Mashing of Rice with Barley Malt Under Nonconventional Process Conditions for Use in Food Processes

Non-conventional mashing conditions are relevant in the development of a lactic acid-fermented soymilk beverage where mashed rice is the source of carbohydrates for the fermentation and sweetness of the beverage. Advantages in the process layout could be achieved by mashing at higher pH and lower malt concentrations than normally used in the brewing industry. The work reported here assessed the consequences of mashing under non-conventional conditions. Malt concentration in the cereal part was varied from 25% to 70% (w/w), pH was varied within 5.3 to 7.1, and prolongation of the holding times at 50 degrees C and 62 degrees C was investigated. Regression equations have been established for predicting yields of soluble protein, low molecular weight sugars and total fermentability as functions of pH and malt concentration. The results showed that the maltose yield was constant while glucose, maltotriose and total fermentable sugar yields decreased slightly with increasing pH and decreasing malt concentration. Prolonged mash holding times at 50 degrees C and 62 degrees C gave minor increases in protein yields only. It is concluded that it is quite acceptable to use nonconventional mashing conditions when a mashing step is integrated in other food processes.