Paraprobiotics from water kefir grains probiotic strain: Obtainment and innovative approaches for functional fermented beverages

This study aimed to investigate the inactivation kinetics of Lacticaseibacillus paracasei MIUG BL80 strain, a probiotic lactic acid bacteria from the Microorganisms Collection of Dunărea de Jos University of Galati, Romania (the acronym MIUG and BL is a supplementary code in this collection for lactic acid bacteria), isolated from the microbiota of water kefir grains, through ultrasound and thermal treatments to produce paraprobiotics. Results indicate that complete inactivation of cells is achieved by treating a 25 mL volume of cell suspension (1 × 10 8 CFU/mL) with ultrasound at 80% intensity, for 20 minutes, followed by thermal treatment at 75°C for 30 minutes. The resulting paraprobiotics were incorporated into an innovative fermented beverage formula. Moreover, an innovative beverage was developed using 4% ( w/v ) spent coffee grounds, 2% ( w/v ) sugar, 10% ( w/v ) freeze-dried sourdough from whole rye flour, 15% ( w/v ) paraprobiotic, and 0.2% ( w/v ) starter yeast. The fermented product exhibits bioactive properties, including total titratable acidity of 13.48 ± 0.02 mL of 0.1 N NaOH, antioxidant activity of 2.30 ± 0.02 mM TE/mL, antimicrobial activity against Bacillus subtilis (12.00 ± 0.30 mm inhibition zone), Staphylococcus aureus (10.33±0.15 mm), and 86.41% inhibition against Aspergillus niger . Furthermore, the fermented beverage contains 102.72 ± 0.31μg/mL gallic acid, 34.48 ± 0.14 μg/mL protocatechuic acid, 3.89 ± 0.64 μg/mL 4-hydroxybenzoic acid, 8.62 ± 2.94 μg/mL caffeine along with cafestol and vanillic acid. The beverage also received favourable average scores on key consumer perception attributes, with colour (3.80) and aftertaste (3.53) being well appreciated, indicating an attractive appearance and a lasting, pleasant taste. The texture received a positive rating (3.47), suggesting a pleasing mouthfeel during consumption. Also, the potential of paraprobiotic beverages for long-term use or in vivo effects highlights the need for further research in future studies.