antimicrobial agents in foods. Some naturally occurring proteins such as lactoperoxidase, lactoferrin, and lysozyme have received considerable attention and are being considered as potential antimicrobial agents in foods. Lysozyme kills bacteria by hydrolyzing the peptidoglycan layer of the cell wall of certain bacterial species, hence its application as a natural antimicrobial agent has been suggested. However, limitations in the action of lysozyme against only Gram-positive bacteria have prompted scientists to extend the antimicrobial effects of lysozyme by several types of chemical modifications. During the last 2 decades extensive research has been directed toward modification of lysozyme in order to improve its antimicrobial properties. This review will report on the latest information available on lysozyme modifications and examine the applicability of the modified lysozymes in controlling growth of Gram-positive and Gram-negative bacteria in foods. The results of modifications of lysozyme using its conjugation with different small molecule, polysaccharides, as well as modifications using proteolytic enzymes will be reviewed. These types of modifications have not only increased the functional properties of lysozyme (such as solubility and heat stability) but also extended the antimicrobial activity of lysozyme. Many examples will be given to show that modification can decrease the count of Gram-negative bacteria in bacterial culture and in foods by as much as 5 log CFU/mL and in some cases essentially eliminated Escherichia coli. In conclusion this review demonstrates that modified lysozymes are excellent natural food preservatives, which can be used in food industry.

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The aim of this study was to find empirical models for some properties of bread dough as a function of bran concentration and particle size using D-Optimal made by Design Expert Software. Wheat flour was replaced with 0, 5, 10, 15 and 20% (w/w, flour basis) wheat bran at particle sizes of 170, 280, 425 and 750 μm. Increasing bran concentration and particle size enhanced dough water absorption. Dough arrival and development times increased, while dough stability time, tolerance to mixing and volume rising decreased as the bran particle size and concentration increased. The dough became darker, more reddish and yellower with increasing bran concentration and particle size. Dough hardness increased while cohesiveness decreased with addition of bran concentration and particle size. In general, strong correlations between dough properties with bran quantity and particle size were established. Bran concentration had stronger effect on dough properties compared to its particle size.

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The purpose of this investigation was to study the effect of actinidin, the proteolytic enzyme from kiwi fruit, on protein solubility (nitrogen solubility index, NSI) and sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS‐PAGE pattern of soymilk proteins. Actinidin from kiwi fruit was purified to homogeneity by precipitation with salt at pH 5.5 followed by anion exchange chromatography on a diethyl amino ethyl‐Sephadex column. Actinidin significantly (P < 0.05) increased NSI of soymilk in a dose‐dependent manner. A 40% increase in NSI was obtained when 0.8 unit of actinidin/mL soymilk was used. Higher level of enzyme resulted in a decrease in the NSI and formation of a gel‐like structure. SDS‐PAGE results showed increase in the intensity of several protein bands with molecular weights in the range of 16–20 kDa and 30–42 kDa in actinidin‐treated soymilk. The results of this study indicate that higher solubility of soymilk proteins can be achieved by limited proteolysis using actinidin. Since solubility is a major quality attribute, actinidin can be used to improve the functionality of soymilk and extend the applicability of soymilk as an ingredient in other food products. PRACTICAL APPLICATIONS In this study, the effect of application of proteolytic enzyme actinidin from kiwi fruit in solubilization of soymilk proteins was confirmed. Since nutritional and functional properties of proteins usually require a protein with a relatively high degree of water solubility, the results of this study shows that actinidin can be used to improve nutritional attributes as well as the functionality of soymilk (such as emulsifying property, water‐holding capacity, etc.) in different foods.