In vitro antioxidant and angiotensin-converting enzyme inhibitory activity of fermented milk with different culture combinations

Abstract

This study investigated the effects of Lactobacillus plantarum (Lp) and Bifidobacterium animalis ssp. lactis (Ba) in co-cultures with Streptococcus thermophilus (St) on changes in the acidification profile, proteolytic activity, peptide production, in vitro antioxidant activity, and angiotensin-converting enzyme (ACE) inhibitory properties of fermented milks during 21 d of storage at 4°C. The pH values and proteolysis in all batches showed a gradual decrease and increase during storage, respectively. The ACE-inhibitory activity and total antioxidant capacity of all co-fermented milk samples followed a similar pattern, with maximum values on d 6 of storage. The St starter, in conjunction with Ba or Lp or both, enhanced proteolysis, peptide generation, and ACE-inhibitory and antioxidant activity, but decreased pH values compared with St alone. The St-Ba-Lp samples showed higher DPPH • (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity, hydroxyl radical scavenging activity, and total antioxidant capacity, but similar superoxide anion scavenging activity compared to St-Ba or St-Lp samples. The St-Ba samples showed higher DPPH • radical scavenging activity but lower hydroxyl radical scavenging activity than St-Lp samples. In the ACE-inhibitory assays, the St-Lp samples exhibited relatively low activity among the co-fermented milks, digested or not. The presence of Ba and Lp in fermentation together did not affect ACE-inhibitory activity in undigested fermented milks compared with the presence of Ba alone, and St-Ba-Lp fermented milks demonstrated an increase in ACEinhibitory activity after simulated gastrointestinal digestion in storage. Pepsin digestion largely improved ACE-inhibitory activity, except in St-Lp samples, in which the activity was reduced. Further hydrolysis by trypsin reduced final activity in digestion. This study suggests that co-cultured fermentation with probiotics improves in vitro antioxidant and ACE inhibition activity in fermented milks, and this effect is partly due to the higher proteolytic activity of probiotics.

Study on extraction methods of polysaccharides from a processed product of Aconitum carmichaeli Debx.

“…DPPH and ABTS radicals were widely used to evaluate the antioxidant ability of polysaccharides. 22,28,29 As shown in Fig. 4A, the scavenging activity of crude polysaccharides DAE-PTXP, As shown in Fig.…”

Proteomic characterization of kefir milk by two‐dimensional electrophoresis followed by mass spectrometry

“…25 Furthermore, it is known that the peptides and amino acid released by the proteolytic processes can positively influence the nutritional characteristics of the final product. 26 The κ-casein polypeptides corresponding to the spots KA, KB, and KC contain the sequence YIPIQYVLSR that correspond to the casoxin C, a bioactive compound that acts mainly as an opioid antagonist and is obtained from the digestion of κ-casein. In particular, this peptide has shown its activity against the suppressive effect of DAGO, a μ-opioid agonist evoking the contraction of ileum with rapid and slow components.…”

“…Several authors have found that the proteolytic enzymes released from LAB are active during the fermentation process and in the fermented dairy products 24 and also that the choice of the starter culture can influence the proteolysis characteristics 25 . Furthermore, it is known that the peptides and amino acid released by the proteolytic processes can positively influence the nutritional characteristics of the final product 26 …”

Probiotics in the dairy industry—Advances and opportunities

“…A study investigating the effect of L. plantarum and B. animalis subsp. lactis in co‐cultures with S. thermophilus on different functional characteristics of fermented milk reported significantly higher DPPH radical scavenging activity, hydroxyl radical scavenging activity, and total antioxidant activity in milk compared to the milk fermented by only S. thermophilus (Li, Tang, et al., 2020; Li, Wu, et al., 2020). Skimmed milk fermented by L. plantarum WW has been shown to regulate lipid metabolism and cholesterols levels in rats fed a high‐fat diet (Li, Tang, et al., 2020; Li, Wu, et al., 2020).…”