RESUMEN
The texture of soybean protein-based products is primarily influenced by the aggregation and gel morphology of the protein, which is modulated by manufacturing factors. Interactions involved in protein morphology changes include disulfide bonds, hydrophobic interactions, electrostatic interactions, and hydrogen bonds. Notably, an interaction perspective probably provides a new way to explaining the aggregation and gel morphology, which could help overcome the hurdle of developing a textured product. Based on the interaction perspective, this review provides detailed information and evidence on aggregation, conformational stability, and gel network morphology of soybean protein and its components induced by pH, NaCl, and temperature. pH-induced electrostatic interactions and hydrogen bonds, NaCl-induced electrostatic interactions, and temperature-induced hydrophobic interactions and disulfide linkages are the main motivations responsible for changes in soybean aggregation and gel morphology. By reducing the proportion of strong-interactions, such as disulfide linkages and hydrophobic interactions, and increasing the proportion of weak-interactions, such as electrostatic interactions and hydrogen bonds, the protein total surface area expands, indicating increased conformational stretching and decreased cohesion. This possibly results in reduced hardness and increased toughness of textured proteins. The opposite effect can be observed when the proportion of strong interactions is increased and that of weak interactions is decreased.
Asunto(s)
Interacciones Hidrofóbicas e Hidrofílicas , Agregado de Proteínas , Cloruro de Sodio , Proteínas de Soja , Temperatura , Proteínas de Soja/química , Concentración de Iones de Hidrógeno , Cloruro de Sodio/química , Geles/química , Enlace de Hidrógeno , Electricidad Estática , Glycine max/química , Conformación ProteicaRESUMEN
This study investigated the relationship between nitrogen soluble index (NSI), bulk density, gel storage modulus of soybean protein isolate and torque during high-moisture (50%) extrusion, and analyzed the influence to extrudate texture by the moisture content and the expansion degree of extrudate. The results showed that in the range of NSI of 21-74%, bulk density of 0.41-0.47 g/cm3 , and gel storage modulus of 3,800-5,400 Pa, the torque and specific mechanical energy raised with the decrease in NSI and the increase in bulk density and gel storage modulus. The lower the moisture content of the extrudate was, the higher its hardness. Interestingly, as the extrudate expands, bubble cavities formed on the surface of the extrudate could cause its hardness to drop from 13,124 g/s to 11,736 g/s and 4,840 g/s. Overall, the hard extrudates can be produced from soy protein isolates with low NSI (<21%), high bulk density (>0.47 g/cm3 ), and gel storage modulus (>5,380 Pa) via high-moisture extrusion, at the same time appearing in an expanded structure that reduces the hardness test value of the extrudate.
Asunto(s)
Manipulación de Alimentos , Proteínas de Soja , Manipulación de Alimentos/métodos , Solubilidad , TorqueRESUMEN
To provide additional evidence and better understand the high-moisture texturing extrusion process of soybean protein isolate (SPI), the physico-chemical changes of SPI during extrusion were investigated. SPI in the extruder feeding zone, barrel zones 1 (80 °C) to 4 (135 °C), and the cooling die (80 °C) were obtained from a dead-stop operation. The lowest values associated with the denaturation enthalpy and the extractable protein occurred in zone 3 (150 °C). The minimum level of the protein subunit content was identified in zone 4. The highest value of the average protein molar mass occurred in zone 3. The ß-sheet ratio in the protein increased, and the unordered ratio decreased after extrusion. The surface hydrophobicity of the protein decreased with water injection in zone 1; however, it increased in zone 2 (110 °C). Overall, SPI undergoes swelling, denaturation, aggregation, and depolymerization due to water injection, heating, and shearing during high-moisture extrusion.
Asunto(s)
Proteínas de Soja , Agua , Interacciones Hidrofóbicas e Hidrofílicas , Peso Molecular , Agua/químicaRESUMEN
BACKGROUND: Ginger stem (GS) is a by-product of ginger processing. It is not directly edible as a feed or food, which leads to it being discarded as waste or burned. Accordingly, it is very important to develop new functional products in the food or feed industry as a result of high nutritional and medicinal values. In the present study, the structures and physicochemical properties of GS powders of different sizes were evaluated after ultrafine grinding by a vibrating mill. RESULTS: The ultrafine powders exhibited a smaller particle size and uniform distribution. Higher values in bulk density (from 1.07 ± 0.06 to 1.62 ± 0.08 g mL-1 ), oil holding capacity (from 3.427 ± 0.04 to 4.83 ± 0.03 g mL-1 ), and repose and slide angles (from 42.33 ± 1.52 to 54.36 ± 1.15° and 33.62 ± 0.75 to 47.27 ± 1.34°, respectively) of ultrafine GS powders were exhibited compared to coarse powders. With a reduced particle size, the solubility of ultrafine powders increased significantly (P < 0.05), whereas the water holding and swelling capacities decreased with a reduced particle size and then increased. Fourier transform infrared spectroscopy analysis showed that ultrafine grinding did not damage the main cellular structure of GS powder. The reduction of fiber length and particle size in GS was observed by light microscopy and scanning electron microscopy. The X-ray diffraction patterns demonstrated the crystallinity and the intensity of the peak in superfine GS powders. CONCLUSION: The present study suggests that ultrafine grinding treatments influence the structures and physicochemical properties of GS powders, and such changes would improve the effective utilization of GS in the food or feed industry. © 2020 Society of Chemical Industry.