The objective of this study is to determine the effects of barrel temperature and moisture content on the physicochemical properties of texturized vegetable protein (TVP). The water absorption index, water solubility index, texture, integrity index, color, and scanning electron micrograph of the TVP were analyzed. The extrusion conditions consisted of barrel temperature (110, 130, and 150oC) and moisture content (40, 45, and 50%) at a fixed screw speed of 250 rpm. The TVP extruded at 150oC barrel temperature and bearing 50% moisture content had higher water absorption index and water solubility index. Elastic force, cohesiveness, and color differences were the highest in the TVP extruded at 150oC barrel temperature and possessing 40% moisture content. However, the TVP at 150oC barrel temperature and having 40% moisture content had a lower integrity index than the TVP carrying moisture contents of 45 and 50%. The structure of the TVP extruded at 150oC barrel temperature and having 40% moisture content was found similar to a chicken breast tissue’s structure. In conclusion, 150oC barrel temperature and 40% moisture content are optimal conditional characteristics for the texturization of soy protein isolate and gluten.

The effects of temperature (150°C and 160°C) on physicochemical properties of extruded texturized vegetable protein with mealworm (0%, 15%) were studied. The extrusion process had a screw speed of 250 rpm, moisture content of 65%. The variation of formula was gluten content of 40% in 4 samples and none of gluten in 4 samples. As addition of mealworm increased and temperature increased, breaking strength and integrity index decreased, The nitrogen solubility index and protein digestibility increased as addition of mealworm increased and temperature decreased. DPPH radical scavenging activity significantly increased as addition of mealworm increased and temperature increased. On the contrary, the value of rancidity decreased as addition of mealworm increased even in 60 days. In conclusion, addition of mealworm became softer texture, and protein quality of the extruded texturized vegetable protein. The process promoting functionality such as improvement of antioxidant function was confirmed through this study. Also, adjusting temperature have an effect on protein content and antioxidation. The addition of gluten of 40% resulted in improving texture of TVP.

The present study aimed to investigate the effect of fermentation on physical properties of texturized vegetable protein (TVP) by using Bacillus subtilis. TVP was prepared by texturizing the mixture of isolated soy protein (50%), wheat gluten (40%) and corn starch (10%) with the use of twin-screw extruder at two different moisture contents (40% and 50%), 100 g min-1 feed rate, 200 rpm screw speed and 130°C die temperature. Then, TVPs were subjected to solid-state fermentation using B. subtilis at 37°C for 60 h. The texture (springiness, cohesiveness, chewiness and hardness), integrity index and color (lightness, redness and yellowness) of TVPs were determined before and after fermentation for 0, 12, 24, 36, 48 and 60 h, respectively. The springiness and cohesiveness did not change significantly after fermentation in all samples. However, chewiness and hardness decreased with increased fermentation time with the lowest values observed at 60 h after fermentation of TVPs (both 40% and 50% MC). Integrity index of fermented TVPs was significantly reduced while fermentation time was increased. Integrity index started to decrease significantly at 36 h after fermentation in TVP extruded with 40% MC. In another TVP (50% MC), the integrity decreased at 24 h after fermentation but it maintained higher integrity index than TVP (40% MC) throughout the whole fermentation period. The significant total color change was observed with increased fermentation time. During fermentation, lightness and yellowness decreased but redness increased significantly. This study pointed out that TVP fermented by B. subtilis still has good texture, and thus has the potential to become an attractive food for consumers who usually avoid fermented foods due to rotten appearance with no texture.

The comparison of physicochemical properties and cell structure of texturized vegetable protein (TVP) and different types of meats (beef, pork, and chicken samples) were studied. TVP from the blend of 40% isolated soy protein (ISP) and 60% wheat gluten (WG) was texturized with a twin-screw extruder at 100 g/min feed rate, 45% moisture content, 250 rpm screw speed and 140℃ die temperature. The nitrogen solubility index, integrity index, chewiness, longitudinal cutting strength and microstructure of TVP were similar to the chicken sample, when compared to the other meats. However, water absorption capacity (WAC) of TVP (217.38%) was significantly (P<0.05) higher than those of meat samples (109.53 to 165.35%). The microstructure of TVP showed the fibrous structure. Non-uniform air cells were observed in the microstructure of TVP, which could indicate high WAC. The study demonstrated that the physicochemical and cell structure of TVP from the blend 40% ISP and 60% WG with 45% moisture extrusion process was similar as chicken sample.