An ultrasound, a non-thermal technique, can be employed to increase a probiotic’s biomass and its fermentation products. The effects of high-intensity ultrasounds (20%, 30%, and 40% amplitudes for 3 min) on the growth and fermentative profile of Lactobacillus acidophilus and helveticus were studied. The use of an ultrasound decreased the Lag phase and increased the maximum growth potential; however, the effect depended on the amplitude used. For both probiotics, the β-galactosidase activity increased in the treatments with a 20% amplitude—3 min and 30% amplitude—but decreased in the treatment with a 40% amplitude—3 min in comparison to the values found in the control treatment. The two probiotics showed a decrease in the protein concentration when compared with the control treatment. Both probiotics presented the lowest values of proteolysis in the treatments with a 30% amplitude—3 min. Lactic, acetic, and citric acids were the organic acids that were present in the highest concentration and formic acid was not detected in either of the two probiotics. It can be concluded that the ultrasound amplitude has a noticeable influence on the growth and fermentation profiles of both probiotics. The results from this study could be used in subsequences investigations to enhance the postbiotic production of Lactobacillus acidophilus and Lactobacillus helveticus.

Requeson cheese is obtained from whey proteins. The production of this cheese is the most economical way to recover and concentrate whey proteins, which is why it is frequently made in some Latin American countries. Four requeson cheese treatments were prepared with different concentrations and combinations of salts (sodium chloride and/or potassium chloride) and were conventionally or vacuum packed. Proteolysis, peptide concentration, angiotensin-converting enzyme (ACE) inhibitory and antioxidant (DPPH and ABTS) activities were evaluated over time (one, seven and fourteen days). Requeson cheese presented antioxidant and ACE inhibitory activities, however, these values vary depending on salt addition, type of packaging and time of storage. The highest values of antioxidant activity (ABTS) were found in cheese added with 1.5% NaCl and 1.5% (NaCl/KCl, 1:1). Cheese without added salt and vacuum packed presented the highest ACE inhibition percentage at day seven. Therefore, it can be concluded that requeson cheese elaborated exclusively of sweet whey, presents antioxidant and ACE inhibition activity. However, for a cheese with ACE inhibitory capacity, it is recommended not to add salts or add at 1% (NaCl) and vacuum pack it. Additionally, for a cheese with antioxidant activity, it is recommended to add salt at 1.5% either NaCl or (1:1) NaCl/KCl and pack it either in a polyethylene bag or vacuum. In conclusion, requeson cheese elaborate with 100% sweet whey is a dairy product with antioxidant and ACE inhibition activity, being low in salt and fat.

Ferulic acid is an antimicrobial and antioxidant phenolic compound located in the cell walls of plants and therefore classified as a natural antioxidant. The objective of this study was to assess the antimicrobial and antioxidant potential of ferulic acid as a substitute for nitrites in the elaboration of dried meat. Four treatments were evaluated: dried meat without nitrites or ferulic acid, (control treatment), dried meat with nitrites, dried meat with 0.05% of ferulic acid, and dried meat with 0.1% of ferulic acid. The antioxidant activity, lipid oxidation, and microbiological quality were evaluated throughout the dried meat shelf life. The protein, fat, and ash content was not different between the treatments with nitrites and ferulic acid (p > 0.05) and all values were within the ranges established for these nutrients. Regarding the moisture content, although there was a difference between treatments (p < 0.05), the values found were within the reported range (5–15%) in dried meat. Treatment with nitrites had the highest sodium content (p < 0.05), although all treatments surpass the daily consumption of sodium recommended by the World Health Organization. In addition, color differences would not be noticeable to the human eye. Treatments with ferulic acid exhibited the highest (p < 0.05) antioxidant activity and the lowest lipid oxidation and total aerobic mesophile counts. Finally, the change in the formulation of dried meat using ferulic acid instead of nitrites was not perceptible to panelists in sensory evaluation. These findings suggest that the incorporation of ferulic acid, when added to dried meat, can improve its oxidative stability and increase its antioxidant activity. In conclusion, the use of ferulic acid at a concentration of 0.1% is recommended because, at this concentration, the antioxidant activity was greater, and the oxidation was below the threshold of perceived rancidity. However, further research is needed to study the effect of nitrite substitution using ferulic acid in combination with other potential natural antioxidants.

Sonoporation stimulates cell growth as it improves the permeability of the membrane and increases the uptake of impermeable molecules in the extracellular matrix. We evaluated the effects of substrates (whey, whole, and skim milk) and ultrasonic treatments (ultrasonication and thermosonication) on the antioxidant activity (AA) of water-soluble kefir postbiotics (WSKPs). The samples were evaluated in terms of antioxidant activity (ABTS, DPPH, FRAP, and ORAC), water-soluble protein content, proteolysis (SDS-PAGE profiles), and cell membrane permeability. The levels of AA in all WSKPs depended on the substrate and method of obtaining them. However, the WSKPs from whey had higher antioxidant activity with DPPH (11.11 mg TE/100 mL), ABTS (12.77 mg TE/100 mL), and FRAP (5.18 mg TE/100 mL). Also, the WSKPs from whey had the highest values for water-soluble protein (1.45–1.32 mg/mL) and proteolysis degree and the lowest percentage of dead cells (11.4–28%). These results suggest that the production of WSKPs from whey might add value to whey production. Furthermore, WSKPs have potential as a functional ingredient in the production of beverages or foods with antioxidant activity.

Postbiotics are recently gaining consumer attention for their potential health benefits. This study aimed to examine the effects of supplementation of a non-fermented dairy beverage with postbiotics derived from Lactobacillus acidophilus and Lactobacillus helveticus on antioxidant (DPPH, ABTS, FRAP, and ORAC), antimicrobial, and ACE-inhibition activities before and after in vitro digestion. Three dairy beverages were elaborated: without the addition of postbiotics (T0), with Lactobacillus acidophilus postbiotics (T1), and with Lactobacillus helveticus postbiotics (T2). Before in vitro digestion, T2 presented higher antioxidant activity (p < 0.05). And, after in vitro digestion, except by the ABTS method, T1 and T2 presented the highest antioxidant activities (p < 0.05) and bioaccessibility indexes (p < 0.05). Regarding ACE-inhibition activity, before in vitro digestion, there were no differences among treatments (p > 0.05), but after in vitro digestion, T1 and T2 presented the highest ACE-inhibition activities (p < 0.05) and bioaccessibility indexes (p < 0.05). An antimicrobial effect against Bacillus spp. and S. aureus was observed in Lactobacillus acidophilus and Lactobacillus helveticus postbiotics. However, L. acidophilus postbiotics did not present an antibacterial effect against E. coli. Such findings highlight the potential of postbiotics as functional ingredients to enhance the antioxidant and ACE-inhibition activities of non-fermented dairy beverages, further adding to their appeal as health-promoting dairy food.

Ferulic acid (FA) is an antimicrobial and antioxidant phenolic compound located in the cell walls of plants and therefore classified as a natural antioxidant. The objective of this study was to assess the antimicrobial and antioxidant potential of FA as a substitute for nitrites in the elaboration of dried meat (DM) . Four treatments were evaluated: DM without nitrites or FA (control treatment; CT), DM with nitrites (NT), DM with 0.05% of FA (FT05), and DM with 0.1% of FA (FT1). The antioxidant activity (ABTS, DPPH, and FRAP), lipid oxidation (TBARS), and microbiological quality were evaluated throughout DM shelf life. Protein, fat, and ash content were not different among NT, FT05, and FT1 (p > 0.05). NT and FT05 had lower moisture content (p < 0.05) compared to CT and FT1. And NT had the highest sodium content (p < 0.05). Regarding color, no differences (p > 0.05) were found among NT and FT05 in L* and a* values, but FT05 presented the highest b* value among all treatments (p < 0.05). However, color differences (ΔE) values between NT and FA treatments indicate that the color change is not noticeable to the human eye. Meanwhile, FT1 and FT05 exhibited the highest (p < 0.05) AA and the lowest lipid oxidation throughout their shelf life. Total aerobic mesophiles counts were detected only on day 1 and were lower (p < 0.05) in the treatments with FA. Finally, the change in the formulation of dried meat by using ferulic acid instead of nitrites was not sensorially detected by panelists. These findings suggest that incorporating natural antioxidants such as FA can improve the oxidative stability of dried meat, and it has a potential application as an antioxidant in meat products. However, further research is needed to study the effect of nitrite substitution using FA in combination with other potential natural antioxidants.