Combining a probiotic with organic salts presents synergistic in vitro inhibition against aquaculture bacterial pathogens

ABSTRACT This study aimed to evaluate 1) the in vitro effect of organic salts on the growth of the probiotic Lactobacillus plantarum and then 2) the combined use of a probiotic with organic salts on the in vitro inhibition of V. alginolyticus, A. hydrophila, E. coli, P. aeruginosa, and S. agalactiae. In vitro tests were performed with eight different organic salts, including butyrate, propionate, succinate, citrate, formate, fumarate, glutamate, and acetate, at two pH values (6.2 and 7.1) to determine their effect on the growth kinetics of L. plantarum. In addition, each organic salt was tested alone and in combination with L. plantarum to evaluate the inhibitory effect against the pathogenic bacteria noted above in either condition. Sodium citrate and formate inhibited the growth of L. plantarum, but sodium glutamate, succinate and fumarate stimulated it. Sodium propionate, butyrate, and acetate did not affect probiotic growth at all. Inhibition against all pathogens was significantly higher in the presence of the probiotic and lower pH. Comparing all organic salts at the two pH values, butyrate, acetate, and propionate exhibited more inhibition against V. alginolyticus than the others, while propionate had higher inhibition against A. hydrophila, E. coli, P. aeruginosa, and fumarate successfully inhibited S. agalactiae. Based on these results, it can be concluded that organic salts showed better in vitro inhibition against the aquaculture pathogenic bacteria tested when combined with the probiotic L. plantarum.

Avaliação da ação antimicrobiana in vitro de propionato de sódio sobre leveduras isoladas de ricotas / Evaluation of the anti microbial action in vitro of propionate of sodium about yeasts isolated of ricotta

Conforme a legislação, os conservantes alimentícios podem ser conceituados como “substâncias que impedem ou retardam a alteração dos alimentos provocada por microrganismos ou enzimas”. Dentre os fatores considerados para seleção de um conservador pode-se citar: pH, composição do produto, existência de outras substâncias inibidoras de desenvolvimento microbiano, atividade de água (Aa ou Aw), nível inicial de contaminação, microrganismo a ser inibido, facilidade de manipulação do conservante, impacto no paladar e custo. Das propriedades do alimento o pH é provavelmente a que mais tem influência no aumento da ação antimicrobiana do conservador. Os propionatos são eficientes contra bolores, têm pouca ação sobre a maioria das bactérias e nas concentrações normalmente empregadas não apresentam praticamente nenhum efeito contra as leveduras. O propionato de cálcio (INS -282), de potássio (INS 283) e de sódio (INS 281) são usados na concentração de 0,20 por cento em massas semi-prontas, recheadas ou não, para preparo de produtos forneáveis, doces ou salgados com umidade superior a 15 por cento, em mistura para produtos de panificação e confeitaria, picles, pizzas, pastéis, empadas, polentas pré-embaladas e com umidade superior a 15 por cento, em produtos de confeitaria e de panificação. Consoante os aspectos mencionados anteriormente, este trabalho teve como objetivo avaliar a ação antimicrobiana in vitro de propionato de sódio sobre leveduras isoladas de ricotas. (...)(AU)

According to the legislation, food preservatives may be defined as "sub- stances that impede or retard alterations in foods caused by microorganisms or enzymes", Among the factors taken into account in order to select a food preservative, the following can be mentioned: pH, product composition, presence of other susbtances that inhibit the development of microorganisms, aw, initial level of contamination, target microorganism, how easy it is to handle the food preservative, impact on flavor, and cost. Among the food properties, the pH is probably the one with the greatest influence upon the increase of the anti-microbial action of the food preservative. Propionates are efficient against moulds, and they have little influence upon the majority of bacteria and, at the concentrations used normally, they have no effect against yeasts. Calcium ( INS - 282 ), potassium( INS - 283 ) and sodium ( INS - 281 ) propionate are used at the concentration of 0.20% in pasta partly ready, with or without filling, as well as in the preparation of products ready to the baked, sweets or not, with humidity higher than 15%, and in mixtures for bakery products, pickles, pizzas, pastries, pre-packed polentas with humidity higher than 15%, bakery products. According to what has been mentioned before, the objective of this study was to evaluate in vitro anti - microbial action of sodium propionate upon yeasts isolated from ricotta. In order to achieve this goal, Petri dishes with sabouraud dextrose agar have been used (pH adjusted to 5.1) with the following concentrations of the food preservative ( O = control; 0.1; 0.15; 0.2; 0.3; 0.4 and 0.6% ) in which cultures previously grown in sabouraud dextrose broth (pH = 5.1) have been sewn in triples, by replica plating. After 21 days of incubation at 250C, it was observed that 1.13% of the tested yeasts were sensible to sodium propionate ( INS - 281 ) at concentration 0.1% and that 4.54% were inhibited from 0.15 to 0.6%. (AU)

Sodium Propionate To Control Clostridium botulinum Toxigenesis in a Shelf-Stable Beef Product Prepared by Using Combined Processes Including Irradiation.

The antibotulinal effect of sodium propionate was evaluated by a factorial-design experiment and by an inoculated-pack study on a shelf-stable beef product. Processing of samples involved curing, cooking, vacuum packing, and gamma irradiation. The factorial-design experiment involved 240 samples treated with 0, 0.8, 2.0, and 3.3% sodium propionate, challenged with 101 to 105 spores of type A Clostridium botulinum per package, irradiated with 2.5, 5, 7.5, and 10 kGy, and stored at 28°C for up to 4 months. In the pack study, 110 samples with 2% added sodium propionate were challenged with 108 spores of C. botulinum per package, irradiated with 12.5 kGy, and stored (28°C) for 8 months. Addition of 0.8% sodium propionate resulted in a delay (compared to control samples) in toxigenesis of 18 (5 kGy), 34 (2.5 kGy), and 34 (7.5 kGy) days, while no toxin was detected in samples irradiated with 10 kGy. Samples containing 2 and 3.3% sodium propionate were not toxic at any irradiation dose assayed. A safety level, expressed as the number of decimal reductions (DR = log 1/P) for the combination 0.8% sodium propionate and 10 kGy, was estimated to be >4.4. In the inoculated pack study, 2 of 107 samples became toxic, and the safety level treatment resulted in 10.7 DR. Sodium propionate in combination with other processing factors was very effective in preventing C. botulinum toxigenesis: it can be used as a further safety hurdle in the development of shelf-stable meat products.