A YOGURT CONTAINING BLACKCURRANT AND Lentilactobacillus kefiri: FROM FERMENTATION KINETICS TO FUNCTIONAL CHARACTERIZATION

BOCKOR SABRINA; SOL GUAITA; ROCIO CORFIELD; ROSET VIOLETA; GORDILLO TANIA; RUZAL SANDRA M.; PALOMINO MARÍA MERCEDES; ALLIEVI MARIANA C

Buenos Aires Argentina

Congreso; XVIII CONGRESO ARGENTINO DE CIENCIA Y TECNOLOGÍA DE ALIMENTOS; 2023

CYTAL

ABSTRACTProbiotic dairy products are highly desirable functional foods due to their health benefits,but their efficacy depends on the viability of probiotics throughout the product's shelf lifeand in the gastrointestinal tract. Blackcurrant (BC) and its derivatives are known for theiroutstanding antioxidant capacity and multiple health benefits, as well as theirantimicrobial properties against pathogenic microorganisms, making them an idealingredient in dairy products. However, the effects of BC and its interaction with startersand probiotics during the manufacturing process, especially in yogurts, remain largelyunexplored. In previous works using the mini-yogurt system, we showed that BC wouldhave an effect on the fermentation process, shortening the production time. The firstobjective of the current research is to study the fermentation kinetics of starters culturesin yogurt 1% and 2.5% BC formulations. While the concentration of BC did not affectthe growth of Lactobacillus bulgaricus, it did decrease the growth of Streptococcusthermophilus proportionally to the BC content. Using lactate, we recreated the aciditygenerated by BC and found that pH was not the only cause of growth inhibition forStreptococcus thermophilus, but there is another biomolecule in BC that generates anantimicrobial effect. However, the CFU values obtained were sufficient for therequirements of yogurt and reduced the product's elaboration time by almost half. Thesecond objective was to characterize the chosen 1% BC formulation withLentilactobacillus kefiri (Len. kefiri). We seek to obtain information on thephysicochemical characteristics pre and post-fermentation of yogurt containingblackcurrant. For this, viable cell count on differential media, pH, syneresis, color andantioxidant activity were evaluated. The incorporation of BC did not inhibit the probioticLen. kefiri, which maintained viability during the fermentation process and during theshelf life of the product, reaching log CFU/ml values of 7.71±0.05 after 21 days. As adesirable characteristic, the presence of BC reduced the syneresis percentage of the yogurtfrom (77.7±0,9)% to (70.1±0.5)%. A measurement of the CIELAB color space wasconducted, and the recorded values exhibited slight modifications during refrigeration,with a ΔE* value considered normal. The antioxidant capacity of the formulation wasmeasured using FRAP and ABTS•+ methods, giving values of (0.100±0.010) and(0.282±0.001) mg EAG/g of yogurt, respectively. This means a 28% increase inantioxidant activity compared to the active ingredient alone. In conclusion, this studyprovides valuable insights into the fermentation kinetics of yogurt in the presence of BC.The findings suggest that acidity is not the only factor affecting fermentation, but there isalso an inhibitory effect on one of the starter cultures. Additionally, a probiotic yogurtwith 1% BC was formulated, and its production time was reduced. It is noteworthy thatdespite the potential inhibitory effects of polyphenols on probiotic bacteria, BC did notadversely affect the survival of Len. kefiri. Therefore, a probiotic yogurt with antioxidantcapacity and acceptable parameters over time was obtained.