Nonthermal pasteurization of beer by high pressure processing: modelling the inactivation of saccharomyces cerevisiae ascospores 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.

KEYWORDS:

• Alcoholic beverages
• high hydrostatic pressure
• sensory
• yeast
• spores
• stability

Acknowledgements

The support of Prof. Richard Gardner, Keith Richards, and Miguel Roncoroni from the School of Biological Science at the University of Auckland is acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Filipa Silva has completed a five year Food Engineering Bachelor Degree in the Superior School of Biotechnology, Catholic University of Portugal, and a two year Master of Engineering at the University of Florida, USA, focusing Postharvest Technology and Distribution of Perishable Fruits and Vegetables. In 2000 she concluded a PhD in Biotechnology in the field of Food Science and Engineering. She has been teaching in tertiary education institutions food related courses since 1995. Her research activity and interests are in Food Process Engineering, in particular studying the effects of new food preservation technologies (e.g. high pressure processing, HPP), on food safety and shelf-life, and the design of proper pasteurization processes. Her expertise in microbiology and enzymes are helpful for studying the effect of emerging food preservation technologies on food spoilage microbes and enzymes.

Elham Alami Milani is a PhD graduate of the Chemical and Material Engineering, Faculty of the Engineering University of Auckland (UoA). She has a Chemical Engineering Bachelor degree from Science and Research Azad University in Iran, 2004. From 2004 to 2011, she was involved in several Oil and Gas projects as a project engineer such as 15 & 16 Phase - South Pars, Hengam, and Abouzar Off-shore Gas projects. She is currently employed as a teaching assistant at University of Auckland. Scientific interests of Dr. Milani are focused on Saccharomyces cerevisiae and the yeast ascospores, thermal and non-thermal pasteurization methods of alcoholic drinks, including pulsed electric fields, high hydrostatic pressure, and power ultrasound technologies.

ORCID

Filipa V. M. Silva http://orcid.org/0000-0003-4700-2938

Additional information

Funding

Project n. [3708802] ‘Nonthermal pasteurization of beer and non-alcoholic beverages’ funded by Morton Coutts grant, Dominion Breweries (Auckland, New Zealand) is acknowledged.