Considering the challenge of the global community in providing enough food for the growing population of the earth, and at the same time maintaining the existing ecosystem and since proteins are an essential part of human nutrition, as a result, protein supply is very important in terms of nutrition and environment. On the other hand, due to the fact that from a health point of view, excessive consumption of meat products as protein sources is not recommended, nowadays the need to produce alternatives for meat is seriously felt. Therefore, the aim of the current research is to create texture in vegetable protein isolated from soybeans in order to create an alternative to meat from animal sources. In this research, soy protein isolate powder was exposed to cold plasma with a voltage of 18 kV for 5, 10 and 15 minutes. The protein that was not under plasma was used as a control sample. The resulting samples were subjected to pH changes of 10 and 12, then free moisture, solubility, water holding capacity, emulsifying activity and emulsion stability, foaming capacity and foam stability, color, gel resistance, texture profile, rheology, free sulfhydryl, infrared spectroscopy with Fourier transform, scanning electron microscopy, electrophoresis, di-tyrosine amount and sensory eva‎luation were investigated. The results showed that due to the increase in plasma application time, the solubility, the amount of free d-tyrosine and sulfhydryl decreased (p<0.05). Also, the amount of hardness, chewability, elasticity, gumminess and stickiness were reduced. Further, with the increase in plasma time, it was observed that the foaming capacity and stability of the foam improved, and the emulsification ability and stability of the emulsions increased. Also, with the increase in plasma time, the scanning electron microscope images showed pores with more dispersion and irregularity and larger sizes. In colorimetry, it was found that the intensity of yellowness in the samples increased with the increase in plasma time and their brightness decreased. Also, with the increase in plasma application time, the free moisture in the samples increased until the surface of the samples that were subjected to plasma for 15 minutes were completely wet. In the comparison between pH 10 and 12, the solubility, free sulfhydryl, intrinsic fluorescent, and tissue properties were found to be lower in the samples with pH=12 than in the samples with pH=10. However, the foaming capacity and stability of the foam and its emulsifying ability and stability in these samples were more than the pH=10 samples. In general, it can be stated that increasing the duration of the cold plasma process and increasing the alkaline pH led to the weakening of the textural properties of soy protein isolate gels and the reduction of solubility, free sulfhydryl and intrinsic fluorescent, but the foaming and emulsifying properties and the water holding capacity were improved.

مهدي كديور

مهدي كديور , مهرنوش جعفري