Výskum probiotík pre akvakultúru je v ranom štádiu a pre ich implementáciu je potrebné vykonať ešte množstvo experimentov. Laktiplantibacily patria medzi mikroorganizmy, ktoré sa najčastejšie používajú na prípravu probiotických preparátov. Doterajšie výsledky nie sú postačujúce, práve preto sú potrebné ďalšie štúdie. Výber probiotík pre akvakultúru a ich vývoj pre komerčné využitie v akvakultúre je mnohostupňový a multidisciplinárny proces vyžadujúci si v prvej etape základný a neskôr aj aplikovaný výskum a posúdenie jeho použitia v praxi. Cieľom štúdie bolo pripraviť probiotické krmivo pre ryby s využitím pomocných látok a následne sledovať prežívateľnosť probiotických bakteriálnych buniek v krmive počas 9-mesačného skladovania pri chladničkovej (4 °C) a izbovej teplote (22 °C). Na prípravu krmiva bol použitý kmeň Lactobacillus plantarum R2 Biocenol™ (CCM 8674) (podľa novej taxonómie Lactiplantibacillus plantarum), potenciálne využiteľný pre probiotické účely v akvakultúre. Lepšia prežívateľnosť probiotických bakteriálnych buniek bola zaznamenaná vo vzorkách krmiva A (Aquatex 41 HMD) v porovnaní so vzorkami probiotických peliet B (Inicio 918-2). Keďže oxidácia mastných kyselín v krmive ovplyvňuje nutričnú kvalitu jednotlivých komponentov krmiva, predpokladáme, že vyššie množstvo oleja v krmive B negatívne ovplyvnilo prežívateľnosť probiotických bakteriálnych buniek. Najvyššie počty životaschopných probiotických baktérií boli zaznamenané pri 4 °C skladovania krmiva. Po 9 mesiacoch skladovania pri chladničkovej teplote počty laktiplantibacilov vo vzorkách krmiva A klesli z hodnoty 7,30 log10KTJ/g na počet 5,57 log10KTJ/g. Teplota je považovaná za rozhodujúci faktor ovplyvňujúci životaschopnosť a prežívateľnosť probiotických baktérií počas doby skladovania.
Research in probiotics for aquaculture is at an early stage of development and much work is still needed. Lactiplantibacilli belong to the microorganisms most frequently used to prepare the probiotics. The available information is inconclusive, since few experiments with sufficiently robust design have been conducted to permit critical evaluation. The development of probiotics applicable to commercial use in aquaculture is a multistep and multidisciplinary process requiring both empirical and fundamental research, full-scale trials, and an economic assessment of its use. The aim of the study was to prepare a probiotic aquafeed via excipients and subsequently to observe the survival of probiotic bacterial cells in the feed during the nine months storage period at a refrigerator (4 °C) or room temperature (22 °C). The strain Lactobacillus plantarum R2 Biocenol™ (CCM 8674) (according to the new taxonomy Lactiplantibacillus plantarum), potentially usable as a probiotic in aquaculture, was administered to prepare the aquafeed. Better survival of probiotic bacterial cells was recorded in a samples of pellets A (Aquatex 41 HMD) compared to the samples of probiotic pellets B (Inicio 918-2). Since oxidation of fatty acids in feed affects the nutritional quality of individual feed components, we assume that higher amounts of oil in feed B negatively affected the survival of probiotic bacterial cells. The highest numbers of viable probiotic bacteria cells were recorded at 4 °C storage of probiotic feed samples. The number of lactiplantibacilli dropped from 7.30 log10CFU . g–1 to 5.57 log10CFU . g–1 after the nine months storage period of feed samples A at 4 °C. Temperature is considered as a critical factor influencing probiotic viability and survival during storage period.
Flesh and fatty acid compositions, total volatile basic nitrogen (TVB-N), lipid oxidation and aerobic plate count, Enterobacteriaceae, psychrotrophic bacteria were determined in raw and smoked mackerel during cold storage (three groups differing in way of packaging; unpacked (UP), vacuum packaging (VP) and modified atmosphere (MAP) at 7, 14, 21, 28, 35, and 42 days. The protein, fat content and n-3 polyunsaturated fatty acids increased after smoking. The pH value and TVB-N were significantly higher in unpacked mackerel. Initial malondialdehyde concentration in raw mackerel was lowered after smoking and then lipid oxidation was the most pronounced in unpacked mackerel. Hot smoking, vacuum packaging, and modified atmosphere reduced bacterial growth, while the microbial contamination in all groups was below the limits during the whole period of storage. However, physicochemical properties of unpacked mackerel exceeded the limits from day 35 on. The present study indicates a lowering of products of secondary lipid oxidation after smoking followed by accelerated lipid degradation during cold storage of unpacked smoked mackerel. It is suggested that the smoking process and appropriate packaging method can protect lipids as well as valuable polyunsaturated fatty acids from oxidation. Vacuum packaging and modified atmosphere ensured microbial quality and protein and lipid stability. Their use is recommended for extending the shelf life of smoked fish considering the initial microbial and also chemical quality before and after smoking.
