Craft Beer Produced by Immobilized Yeast Cells with the Addition of Grape Pomace Seed Powder: Physico-Chemical Characterization and Antioxidant Properties.

The aim of this study was to produce and to characterize craft beer fermented by immobilized yeast cells with the addition of Prokupac grape pomace seed powder (2.5% and 5%), to obtain a beer enriched with phenolic compounds and improved sensory characteristics. The immobilization of the yeast cells was performed by electrostatic extrusion, while the obtained calcium alginate beads were characterized by light and scanning electron microscopy. Phenolic and hop-derived bitter compounds in beer with or without grape pomace seed powder (GS) phenolics were identified using UHPLC Q-ToF MS. The results indicated that GS adjunct significantly shortened the fermentation process of wort and increased the content of phenolic compounds, especially ellagic acid, flavan-3-ols and pro(antho)cyanidins in the final products compared to the control beer. A total of twenty (iso)-α-acids and one prenylflavonoid were identified, although their levels were significantly lower in beers with GS phenolics compared to the control beer. Beers with GS phenolics showed good antioxidant properties as measured by the reduction of ferric ions (FRP) and the scavenging of ABTS•+ and DPPH• radicals. The concentration of immobilized viable yeast cells was higher than 1 × 108 CFU/g wet mass after each fermentation without destroying the beads, indicating that they can be reused for the repeated fermentation of wort. Beers produced with 5% GS added to the wort exhibited the best sensory properties (acidity, astringency, bitterness intensity, mouthfeel, aftertaste and taste), and highest overall acceptability by the panelists. The results showed that grape pomace seed powder present a promising adjunct for the production of innovative craft beer with good sensory properties and improved functionality.

Design of biopolymer carriers enriched with natural emulsifiers for improved controlled release of thyme essential oil.

This work aims to characterize a novel system for thyme essential oil delivery based on the combination of natural emulsifiers (soy protein and soy lecithin) and alginate, produced using the extrusion technique. The formulations are optimized concerning alginate and soy protein concentrations (both 1 to 1.5 wt.%), and consequently lecithin amount, in order to achieve spherical beads in the range 2.0 to 2.3 mm and 1.2 to 1.4 mm, wet and dry, respectively. Fourier-transform infrared analysis was performed, proving that there are interactions between all components. Lecithin-soy protein synergistic combination improved entrapment efficiency of total polyphenols (for nearly 12%) and decreased thymol release in a simulated gastric solution for nearly 35%, in comparison with beads without lecithin. The addition of lecithin enhances the thermal properties of the polysaccharide-protein systems at 50 °C after 3 hr of heating. The mechanical stability of the biopolymer carriers is improved with lecithin addition and the elastic modulus varied from 80.06 to 123.7 kPa, depending on the formulation. Alginate/soy protein/lecithin are effective carriers for the encapsulation, protection, and controlled release of thyme essential oil. PRACTICAL APPLICATION: There is unfortunately growing human resistance to antibiotics. This work offers a novel system for effective protection and controlled release of thyme essential oil in the small intestine. The mechanical and thermal properties of the carrier were estimated as they indicate how the beads will be able to resist stress during their incorporation into food (i.e. cookies-mixing, baking). The proposed approach offers ''green advantage'' as arises from all-natural materials.

Application of whey protein and whey protein hydrolysate as protein based carrier for probiotic starter culture.

The main object of study is application of whey protein concentrate (WPC) and whey protein hydrolysate (WPH) for probiotic encapsulation. The controlled enzymatic hydrolysis was applied to change technological properties of WPC what leads to obtained different carriers. Probiotic carriers (beads) were made by electrostatic extrusion. Bead properties (mechanical properties, FTIR fingerprint, cell release) and parameters of fermentation were examined. According to cell release, it can be concluded that WPH build less porous matrix with alginate than WPC. Beads with WPH contained more living cells and suffered more changes during fermentation than beads with WPC. Probiotic viability in simulated gastrointestinal conditions (SGIC) is the most critical parameter for probiotic encapsulation. Probiotic encapsulated in protein-alginate beads survived SGIC with more than 96% viable cells, compared to 37.43% for free culture. According to all examined parameters, it can be concluded that WPH builds more suitable carrier for probiotic culture than WPC.

Effect of immobilisation materials on viability and fermentation activity of dairy starter culture in whey-based substrate.

BACKGROUND: The main objectives of the paper were to study influence of immobilisation of dairy starter culture 'Lactoferm ABY 6' on fermentation and probiotic potential of fermented whey-based substrate. RESULTS: Fermentation with free cells takes 1.5 h less than fermentation with encapsulated cells, but samples with encapsulated cells have better characteristics after 28 days of storage. Chitosan coating provides additional protection of cells in bile salt solution (95.86% of viable cells compared to the initial number) and simulated gastric juice (37.8% for pH 2.5) compared to the alginate beads (94.54% in bile salt solution and 36.18% in simulated gastric juice for pH 2.5). Free cells had a drastic reduction in the number of viable cells (83.0% in bile salt solution and no viable cells in simulated gastric juice for pH 2.5). CONCLUSION: Samples with alginate beads and chitosan-coated alginate beads have significantly (P < 0.05) higher viable cell count than samples with free cells, during 4 h monitoring survival at pH 2.5, pH 3.0 and 0.3% bovine bile solution. These beads can be used to improve survival of probiotic cells in fermented whey-based beverage during storage and consummation, which improves the quality of the product.