Thermostability of probiotics and their α-galactosidases, and the potential for bean processing.

Soybeans and other pulses contain oligosaccharides which may cause intestinal disturbances such as flatulence. This study was undertaken to investigate α-galactosidase-producing probiotics added to frozen foods which can survive warming treatments used in thawing and consumption of the pulses. The maximum α-galactosidase activity (1.26 U/mg protein) was found in Bifidobacterium breve S46. Lactobacillus casei had the highest α-galactosidase thermostability among the various strains, with D values of 35, 29, and 9.3 minutes at 50°C, 55°C, and 60°C, respectively. The enzyme activity was less affected than viable cells by heating. However, the D values of two bacterial enzymes were lower than those of three commercial α-galactosidase-containing products. Freshly grown cells and their enzymes were more stable than the rehydrated cultures and their enzymes. Practical Application. Enzymes and cultures can be added to foods in order to enhance the digestibility of carbohydrates in the gastrointestinal tract. However since many foods are warmed, it is important that the thermostability of the enzymes be assessed. This paper provides data on the stability of α-galactosidase, which could potentially be added to food matrices containing stachyose or raffinose, such as beans.