Rast plesni vrste Aspergillus flavus in tvorba aflatoksina B1 v značilnih razmerah za izdelavo suhih salam

Šturm, Zala (author), Jeršek, Barbka (mentor), Polak, Tomaž (comentor)

Plesni vrste Aspergillus flavus tvorijo sekundarne metabolite, imenovane aflatoksini, ki veljajo za najbolj toksične mikotoksine. Aflatoksini neposredno in posredno vplivajo na zdravje ljudi in živali ter imajo velik gospodarski vpliv. Ker plesni vrste A. flavus lahko rastejo tudi na suhih salamah, je bil cilj študije oceniti vpliv razmer pri njihovi izdelavi na rast plesni in tvorbo aflatoksina B1 (AFB1). Spremljali smo vpliv časa (7, 14, 21 dni), temperature (10 °C, 15 °C, 25 °C), vrednosti aw (0,98, 0,99, 0,95), vrednosti pH (6,7, 6,3, 5,4), sestave gojišča ter vpliv dodatka izrabljenega gojišča mlečnokislinskih bakterij (MKB) vrste Lactiplantibacillus plantarum. Rast plesni smo spremljali z merjenjem premera kolonij, tvorbo AFB1 pa s kromatografsko metodo UPLC䀒MS/MS. Ugotovili smo, da ima čas na rast plesni in tvorbo AFB1 bistven vpliv, saj sta se oba preiskovana parametra s časom linearno povečevala. Optimalna temperatura za rast plesni in tvorbo AFB1 je bila 25 °C. Optimalna vrednost aw za rast je znašala 0,98, za tvorbo AFB1 pa 0,95, kjer je bila po 21 dneh inkubacije pri 25 °C na gojišču YES9554 (kvasni ekstrakt z dodatki, aw 0,95 in pH 5,4) maksimalna izmerjena koncentracija AFB1 (116,84 g/g), sledilo je gojišče YES9563 (aw 0,95 in pH 6,3) s 110,87 g/g AFB1. Vrednost pH je imela med vsemi preiskovanimi parametri najmanjši vpliv. Ugotovili smo tudi, da je sestava gojišča bistveno vplivala na rast plesni, še bolj pa na tvorbo AFB1, saj smo določili tudi do 95 % nižje koncentracije AFB1 v gojiščih CMGY (kuhano mesno gojišče z glukozo in kvasnim ekstraktom) v primerjavi z gojišči YES. Dodatek izrabljenega gojišča MKB je vplival na zmanjšano tvorbo AFB1, saj smo pri 10 % dodatku določili zmanjšano tvorbo AFB1. Rezultati študije kažejo na obsežnost in prepletenost vplivov okoljskih razmer na rast plesni vrste A. flavus in tvorbo AFB1 v razmerah, značilnih za proizvodnjo suhih salam, ter nakazujejo nekatere parametre (temperatura, vrednost aw, dodatek izrabljenega gojišča MKB), s katerimi lahko zmanjšamo potencial tvorbe AFB1 v teh izdelkih.

• Language: Slovenian
• Keywords: plesni, Aspergillus flavus, aflatoksin B1, suhe salame, rast plesni, Lactiplantibacillus plantarum, mlečna kislina
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [Z. Šturm]
• Year: 2024
• PID: 20.500.12556/RUL-158537
• UDC: 579.67:582.282:615.9:637.52
• COBISS.SI-ID: 199095043
• Publication date in RUL: 15.06.2024

Secondary language

• Language: English
• Title: Growth of Aspergillus flavus and aflatoxin B1 formation in conditions typical for dry salami production

Abstract

Aspergillus flavus produce secondary metabolites called aflatoxins, which are considered the most toxic mycotoxins. Aflatoxins directly and indirectly affect human and animal health and have a major economic impact. As A. flavus grow also on fermented meat products, the aim of this study was to assess the impact of the conditions that are typical for production of dry salami on mould growth and aflatoxin B1 formation. The influence of time (7, 14, 21 days), temperature (10 °C, 15 °C, 25 °C), aw (0.98, 0.99, 0.95), pH (6.7, 6.3, 5.4), medium composition and the addition of spent medium after growth of lactic acid bacteria (LAB), namely Lactiplantibacillus plantarum, were monitored. Mould growth was determined by measuring the diameter of the colonies and AFB1 production was monitored by UPLC-MS/MS chromatography. We found that time had a significant effect on mould growth and AFB1 production, as both parameters increased linearly with time. The optimum temperature for mould growth and AFB1 production was 25 °C. The optimum aw for growth was 0.98 and for AFB1 production was 0.95, where after 21 days of incubation at 25 °C on YES9554 (Yeast extract with sucrose, aw 0.95, pH 5.4) medium the maximum AFB1 concentration was 116.84 g/g, followed by YES9563 (aw 0.95, pH 6.3) medium with 110.87 g/g AFB1. The pH had the lowest effect on mould growth and AFB1 production among all the parameters investigated. We also found out that the composition of the medium had a significant effect on mould growth, and even more on AFB1 production, as we detected up to 95 % lower AFB1 concentrations in CMGY (cooked meat agar with glucose and yeast extract) media compared to YES media. The 10 % addition of spent LAB medium reduced AFB1 production. The results of the study show the complexity of the effects of environmental conditions on A. flavus growth and formation of AFB1 in conditions typical for production of dry salami and indicate some parameters (temperature, aw, addition of spent MKB medium) that can be used to reduce the potential for AFB1 formation in these products.

• Keywords: moulds, Aspergillus flavus, aflatoxin B1, dry salami, mould growth, Lactiplantibacillus plantarum, lactic acid