Antioxidant Peptides from Goat Milk Fermented by Lactobacillus casei L61: Preparation, Optimization, and Stability Evaluation in Simulated Gastrointestinal Fluid

Abstract

Antioxidant peptides are currently the focus of many studies, since they eliminate free radicals in the human body without harmful effects. In the present study, Lactobacillus casei L61 was used as a starter culture to ferment goat milk because of its high capacity to produce antioxidant peptides. An optimal nutrients formula (casein, casein peptone, glucose, soybean peptone, inulin, calcium lactate, and cysteine) was investigated by Plackett–Burman (P–B) and Box–Behnken (B–B) designs for response surface methodology (RSM). Antioxidant peptides were successively isolated and purified from the fermented goat milk. Furthermore, the stability of the antioxidant peptides was evaluated in a simulated gastrointestinal tract at 37 °C. The results showed that calcium lactate, glucose, and casein peptone significantly affected the antioxidant activity of goat milk. The optimal additive amounts were 0.99% (w/v) calcium lactate, 0.21% (w/v) glucose, and 0.29% (w/v) casein peptone. The hydroxyl free radical scavenging rate increased significantly (p < 0.001) from 56.50 ± 0.57% to 88.01 ± 0.69%; the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rate increased up to 63.48 ± 1.22% under the optimal conditions (n = 3). Our research provides a fitted mathematical model for antioxidant peptides production. Besides, these antioxidant peptides had great stability during simulated gastrointestinal digestion.

Antioxidant activities, proteolytic activity and growth behavior of Lactobacillus cultures during fermentation of goat milk

“…M8 had exhibited highest hydroxyl free radical scavenging activity (53.43%), followed by M9 (50.98%), NK9 (48.88%), M3 (46.93%) and M11 (35.32%) after 48 h at 37ºC. It was observed that the percentage of hydroxyl free radical was increased with an increase in the incubation time from 0 to 48 h. Similar kind of observation was shown by Shu et al (2018) reported hydroxyl free radical scavenging activity in goat milk fermented by Lactobacillus casei L61 and added the optimal additive amounts were 0.99% (w/v) calcium lactate, 0.21% (w/v) glucose, and 0.29% (w/v) casein peptone. They found that the hydroxyl free radical scavenging rate increased significantly (p < 0.001) from 56.50 ± 0.57% to 88.01 ± 0.69%.…”

Hypolipidemic Roles of Casein-Derived Peptides by Regulation of Trans-Intestinal Cholesterol Excretion and Bile Acid Synthesis

“…Peptide 12 is present in casein hydrolysates known to have antioxidant, anti-hypertension, and osteoblast proliferation/differentiation effects [ 38 , 39 , 40 ]. Although the antioxidant effect is commonly observed, other peptides listed in the table (peptides 1 and 5) are also present in antioxidant casein hydrolysates, indicating that their molecular mechanisms need to be revealed [ 41 , 42 ]. A recent review explained that bioactive peptides can function in the lumen of small intestine levels and be transported into the bloodstream through microfold cells, exosomes, and enterocytes [ 43 ].…”

The Effect of Eight Thermal Protectants on the Survival Rate and the Viable Counts of Lactobacillus casei After Heat Treatment in Fermented Goat Milk

“…In the previous work, four strains with good antioxidant capacity and DPPH clearance rate have been screened, among which the most heat resistant is L.casei L61 (Chen et al, 2012). The optimal nutritional formula for antioxidant peptide production by Lactobacillus casei have been explored (Shu et al, 2018). In this study, the effects of eight thermal protectants (skim milk, sucrose, glucose, β-cyclodextrin, gelatin, maltodextrin, glycerol, trehalose) on the heat resistance of Lactobacillus casei L61 in fermented goat milk were investigated by single factor experiments.…”