The effects of camel chymosin and Withania coagulans extract on camel and bovine milk cheeses

Abstract

Withania coagulans (W. coagulans) extract and camel chymosin have aspartic protease capable of coagulating milk for cheese production. This study investigated the quality of camel and bovine milk cheeses coagulated using Withania extracts, came chymosin, and their mixture in two experiments. In Experiment (1), a factorial design with four factors (W. coagulans, camel chymosin, incubation time, and incubation temperature) was performed. The effect of these factors on cheese's yield and hardness were assessed. An enzyme concentration corresponding to a 36 µg/L of milk of W. coagulans, 50 IMCU/L of camel chymosin, holding time of 4 h, and incubation temperature of 60 °C provided the optimal textural hardness for both camel and bovine milk cheeses. Seven treatments were analyzed in experiment (2) were analyzed for physicochemical properties, yield, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGEitation). The results showed that pure Withania extract exhibited the lower coagulating effect resulting in cheeses with low yield, hardness, fat, protein, and total solids. The SDS-PAGE electropherograms of camel cheese showed several low molecular weight bands as compared to bovine cheese. This phenomenon is due to excessive proteolysis in camel cheese, which we believed is caused by the presence of endogenous enzymes.

Figure 1

Interaction effects of four independent variables on the yield of camel and bovine milk cheeses: camel chymosin (IMCU/1000 mL milk), Withania extract (µg protein/1000 mL milk), Incubation time (hours), and Incubation temperature (°C) (Experiment 1).

Figure 2

Interaction effects of four independent variables on the hardness of camel and bovine milk cheeses: camel chymosin (IMCU/1000 mL milk), Withania extract (µg protein/1000 mL milk), Incubation time (hours), and Incubation temperature (°C) (Experiment 1).

Figure 3

Correlations between (a) camel and bovine cheese yield (%), (b) camel and bovine cheese hardness (g), and (c) cheese yield and cheese hardness for camel (red) and bovine (blue) cheeses. All correlations are significant (p < 0.001). The experimental design is presented in Table 1 (Experiment 1).

Figure 4

Correlations between (a) cheese yield and cheese hardness and between (b) cheese yield and cheese total solids for camel (red) and bovine (blue) cheeses. Correlations excluding pure Withania treatments are significant for both camel and bovine cheeses (p < 0.001). The codes are shown in Table 2 (Experiment 2).

Figure 5

Correlations for camel (red) and bovine (blue) cheeses between (a) lightness and yellowness (CM cheeses are lighter in color and less yellow than BM cheeses; p < 0.001) and between (b) acidity and pH (CM cheeses have higher acidity and lower pH than BM cheeses; p < 0.001). All correlations are significant (p < 0.001). Chymosin yields cheeses that are less yellow, lighter in color, less acidic, and with higher pH than those yielded with Withania treatment (p < 0.001). The codes are presented in Table 2 (Experiment 2).

Figure 6

Fourier-transform infrared spectra of camel and bovine milk cheeses treated with pure Withania extract or chymosin (Experiment 2).

Figure 7

Sodium dodecyl sulfate–polyacrylamide gel electrophoresis of camel and bovine cheeses, wheys, and milk (Experiment 2).