Plants represent an attractive source of milk-clotting proteases with potential use for chymosin substitution in cheesemaking process.
A crude enzymatic extract from B. pinguin fruit showed capacity to clot milk efficiently in a short time. It showed a maximum milk-clotting activity around 4 U/mL in the range of 70-80 ºC. This value indicated that one mL of the extract was capable to clot around 400 mL of milk in 40 min at the specified condition. B. pinguin extract presented only 25% of its maximum activity under standard temperature (30-35 ºC) for cheese-making. Proteases inhibitors indicated that cysteine and serine proteases were present in the extract and could be responsible for the milk-clotting activity found. SDS-PAGE analysis of casein hydrolysis indicated that proteases in B. pinguin extract were more proteolytic than chymosin. The high presence of milk-clotting proteases in B. pinguin fruit offers an alternative new source of proteases for biotechnological processes.