Extraction and Isolation of Cricket Protein Isolate with Ammonium Sulfate Addition Method and Its Effect on The Functional Properties of The Proteins

Cricket insect contains a high quality of protein. To be able to use the proteins in food industry, extraction and isolation steps are necessary to elevate the protein content. The objective of this study was to extract and isolate protein of cricket insect and to assess its functional properties. The extraction and isolation steps were carried out by using alkaline extraction-acid precipitation (AEAP) with varying concentrations of ammonium sulfate (0, 20,40, and 60% w/v). It was found that extraction method with 60% ammonium sulphate inclusion showed the highest yield and obtained maximum protein content (92.41%), which could be characterized as cricket protein isolate (CPI). This extraction and inclusion of ammonium sulphate affected physicochemical properties, including water holding capacity, oil holding capacity, emulsifying properties, and foaming properties of CPI. In conclusion, the extraction, isolation, and addition of ammonium sulfate could be used for isolating the CPI containing high protein content and can be further used in food manufactures as an alternative protein in the future

Deamidation of soy protein by protein-glutaminase: Process evaluation and effect of deamidation on protein functional properties and flavor-protein interactions

Flavor is a major determinant of the consumer acceptance of a food product. The availability of a flavor compound for sensory perception is greatly influenced by its interaction with non-volatile food constituents including fats, carbohydrates and proteins. The binding of flavor compounds to soy protein can be problematic since it can lead to flavor fade (loss of flavor or lowering flavor intensity) and hence a decline in product quality. These flavor-protein binding interactions can be altered by changing the conformation of the proteins. While chemical deamidation of soy protein isolate was previously found to decrease flavor-protein binding, the use of an enzymatic method for deamidation is generally more desirable since it is substrate specific, can be conducted under mild reaction conditions, and is perceived as natural and safe. Optimization of the enzymatic deamidation of soy protein isolate (SPI) by protein-glutaminase (PG) was successfully carried out using response surface methodology (RSM) to obtain a deamidated SPI with high degree of deamidation (DD) and an acceptably low degree of hydrolysis (DH). The deamidated SPI had enhanced solubility in both acidic and neutral conditions, improved emulsification properties, increased foaming capacity, but decreased foaming stability over the resting time. The effects of PG deamidation on flavor binding properties of SPI under aqueous conditions were evaluated by a modified equilibrium dialysis technique. It was found that partial deamidation (43.7% DD) decreased overall binding affinity for selected carbonyl containing flavor compounds (vanillin and maltol). The thermodynamic parameters of binding indicated that the flavor-protein interactions were spontaneous and that the nature of the interactions shifted from entropy to enthalpy driven after deamidation. Deamidation of soy protein appears to change the mechanism of binding from hydrophobic interactions and/or covalent bonding (Shiff-base formation) to weaker van der Waals forces or hydrogen bonding. The effect of PG deamidation on protein solubility and flavor binding potential of soymilk was studied. The sensory characteristics on aroma of deamidated soymilk (DSM) did not differ from those of the control soymilk (treated without PG; CSM). Protein solubility in the DSM was enhanced at weakly acidic conditions (pH 5.0). DSM had lower flavor binding potential than the CSM as evidenced by the fact that the odor detection thresholds for the flavor compounds vanillin and maltol were approximately 5 and 3 fold lower, respectively, in DSM than in CSM. The sigmoidal relationship of dose-response curves relating concentration of flavor compounds to aroma intensity demonstrated that DSM had lower flavor binding potential than CSM. The n exponents from Stevens’s power law indicated that vanilla and cotton candy intensities increased, as a function of vanillin or maltol concentration, at a higher rate in DSM than in CSM. The findings of this study can lead to the development of technology to produce proteins with improved functional properties and potentially decreased problems associated with flavor-protein interactions, especially with carbonyl containing flavor compounds. The information about binding mechanisms caused by modification of binding sites in protein by PG will allow the food industry to produce protein ingredients, from soybean as well as from other sources, with improved functional properties and potentially decreased flavor fade problem, especially for use in acidic protein-fortified foods and beverages

Effect of drying techniques on the stability of volatile compounds and antioxidative activities of dried Thai fermented black soybean (thua nao)

Thua nao, a traditional fermented soybean product in Thailand, is widely consumed as a plant-based food or a condiment due to its distinct flavor, taste, and nutritional benefits. In this research, thua nao samples were produced from black soybeans. After fermentation, various drying methods, including sun drying (SUN), hot air drying (HOT), microwave vacuum drying (MIC), and vacuum drying (VAC) were employed to produce dried thua nao. The dried samples were stored under ambient conditions for 8 months. Results revealed lipid oxidation and the Maillard reaction occurred during storage, leading to a decline in bioactive compounds and antioxidant activities. Volatile aroma compounds were analyzed using solid-phase microextraction coupled with gas chromatography-mass spectrometry, while principal component analysis (PCA) evaluated aroma profile changes during storage. PCA indicated that HOT, MIC, and VAC -treated samples remained stable for up to 4 months, while SUN-treated samples changed after 2 months. It was found that SUN treatment prominently promoted the formation of oxidized volatile compounds associated with fatty-waxy and green attributes. The HOT treatment contributed more to aroma volatile compounds associated with nutty-roasted, floral, woody-smoky, and sweet attributes. While, both MIC and VAC treatments showed a noticeable loss of aroma volatile compounds, they retained higher level of bioactive compounds compared to the other treatments. This information aids in selecting suitable drying techniques for thua nao products and enhances understanding of chemical transformations induced by drying