The impact of chymosin and plant‐derived proteases on the acid‐induced gelation of milk

Abstract

This work aimed to study milk gel formation during a slow fermentation process and the simultaneous action of different proteases like bovine chymosin, recombinant camel chymosin, ficin and bromelain. The acid-induced gels with bovine chymosin and recombinant camel chymosin were firmer than the control gels without proteases or the gels added with plant proteases. However, the acid-induced gels with chymosins had a considerable water release and shrunk in volume as the milk fermentation progressed. In contrast, the acid-induced gels added with bromelain and ficin were softer and showed less syneresis, even at acidic pHs.

Milk-Gelling Properties of Proteases Extracted from the Fruits of Solanum Elaeagnifolium Cavanilles

“…The kinetic of caseins hydrolysis by trompillo proteases (at 30°C and pH 7) is showed in Figure 4 . Other plant-derived proteases like ficin (from fig tree latex), dubiumin (from Solanum dubium fruits), and papain (from papaya fruit) have also shown superior proteolytic activity than chymosins [ 30 , 33 ]. Overall, it has been well documented that most plant-derived proteases have an intense caseinolytic activity, contrasting with the low proteolytic activity of chymosins [ 4 , 7 ].…”

“…trompillo proteases had greater milk-clotting activity (MCA) than other plant-derived proteases such as ficin, bromelain [ 30 ], and dubiumin [ 32 ]. However, the proteases from trompillo fruits had a much lower capacity to clot the milk than the recombinant and calf chymosins ( Table 2 ).…”

“…Few plant proteases can induce milk gelation, though these vegetable coagulants usually present a very low ratio of milkclotting activity to proteolytic activity (MCA/PA) [7,12,43]. The MCA/PA ratio for trompillo proteases was more prominent than reported for other plant proteases like ficin and bromelain [30,44] but lower than observed in the recombinant camel chymosin or the chymosin from the calf stomach (Table 2). These large MCA/PA ratios indicate that chymosins produce a very low (and specific) proteolysis on milk proteins, which induces the coagulation of a large volume of milk [45].…”

“…Then, the tubes were centrifuged for ten minutes at 10°C and 300 × g. The volume of whey released after centrifugation was measured and weighted. Syneresis was expressed as the relative percentage of whey released from the milk gels after 80 minutes of incubation [ 30 ]. Protein content in the whey released by the milk gels was analyzed by Bradford's method [ 26 ].…”

Crystallization of Lactose–Protein Solutions in the Presence of Flavonoids

“…The final protein concentration was measured with the Bradford method described elsewhere. 31 The presence of α-lactalbumin (αLA) and β-lactoglobulin (βLG) was corroborated by polyacrylamide gel electrophoresis (SDS-PAGE) 32 (Supplementary Figure 1).…”