Bioactive peptides in ripened cheeses: release during technological processes and resistance to the gastrointestinal tract

Comprehensive review of extraction, purification, structural characteristics, pharmacological activities, structure-activity relationship and application of seabuckthorn protein and peptides

Seabuckthorn (Hippophae rhamnoides) is an excellent plant that has the concomitant function of both medicine and foodstuff with high nutritional and health-promoting properties. As a pivotal bioactive component mainly existing in the seeds and leaves, seabuckthorn protein and its derived peptides have aroused wide attention owing to their multifaceted pharmacological activities, including anti-hypertensive, hypoglycemic, anti-obesity, anti-freeze, immunomodulatory, anti-inflammatory, sobriety, anti-oxidant and anti-neurodegenerative functions. Despite these promising attributes, the application of seabuckthorn peptides as functional food and medicines are impeded due to lack of a comprehensive understanding of pharmacological activities and intricate structure-activity relationship. Therefore, this review systematically summarizes the latest advancements in the extraction, purification, structural characteristics, pharmacological activities, digestion, absorption and transport, and application of seabuckthorn protein or peptides. Noteworthily, the structure-activity relationship is specifically delved into the hypoglycemic, anti-hypertensive, anti-obesity, anti-neurodegenerative and anti-oxidant peptides. Moreover, the shortcomings of current research and promising prospects are also highlighted. This comprehensive overview will provide a framework for future exploration and application of seabuckthorn protein or peptides in the realms of food and pharmaceuticals, offering a promising horizon for health benefits.

Peptide Profile Changes in Buffalo Milk Cheese during Different Storage Periods and Characterization of Novel Bioactive Peptides through Peptidomics

This study aimed to investigate the changes in the bioactive peptides (BPs) of buffalo milk cheese (BMC) within 15 days of storage. A total of 3605 peptides were identified in the BMC, with 260 peptides remaining stable for 15 days. Among these, the peak intensities of all reported BPs (9 peptides) increased on the 15th day. Additionally, two novel antioxidant peptides, AYF (IC50 = 160.5 μM) and YPFPGPIPK (IC50 = 108.6 μM), and two novel angiotensin-converting enzyme (ACE) inhibitory peptides, LRF (IC50 = 214.9 μM) and APFPEVFGK (IC50 = 880.0 μM), were identified. The molecular docking results implied that the active sites on ECH-associated protein 1 (Arg 415, Arg 483, Arg 380, and Asn 382) and the active sites in the three active pockets of ACE (S1, S2, and S'1) are crucial for peptide activity. This study demonstrates that BMC is a stable resource of BPs and has the potential to be used in functional foods.

A Comparative Study of the Stability, Transport, and Structure-Activity Relationship of Round Scad Derived Peptides with Antineuroinflammatory Ability

Our previous study identified round scad neuroprotective peptides with different characteristics. However, the intrinsic relationship between their structure and bioactivity, as well as their bioavailability, remains unclear. The aim of this study is to elucidate the bioavailability of these peptides and their structure-activity relationship against neuroinflammation. Results showed that the SR and WCP peptides were resistant to gastrointestinal digestion. Additionally, peptides SR, WCP, and WCPF could transport Caco-2 monolayers as intact peptides. The permeability coefficients (Papp) of SR, WCP, and WCPF in Caco-2 monolayer were (1.53 ± 0.01) × 10-5, (2.12 ± 0.01) × 10-5, and (8.86 ± 0.03) × 10-7 cm/s, respectively. Peptides SR, WCP, and WCPF, as promising inhibitors of JAK2 and STAT3, could attenuate the levels of pro-inflammatory cytokines and regulate the NFκB and JAK2/STAT3 signaling pathway in LPS-treated BV-2 cells. WCPF exerted the highest anti-inflammatory activity. Moreover, bioinformatics, molecular docking, and quantum chemistry studies indicated that the bioactivity of SR was attributed to Arg, whereas those of WCP and WCPF were attributed to Trp. This study supports the application of round-scad peptides and deepens the understanding of the structure-activity relationship of neuroprotective peptides.

Probiotic Potential and Application of Indigenous Non-Starter Lactic Acid Bacteria in Ripened Short-Aged Cheese

There are massive sources of lactic acid bacteria (LAB) in traditional dairy products. Some of these indigenous strains could be novel probiotics with applications in human health and supply the growing needs of the probiotic industry. In this work, were analyzed the probiotic and technological properties of three Lactobacilli strains isolated from traditional Brazilian cheeses. In vitro tests showed that the three strains are safe and have probiotic features. They presented antimicrobial activity against pathogenic bacteria, auto-aggregation values around 60%, high biofilm formation properties, and a survivor of more than 65% to simulated acid conditions and more than 100% to bile salts. The three strains were used as adjunct cultures separately in a pilot-scale production of Prato cheese. After 45 days of ripening, the lactobacilli counts in the cheeses were close to 8 Log CFU/g, and was observed a reduction in the lactococci counts (around -3 Log CFU/g) in a strain-dependent manner. Cheese primary and secondary proteolysis were unaffected by the probiotic candidates during the ripening, and the strains showed no lipolytic effect, as no changes in the fatty acid profile of cheeses were observed. Thus, our findings suggest that the three strains evaluated have probiotic properties and have potential as adjunct non-starter lactic acid bacteria (NSLAB) to improve the quality and functionality of short-aged cheeses.

How starter cultures affect the peptidomic profile and bioactive activities of the Asiago-PDO cheese throughout ripening

Our study investigated the chemical, microbiological, and bioactive peptide profiles of Asiago Protected Designation of Origin (PDO) cheese from two dairies (Dairy I and II) produced over two consecutive days (batches) and analysed during three months of ripening. The effect of different starter cultures was evaluated. The microbiome varied between the dairies and batches, with curds post-salting dominated by the starter culture-associated genera. During ripening, there was an increasing trend in the Lactobacillus genus, especially for Dairy I, which used an industrial starter. Bioactive peptide intensities differed throughout ripening due to the extent of proteolysis, and their intensity or concentration evolved, modifying, and differentiating profiles. The industrial starter used in Dairy I had the highest relative intensity (average value 76.50%) of bioactive peptides after three months of ripening. In contrast, the cheeses made with natural milk starter (Dairy II) had lower total relative intensity (average value 47.75%) but produced ACE-inhibitory peptides through sub-dominant strains and non-starter lactic acid bacteria. The importance of autochthonous strains of each micro-region even within a delimited PDO production area was highlighted.

Identification of Immune-Active Peptides in Casein Hydrolysates and Its Transport Mechanism on a Caco-2 Monolayer

In this study, we investigated the transport mechanism of immune-active peptide fragments isolated from casein gastrointestinal hydrolysates via a Caco-2 monolayer. The casein gastrointestinal hydrolysates could stimulate B-lymphocyte proliferation and reduce the TNF-α level. Then, we identified the bioactive peptide fragments derived from casein gastrointestinal hydrolysis using LC-MS/MS. Our results demonstrated that the transport mechanism of five immune-active peptides at the cell level was bypass transport. In addition, the majority of peptide RYPLGYL was transported through the monolayer cell membrane as an intact form for playing immune-active functions. The KHPIK and FFSDK were mainly degraded into small fragments, except for a small amount passing through Caco-2 cells in an entire form. Overall, these results suggested that casein or its immune-active peptides might play a role in regulation of the intestinal immune system.

Peptidomics Profile, Bioactive Peptides Identification and Biological Activities of Six Different Cheese Varieties

Several recent published studies reported that cheese consumption may protect against the onset of cardiovascular diseases and type-2 diabetes due to the presence of bioactive peptides. In the present work, six cheese varieties (the Egyptian traditional cheeses Karish, Domiati and Ras as well as Feta-type, Gouda and Edam cheeses) were characterized for their peptidomics profiles with high-resolution mass spectrometry, biological activities and content in bioactive peptides. The highest ACE-inhibitory and DPP-IV-inhibitory activities were found in Gouda cheese, which also displayed the highest antioxidant activity. A total of 809 peptides originating from the major milk proteins were identified, and 82 of them were bioactive. Most of them showed ACE-inhibitory, antioxidant and DPP-IV-inhibitory activities. The highest amount of the in vivo anti-hypertensive tripeptides VPP and IPP was found in Gouda cheese (39.19 ± 1.26 and 17.72 ± 0.89 mg/100 g of cheese, respectively), whereas the highest amount of APFPE was detected in Edam cheese (509.13 ± 20.44 mg/100 g of cheese). These results suggest that the intake of Edam, Domiati and, especially, Gouda cheeses may result in a possible anti-hypertensive effect in hypertensive subjects.

The identification of antioxidant and ACE-I peptides in different turkish ripened cheeses

The principal purpose of this study was to determine antioxidant and ACE-inhibitory (angiotensin converting enzyme) activities of 5 ripened Turkish cheese varieties (Kashar, Erzincan Tulum, Izmir Tulum Gruyere, Mihalic). Among the water-soluble extracts with a molecular weight smaller than 3 kDa Gruyere and Erzincan Tulum exhibited the highest free radical scavenger activity in FRAP (Ferric Reducing Ability of Plasma) and ABTS [2,20-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid)] assays, respectively. For the inhibition of ACE, Mihalic was more effective than others. The water-soluble extracts of five cheese were analyzed with liquid chromatography-tandem mass spectrometry to identify the peptide sequences. Totally 394 peptides were sequenced; of these, 134 from αs1-casein, 44 from αs2-casein, 198 from β-casein, and 18 from κ-casein. Among these sequences, 48 peptides were reported as bioactive with the activities including ACE-inhibitory, antioxidant, antimicrobial, DPP-IV inhibitory, antidiabetic, immunomodulating, antithrombotic, anti-inflammatory, and inhibition of cholesterol solubility. These results showed that Turkish cheeses are good sources of bioactive peptides.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13197-022-05414-3.

Cardioprotective Peptides from Milk Processing and Dairy Products: From Bioactivity to Final Products including Commercialization and Legislation

Recent research has revealed the potential of peptides derived from dairy products preventing cardiovascular disorders, one of the main causes of death worldwide. This review provides an overview of the main cardioprotective effects (assayed in vitro, in vivo, and ex vivo) of bioactive peptides derived from different dairy processing methods (fermentation and enzymatic hydrolysis) and dairy products (yogurt, cheese, and kefir), as well as the beneficial or detrimental effects of the process of gastrointestinal digestion following oral consumption on the biological activities of dairy-derived peptides. The main literature available on the structure–function relationship of dairy bioactive peptides, such as molecular docking and quantitative structure–activity relationships, and their allergenicity and toxicity will also be covered together with the main legislative frameworks governing the commercialization of these compounds. The current products and companies currently commercializing their products as a source of bioactive peptides will also be summarized, emphasizing the main challenges and opportunities for the industrial exploitation of dairy bioactive peptides in the market of functional food and nutraceuticals.

Low-fat akawi cheese made from bovine-camel milk blends: Rheological properties and microstructural characteristics

Camel milk (CM) can be used as an ingredient to produce various dairy products but it forms weak rennet-induced and acid-induced gels compared with bovine milk (BM). Therefore, in this study, we aimed to investigate the effect of blending bovine milk with camel milk on the physicochemical, rheological (amplitude sweep and frequency sweep), and microstructural properties of low-fat akawi (LFA) cheese. The cheeses were made of BM only or BM blended with 15% (CM15%) or 30% (CM30%) camel milk and stored at 4°C for 28 d. The viscoelastic properties as a function of temperature were assessed. The LFA cheeses made from blended milks had higher moisture, total Ca, and soluble Ca contents, and had higher pH 4.6-water-soluble nitrogen compared with those made from BM. Analysis by scanning electron microscopy demonstrated that the microstructures formed in BM cheese were rough with granular surfaces, whereas those in blended milk cheeses had smooth surfaces. Hardness was lower for LFA cheeses made from blended milk than for those made from BM only. The LFA cheeses demonstrated viscoelastic behavior in a linear viscoelastic range from 0.1 to 1.0% strain. The storage modulus (G') was lower in LFA cheese made from BM over a range of frequencies. Adding CM reduced the resistance of LFA cheeses to flow as temperature increased. Blended cheeses exhibited lower complex viscosity values than BM cheeses during temperature increases. Thus, the addition of camel milk improved the rheological properties of LFA cheese.

Milk-clotting and hydrolytic activities of an aspartic protease from Salpichroa origanifolia fruits on individual caseins

In recent years, many attempts have been made to find new plant proteases to make artisan cheeses. The global increase in cheese consumption, together with a lower supply and increasing cost of calf rennet, religious factors (Islam and Judaism) and food choices (vegetarianism) have led to the search for suitable rennet substitutes for milk clotting. This study describes the milk-clotting and hydrolytic activities of an aspartic protease from Salpichroa origanifolia fruits (SoAP) on individual caseins to explore its potential use as an alternative to animal rennet. The milk-clotting index obtained for SoAP was 8.4 times lower than that obtained for chymosin. SoAP showed a higher degree of hydrolysis on α-casein than on the other fractions under the proposed conditions. RP-HPLC, mass spectrometry analyses and sequencing of the hydrolysates allowed identifying five peptides from α-casein, one peptide from β-casein, and three peptides from k-casein. In silico analysis showed that the peptides identified may display a wide variety of potential biological activities. These results demonstrate the possibility of using SoAP for the manufacture of new types or artisan cheeses, with the simultaneous added value of the potential health-promoting benefits of the bioactive peptides generated during the hydrolysis.

Bioactive peptide release and the absorption tracking of casein in the gastrointestinal digestion of rats

Bovine casein is considered as an important source of many bioactive peptides (BAPs), which can also be produced via in vitro simulated gastrointestinal hydrolysis. To perform their physiological functions, some active peptides need to pass through the intestinal epithelial barrier and keep their structural integrity after oral administration. Owing to the complexity of in vivo digestion and absorption, there have been few studies in this area. In this study, casein was labeled with FITC to trace its digestion and absorption in Sprague Dawley (SD) rats. Gastric juice, intestinal fluid, blood, and intestinal tissue samples were collected at different time-points for preservation and analysis after intragastric administration. The results showed that CN-FITC exhibited good labeling stability in the gastrointestinal digestive juice both in vivo and in vitro, suggesting its potential to be used for the detection and tracking of casein hydrolysate. After the intra-gastric administration of FITC, the diffusion rates of fluorescent substances in serum were much higher than in the CN-FITC group. The maximum peptide content in the CN-FITC group during intestinal digestion was achieved 2 h after administration, and electrophoretic analysis of the hydrolysate composition suggested that the molecular weights of the peptides were mainly concentrated in the range of 3.4-10 kDa. The hydrolyzed peptides from CN-FITC could be absorbed into the blood just 1 h after administration. Frozen sections of rat duodenal tissue were observed under a confocal laser scanning microscope, and they showed that the CN-FITC digested products were absorbed from villi to mucosa in the rat intestines, and the casein-hydrolyzed polypeptides were accumulated significantly in tissue samples 2 h after administration. The peptides were mainly absorbed in the duodenum on the basis of absorption experiments using an everted gut sac. After intestinal digestion for 2 h, peptides with weights less than 5 kDa were enriched and identified using LC-MS-MS, and they were found to be mainly derived from β-casein, containing potential angiotensin-I-converting enzyme inhibitory, antioxidant, dipeptidyl peptidase IV inhibitory, and morphine-like peptides. The peptides from casein hydrolysate were tracked entering the blood through the intestinal epithelial barrier in the form of complete fragments, and they might exert potential physiological activity in vivo.

Current Trends of Enterococci in Dairy Products: A Comprehensive Review of Their Multiple Roles

As a genus that has evolved for resistance against adverse environmental factors and that readily exchanges genetic elements, enterococci are well adapted to the cheese environment and may reach high numbers in artisanal cheeses. Their metabolites impact cheese flavor, texture, and rheological properties, thus contributing to the development of its typical sensorial properties. Due to their antimicrobial activity, enterococci modulate the cheese microbiota, stimulate autolysis of other lactic acid bacteria (LAB), control pathogens and deterioration microorganisms, and may offer beneficial effects to the health of their hosts. They could in principle be employed as adjunct/protective/probiotic cultures; however, due to their propensity to acquire genetic determinants of virulence and antibiotic resistance, together with the opportunistic character of some of its members, this genus does not possess Qualified Presumption of Safety (QPS) status. It is, however, noteworthy that some putative virulence factors described in foodborne enterococci may simply reflect adaptation to the food environment and to the human host as commensal. Further research is needed to help distinguish friend from foe among enterococci, eventually enabling exploitation of the beneficial aspects of specific cheese-associated strains. This review aims at discussing both beneficial and deleterious roles played by enterococci in artisanal cheeses, while highlighting the need for further research on such a remarkably hardy genus.