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Encapsulation is a commonly used tool in the pharmaceutical and nutraceutical fields to protect the compound of interest from adverse environmental conditions (i.e., production process, gastrointestinal transit, immune defense) or to ensure a target or controlled release of an active principle. However, capsules can also be used as reactors, by which probiotics can carry out a fermentation with improved process performances. In the present work, hydrolyzed oatmeal capsules were developed as mini-bioreactors, segregating the probiotic strain in active fermentation and allowing the metabolite release. The aim was to study how composition can influence the ability to ferment and the confinement of microorganisms. Four different capsules formulations were studied varying CaCl2 and alginate concentrations [(i) 0.5% alginate-0,1 M CaCl2; (ii) 1% alginate-1 M CaCl2; (iii) 1% alginate-3 M CaCl2; (iv) 1% alginate-5 M CaCl2]. The capsules were suspended in the same hydrolyzed oatmeal suspension used to produce them and left to ferment at 37°C for 24h. Microbiological and chemical analyses were carried out on both capsules and external liquids. An increase in the bacterial concentration of about 3 logs was recognized for all the first three formulations in the capsules, while a growth inhibition was observed for the (iv) formulation, the only formulation for which microorganism confinement was also noted. The highest lactic acid production (15.9 g/L) was observed for the (ii) formulation, while the lowest one was also recorded for formulation (iv). Optical analyses confirmed the different structural characteristics of the capsules.

Encapsulation is an innovative promising technique in the field of biotechnology, both for confining live microorganisms to promote their viability during processing and for the target delivery in the gastrointestinal tract, and for trapping active metabolites produced during a fermentation process within a carrier material, allowing their gradual release. During this work, a probiotic strain, Lacticaseibacillus paracasei CBA L74, was encapsulated using a hydrolyzed oatmeal suspension as a prebiotic carrier, by extrusion technique with CaCl2 a (1M) and alginate (1% w/v). The mini-bioreactors obtained were suspended in three different external liquids, (the same hydrolyzed oatmeal suspension used for the capsule production; a hydrolyzed oatmeal suspension with a modified pH equal to 3.3, and a hydrolyzed oatmeal suspension formulated by adding a specific concentration of dead bacteria) to evaluate whether the external liquid can help the confinement of the bacteria in the capsules. For this purpose, the fermentation process was carried out at 37°C for 24h; both capsules and external liquids were characterized by microbiological and chemical analyses. The maximum bacterial growth ( 109 CFU/mL) was reached in all the capsules, except for those suspended in the formulation with a modified pH where a bacterial charge of 3.5 x 108 CFU/mL was obtained; in any case, the bacterial confinement was not obtained. The highest lactic acid concentration (15.9 g/L) was observed for the capsules suspended in the same oatmeal suspension used for encapsulation, while the lowest one was obtained in the external oatmeal liquid with a modified pH.

In recent years, scientific research and industries have been focusing on the application of biological treatments aimed at imparting functional properties to waste products from food industries according to the principles on which the circular economy model is based, namely, the recovery, valorisation, and reuse of wastes. This work aimed at exploring the possibility of valorising waters from the blanching process of dried navy beans through lactic acid fermentation using Lacticaseibacillus paracasei CBA L74 as a starter. Two samples at different solid concentrations (0.75 °Bx and 1.25 °Bx) were fermented, and, in both cases, a bacterial load of 8 Logs and a lactic acid concentration of approximately 1.3 g/L were reached, despite the lack of nutrients. An unusual pH trend, characterised by an initial decrease and unexpected final rise, was observed during the fermentation of both samples: simultaneously, an increase in protein content was observed, suggesting that the proteolytic action of the microorganism could be responsible for the release of pH-increasing substances. In both cases, a slight increase in total polyphenols (approximately 23.3–33.72%) and flavonoids (approximately 42.3–52%) due to fermentation was observed, with a corresponding improvement in antioxidant capacity (approximately 25.32–37.72%). A significant increase in saponin concentration was determined for the most concentrated blanching water (from 2.87 ± 0.28 to 6.68 ± 0.69 mgOAE/mL), leading to an improvement in foaming properties and an enhanced capacity to produce stable emulsions. The obtained results confirmed the possibility of reducing water consumption from blanching operations, as well as finding valorisation opportunities for this side stream through a safe and inexpensive fermentation treatment.

The concept of postbiotic has been attracting the attention of the scientific community and several industrial realities to develop new claims and new market segments for functional fermented products. The aim of this work was to develop a process to produce an oat-based postbiotic ingredient to be used in personal care cosmetic formulations. A hydrolyzed oatmeal suspension was fermented using Lacticaseibacillus paracasei CBA L74 as starter culture, at 37 °C for 48 h by controlling the pH; then the bacterial charge was inactivated by a mild thermal treatment at 80 °C for 30 s, obtaining a postbiotic. The effect of different process steps, hydrolysis, sterilization, fermentation, and inactivation phases, on lactic acid concentration, total polyphenolic content, antioxidant activity, tyrosinase inhibition activity and Sun Protection Factor value was investigated, demonstrating the potential cosmetic applications. The maximum bacterial growth and lactic acid production were achieved after 24 h of process, with a cell density and a lactic acid concentration of 3.05 × 109 CFU/mL and 8.60 g/L, respectively. The total phenolic content and the antioxidant activity reached their maximum values (2.5 mgGAE/mL, EC50 = 2.2 mg/mL and 1.38 × 10−2 mmol Fe2+/g and 7.3 × 10−3 mmol TE/g, respectively) after the sterilization treatment; the maximum tyrosinase inhibition of 50.6%, corresponding to a sample concentration of 16 mg/mL, was found after 24 h of fermentation process. Fermentation did not show an impact on UV shielding ability and the SPF value decreased during the process.