Nonthermal pasteurization of beer by high pressure processing: modelling the inactivation ofsaccharomyces cerevisiaeascospores in different alcohol beers

Abstract

The industrial production of beer ends with a process of thermal pasteurization. In this research, the nonthermal pasteurization of beer by high pressure processing (HPP) was carried out. First, the effect of alcohol content on Saccharomyces cerevisiae ascospore inactivation at 400 MPa was studied. The number of ascospores in 0.0%, 4.8%, and 7.0% alc/vol beers for 10 min processing time decreased by 3.1, 4.9, and ≥ 6.0 log, respectively. The Weibull model fitted the ascospore inactivation by HPP in 0.0%, 4.8%, and 7.0% alc/vol beers. At 400 MPa, 7.2 s could ensure the minimum pasteurization of beers and for 600 MPa 5 s were enough for ≥ 7 log reductions. The overall flavour of HPP vs. untreated beers was evaluated for a lager and an ale, with no significant differences between the untreated and HPP beers. Thus, nonthermal HPP is a feasible technology to pasteurize beer with different alcohol contents without heat. ARTICLE HISTORY

Application and possible benefits of high hydrostatic pressure or high-pressure homogenization on beer processing: A review

“…However, after 10 min process this difference become greater and the beer with higher alcohol content presented a greater ascospore’s inactivation. This can similarly be also observed in the usual thermal pasteurizaton process of beer and for this reason results of HHP on beers with 0.0% of alcohol can be compared to those obtained with juices (Milani et al., 2016b). These authors also verified that 300 MPa for 120, 7.2 and 1.0 s is enough for pasteurization of 0.0%, 4.8% and 7.0% alcohol beers, respectively.…”

“…They observed a spore count reduction of 2.5 log cycles after 200 MPa/30 min, 300 MPa/27 s or 400 MPa/12 s. According to the authors, this inactivation might occur during compression phase, since a greater inactivation was verified at the initial part of the survival curve, especially at 400 MPa. In another study, Milani et al. (2016b) observed no growth of S. cerevisiae spores (≥7 logs reductions) at 600 MPa and 5, 15, 20 and 30 s.…”

“…Milani et al. (2016b) applied hydrostatic pressure to lager beers with different alcohol contents (0.0%, 4.8% and 7.0%) to see if the alcohol has some influence together with the high pressure on S. cerevisiae ascospore’s inactivation.…”

Effects of high‐pressure processing on fungi spores: Factors affecting spore germination and inactivation and impact on ultrastructure

“…For example, Milani, Ramsey, and Silva () reported 2.5 logs of S. cerevisiae ascospores inactivation after a pressure treatment at 400 MPa for 12 s at 25 °C in 4% ethanol beer. These inactivation values could be associated with a synergistic effect between pressure and the ethanol content; nevertheless, Milani and Silva () reported total ascospore loads (7 log units) after a pressure treatment at 600 MPa for 30 s at temperatures below 36 °C regardless the ethanol content (0, 4.8 and 7.0%) of beer, which shows the efficacy of pressure alone to destroy ascospores of S. cerevisiae , which may be interesting for the pasteurization of alcoholic beverages.…”

“…Fungi spores are commonly found in fruit juices and concentrates, yogurts, smoke‐dried or cured meat products, bakery products, ready‐to‐eat meals, among others (Fornal, Parfieniuk, Czeczko, Bilinska‐Wielgus, & Frac, ; Garcia et al., ; Montanha et al., ; Sant'Ana et al., ). Generally, these spores are inactivated by conventional thermal pasteurization; nevertheless, there are a few cases of heat‐resistant molds, such as the genera Byssochlamys spp., Neosartorya spp., and Talaromyces spp., among others, that are able to survive thermal pasteurization as applied in the industry (Evelyn & Silva, ; Santos et al., ) or by heat‐resistant yeasts that spoil fermented alcoholic beverages, such as beer (Evelyn, Milani, & Silva, ; Milani & Silva, ).…”