Milk Fermentation by Lacticaseibacillus rhamnosus GG and Streptococcus thermophilus SY-102: Proteolytic Profile and ACE-Inhibitory Activity

Advances in characterization of probiotics and challenges in industrial application

An unbalanced diet and poor lifestyle are common reasons for numerous health complications in humans. Probiotics are known to provide substantial benefits to human health by producing several bioactive compounds, vitamins, short-chain fatty acids and short peptides. Diets that contain probiotics are limited to curd, yoghurt, kefir, kimchi, etc. However, exploring the identification of more potential probiotics and enhancing their commercial application to improve the nutritional quality would be a significant step to utilizing the maximum benefits. The complex evolution patterns among the probiotics are the hurdles in their characterization and adequate application in the industries and dairy products. This article has mainly discussed the molecular methods of characterization that are based on the analysis of ribosomal RNA, whole genome, and protein markers and profiles. It also has critically emphasized the emerging challenges in industrial applications of probiotics.

Blackberry Juice Fermented with Two Consortia of Lactic Acid Bacteria and Isolated Whey: Physicochemical and Antioxidant Properties during Storage

Fermenting fruit juices with lactic acid bacteria (LAB) is a sustainable method to enhance fruit harvests and extend shelf life. This study focused on blackberries, rich in antioxidants with proven health benefits. In this research, we examined the effects of fermentation (48 h at 37 °C) at 28 days on whey-supplemented (WH, 1:1) blackberry juice (BJ) inoculated with two LAB mixtures. Consortium 1 (BJWH/C1) included Levilactobacillus brevis, Lactiplantibacillus plantarum, and Pediococcus acidilactici, while consortium 2 (BJWH/C2) comprised Lacticaseibacillus casei and Lacticaseibacillus rhamnosus. All of the strains were previously isolated from aguamiel, pulque, and fermented milk. Throughout fermentation and storage, several parameters were evaluated, including pH, lactic acid production, viscosity, stability, reducing sugars, color, total phenolic content, anthocyanins, and antioxidant capacity. Both consortia showed a significant increase in LAB count (29-38%) after 16 h. Sample BJWH/C2 demonstrated the best kinetic characteristics, with high regression coefficients (R2 = 0.97), indicating a strong relationship between lactic acid, pH, and fermentation/storage time. Despite some fluctuations during storage, the minimum LAB count remained at 9.8 log CFU/mL, and lactic acid content increased by 95%, with good storage stability. Notably, sample BJWH/C2 increased the total phenolic content during storage. These findings suggest that adding whey enhances biomass and preserves physicochemical properties during storage.

Harnessing the Power of a Novel Triple Chelate Complex in Fermented Probiotic Dairy Products: A Promising Solution for Combating Iron Deficiency Anemia

This study discovered and examined novel triple chelate complexes involving iron, ascorbic acid, and essential amino acids (AsA-Fe-AmA triple chelate complexes) for the first time. The mechanism of complex formation was studied using FTIR spectroscopy and quantum chemical modeling. The produced complexes were shown to be suitable for fortifying food items with a pH of 3-7 that have not been exposed to heat treatment at temperatures over 75 °C for more than 15 min. Thus, it can be said that the concentration for milk fortification should be 0.005 mol/L or less. In vivo experiments in rats models revealed that the synthesized complexes increased serum iron levels after a single application to reference values within 24 h of oral administration. The iron level increased by 14.0 mmol/L at 2 mL dose of the complex. This fact makes it possible to consider the use of developed complexes and developed fermented dairy products for the prevention of iron deficiency and iron deficiency anemia. Research on the effect of discovered compounds on the physicochemical and organoleptic qualities of milk was conducted. Furthermore, iron ascorbate threoninate, iron ascorbate methioninate, iron ascorbate lysinate, and iron ascorbate tryptophanate all had a beneficial effect on Lacticaseibacillus rhamnosus at concentrations as low as 0.0005 mol/L, which is significant for milk fermentation. A study of fermented milk products revealed that the most effective AsA-Fe-AmA triple chelate complex is iron ascorbate lysinate, which might be further investigated as a viable molecule for dietary fortification in iron deficiency anemia. It was found that fortified fermented milk products had a titratable acidity of 67 ± 1°T, pH of 4.38 ± 0.05, and a viscosity of 2018 ± 142 Pa·s.

Screening and molecular dynamics simulation of ACE inhibitory tripeptides derived from milk fermented with Lactobacillus delbrueckii QS306

Peptides in milk fermented with Lactobacillus delbrueckii QS306 before and after ultrahigh pressure treatment were identified using proteomics. Subsequently, 16 stable tripeptides were screened out based on activity score prediction, PeptideCutter analysis, and hydrophobicity calculations. Among them, WRP, WSR, and YRP showed the best angiotensin-converting enzyme (ACE) inhibitory activity, and their semi-inhibitory concentrations were 46.707, 300.121, and 89.555 μM, respectively. WRP and WSR were competitive inhibitors, whereas YRP was non-competitive. Gastrointestinal simulation revealed that WRP and YRP had better gastrointestinal stability. The values of RMSD, ΔGbind, ΔGpol, and RSMF obtained from molecular dynamics simulation indicated that the interaction of WRP and ACE was stable. Thus, Lactobacillus delbrueckii QS306-fermented milk can serve as an important source of ACE inhibitory peptides both before and after ultrahigh pressure treatment. The strategy of in silico screening, activity evaluation, and molecular dynamics simulation adopted in this study can be applied to the large-scale screening of novel peptides with high ACE inhibitory activity.

Purine nucleosidase (PNase) activity, probiotics potential, and food applicability of a newly-isolated Levilactobacillus brevis LAB42

Hyperuricemia, a condition characterized by elevated levels of uric acid in the blood, is known as a risk factor for gout disease. In this study, we isolated a total of 72 MRS-grown colonies and evaluated their purine nucleosidase (PNase) activity. Among the isolated bacteria, Levilactobacillus (L.) brevis LAB42 displayed the highest PNase activity. Our findings also indicate that PNase activity can vary among lactic acid bacterial strains and during different growth phases. Based on the kinetics study, LAB42 consistently exhibits the highest PNase activity. Due to its ability to attach to Caco-2 cells and its resistance to acidic environments and bile exposure, L. brevis LAB42 was chosen for further studies and showed that with the right combination of additives, it has the potential to be an appropriate starter for milk fermentation.

Exploring novel ANGICon-EIPs through ameliorated peptidomics techniques: Can deep learning strategies as a core breakthrough in peptide structure and function prediction?

Dairy-derived angiotensin-I-converting enzyme inhibitory peptides (ANGICon-EIPs) have been regarded as a relatively safe supplementary diet-therapy strategy for individuals with hypertension, and short-chain peptides may have more relevant antihypertensive benefits due to their direct intestinal absorption. Our previous explorations have confirmed that endogenous goat milk short-chain peptides are also an essential source of ANGICon-EIPs. Nonetheless, there are limited explorations on endogenous ANGICon-EIPs owing to the limitations of the extraction and enrichment of endogenous peptides, currently. This review outlined ameliorated pre-treatment strategies, data acquisition methods, and tools for the prediction of peptide structure and function, aiming to provide creative ideas for discovering novel ANGICon-EIPs. Currently, deep learning-based peptide structure and function prediction algorithms have achieved significant advancements. The convolutional neural network (CNN) and peptide sequence-based multi-label deep learning approach for determining the multi-functionalities of bioactive peptides (MLBP) can predict multiple peptide functions with absolute true value and accuracy of 0.699 and 0.708, respectively. Utilizing peptide sequence input, torsion angles, and inter-residue distance to train neural networks, APPTEST predicted the average backbone root mean square deviation (RMSD) value of peptide (5-40 aa) structures as low as 1.96 Å. Overall, with the exploration of more neural network architectures, deep learning could be considered a critical research tool to reduce the cost and improve the efficiency of identifying novel endogenous ANGICon-EIPs.

ACE-Inhibitory Activity of Whey Proteins Fractions Derived of Fermentation by Lacticaseibacillus rhamnosus GG and Streptococcus thermophilus SY-102

Many studies have reported the benefits of probiotic microorganisms and the production of angiotensin-converting enzyme (ACE) inhibitors. Determining the proteolytic and ACE inhibition capacities during whey fermentation was the goal of the study. Lacticaseibacillus rhamnosus GG, Streptococcus thermophilus SY-102, and both bacteria together were initially inoculated into whey, reaching an initial concentration of 10⁸ CFU per milliliter in each fermentation system. Through the use of TNBS, SDS-PAGE, and SEC-HPLC methods, the proteolytic profile was examined. An in vitro investigation was performed to test the ACE inhibition capacity. With S. thermophilus, the logarithmic phase of microbial development was shorter than with L. rhamnosus (6 and 12 h, respectively). The logarithmic phase in the co-culture fermentation, however, was extended to 24 h. There were no significant differences in pH between the fermentations. However, the co-culture had a greater concentration of protein hydrolysis (453 ± 0.06 μg/mL), as indicated by the amount of free amino groups. Similarly, this fermentation produced more low molecular weight peptides. The higher inhibition activity, which increased at the conclusion of the fermentation with the co-culture and reached 53.42%, was influenced by the higher peptide synthesis. These findings highlighted the significance of creating useful co-culture products.

Bioactive peptides of whey: obtaining, activity, mechanism of action, and further applications

Bioactive peptides derived from diverse food proteins have been part of diverse investigations. Whey is a rich source of proteins and components related to biological activity. It is known that proteins have effects that promote health benefits. Peptides derived from whey proteins are currently widely studied. These bioactive peptides are amino acid sequences that are encrypted within the first structure of proteins, which required hydrolysis for their release. The hydrolysis could be through in vitro or in vivo enzymatic digestion and using microorganisms in fermented systems. The biological activities associated with bio-peptides include immunomodulatory properties, antibacterial, antihypertensive, antioxidant and opioid, etc. These functions are related to general conditions of health or reduced risk of certain chronic illnesses. To determine the suitability of these peptides/ingredients for applications in food technology, clinical studies are required to evaluate their bioavailability, health claims, and safety of them. This review aimed to describe the biological importance of whey proteins according to the incidence in human health, their role as bioactive peptides source, describing methods, and obtaining technics. In addition, the paper exposes biochemical mechanisms during the activity exerted by biopeptides of whey, and their application trends.