Pasteurization of Beer by Non-Thermal Technologies

The pasteurization of beer occurs at the end of the industrial production, after fermentation. Generally, a mild thermal process (60°C) is employed aiming to inactivate the fermenting yeast and potential spoilage microorganisms, thus extending the beer shelf-life at room temperature. The heat treatment negatively affects the original beer freshness and flavor. In this study, beer pasteurization using emerging non-thermal technologies, namely, highpressure processing (HPP), pulsed electric fields (PEF), and ultrasound (US), was reviewed, including the effect on microbial inactivation and beer quality. The combination of non-thermal methods with mild heat for more efficient pasteurization of beer was also reviewed. All technologies caused microbial inactivation in beer. However, room temperature HPP treatment was the most efficient method, delivering the minimum 15 PU (pasteurization units) to beer after seconds (e.g., 300 MPa for 27 s), as opposed to thermal and TS treatments which required several minutes, while causing a negative impact on beer sensory. As expected, PEF + heat caused a higher microbial inactivation than PEF alone, and yeast ascospores were more resistant than vegetative yeast cells. Non-thermal PEF (35–45 kV/cm) caused 3–5.8 log reductions in vegetative bacteria. Studies on thermal assisted PEF and ultrasound combined with low heat (50–55°C) showed processing times in the magnitude of microseconds for PEF pasteurization and 0.5–2min (depending on the temperature) for TS pasteurization. With respect to impact of these technologies on beer quality, HPP, thermosonication (TS), high pressure homogenization (HPH), and dense phase CO2 (DPCD) treatments revealed less effect on beer sensory properties, better retaining the freshness of original beer, compared to thermally processed beers.info:eu-repo/semantics/publishedVersio

Defining winery processing conditions for the decontamination of must and wine spoilage microbiota by Pulsed Electric Fields (PEF)

This study investigated the PEF-resistance of Saccharomyces bayanus, Brettanomyces bruxellensis, Lactobacillus plantarum, and Oenococus oeni in must or wine under continuous PEF processing. Results showed the capacity of PEF to achieve 3.0-log10-cycles (CFU/mL) of inactivation of all the microorganisms under moderate conditions (< 155 kJ/kg). Developed tertiary models accurately predicted the effect of PEF parameters on microbial inactivation, and Monte Carlo simulation considered the variability of factors and the maximum assumable microbial load in the final treated product. Results showed that PEF-treatments at 15 kV/cm and 129 or 153 kJ/kg would ensure the adequate decontamination (< 10 CFU/mL) of spoilage microorganism in must or wine, respectively. Industrial relevance: PEF technology has been shown to achieve adequate levels of microbial inactivation (3-log10) in must and wine under industrial applicable processing parameters, making it a suitable alternative to SO2 or sterilizing filtration for microbial control in winemaking. Reductions of 3-log10 CFU/mL of must and wine microbiota were found by continuous flow PEF-processing at 15 to 25 kV/cm and 175 to 148 kJ/kg, parameters applicable at industrial scale at 1 ton/h

Emerging Trends in Beverage Processing

Emerging Trends in Beverage Processing describes several non-thermal emerging technologies and biotechnologies. The use of non-thermal technologies represnts the future of food processing because due to the ability of such technologies to increase the shelf life, preserving nutritional and sensory quality. This book considers several promising technologies, such as: hyperbaric storage, ultrasound, high pressure homogeneization, pulsed light, cold plasma and pulsed electric fields, together with other emerging biotechnologies

Wine Spoilage Yeasts: Control Strategy

Traditionally in winemaking, sulphur dioxide (SO2) is chemically the most widely used for microflora control as antimicrobial preservative. Other tested compounds for selective yeast control are sorbic and benzoic acids. Herein, we discuss the effectiveness and the application of traditional and novel treatments and biotechnologies for chemical and biological control of wine spoilage yeasts. The versatility of the killer toxins and the antimicrobial properties of natural compounds such as carvacrol, essential oils and bioactive peptides will be considered. Some of the wine spoilage yeasts that are intended to control belong to the genera Zygosaccharomyces, Saccharomycodes and Dekkera/Brettanomyces, but also the non-Saccharomyces yeasts species dominating the first phase of fermentation (Hanseniaspora uvarum, Hansenula anomala, Metschnikowia pulcherrima, Wickerhamomyces anomalus) and some others, such as Schizosaccharomyces pombe, depending on the kind of wine to be produced

Study of strawberry flavored milk under pulsed electric field processing

Few studies exist on flavored milk processed by pulsed electric fields (PEF). The main concern is product stability. This study aimed to analyze the degradation of coloring agent Allura Red in strawberry milk under PEF. Four systems were tested containing Allura Red: two commercial milks and two model systems. PEF conditions were 40 kV/cm, 48 pulses (2.5 μs), and 55 °C; coloring agent was quantified via RP-HPLC. After processing, only minor changes were observed in color, Allura Red concentration, and pH. During storage (32 d) at refrigerated conditions (4 °C) commercial samples maintained pH above 6. Model systems dropped below pH 6 after 10 days of storage. Color of samples showed important decrease in a⁎; hue angle and chroma changed during storage. HPLC analysis reported a bi-phasic effect in Allura Red concentrations versus time. Concentration changed, reaching a maximum value during the middle of storage, possibly attributed to microbial growth, pH reduction, or interaction of proteins. However, PEF affected the stability of Allura Red in milk when additional ingredients were not added to the product

Emerging Non-Thermal Technologies as Alternative to SO2 for the Production of Wine

ReviewSO2 is an antioxidant and selective antimicrobial additive, inhibiting the growth of molds in the must during the early stages of wine production, as well as undesirable bacteria and yeasts during fermentation, thus avoiding microbial spoilage during wine production and storage. The addition of SO2 is regulated to a maximum of 150–350 ppm, as this chemical preservative can cause adverse effects in consumers such as allergic reactions. Therefore, the wine industry is interested in finding alternative strategies to reduce SO2 levels, while maintaining wine quality. The use of non-thermal or cold pasteurization technologies for wine preservation was reviewed. The effect of pulsed electric fields (PEF), high pressure processing (HPP), power ultrasound (US), ultraviolet irradiation (UV), high pressure homogenization (HPH), filtration and low electric current (LEC) on wine quality and microbial inactivation was explored and the technologies were compared. PEF and HPP proved to be effective wine pasteurization technologies as they inactivate key wine spoilage yeasts, including Brettanomyces, and bacteria in short periods of time, while retaining the characteristic flavor and aroma of the wine produced. PEF is a promising technology for the beverage industry as it is a continuous process, requiring only microseconds of processing time for the inactivation of undesirable microbes in wines, with commercial scale, higher throughput production potentialinfo:eu-repo/semantics/publishedVersio

Understanding Brettanomyces behaviour to optimise the use of alternatives to SO₂ in wines

Mestrado em Engenharia de Viticultura e Enologia / Instituto Superior de Agronomia. Universidade de LisboaThe wine world is constantly evolving, and the market is increasingly demanding with regard to the characteristics of the final product. Winegrowers must follow the trends that have been emerging in relation to winemaking methods, not only in terms of the final product, but also when talking about all the processes involved in obtaining it. As far as wine defects are concerned, one of the producers' greatest focus is Brettanomyces yeast, which is considered to have the greatest capacity to cause wine spoilage. It has been, in the last decades, a reason for great attention, since it causes great economic losses when the conditions for its establishment in the winery are met, especially when we talk about higher quality red wines that have been submitted to expensive ageing processes in wooden barrels. This yeast has the capacity to produce ethylphenols which, above certain quantities, cause highly undesirable changes in the wine's organoleptic characteristics. To date, the most used and efficient approach to dealing with Brettanomyces is the use of sulphites to prevent its growth. SO₂ is the most widely used additive in wineries for the control of this yeast. However, in recent years there has been growing concern from a number of health and food industry stakeholders about the presence of sulphites in various foods. In addition to the fact that they can be harmful to human health above certain ingested values, there is now an increasing trend towards the reduction of all chemical additives in food. The current trend has led the consumer to prefer all products that are related to organic, sustainable, natural production, words that are increasingly referred to throughout the industry. As a food product, wine has also been following this trend, which is becoming increasingly demanding and challenging. The aim of this review was to analyse most of the available alternative methods to the use of sulphites for the reduction of Brettanomyces in wine, in an attempt to minimise the amount of SO₂ to be added to the final product. Knowing how this yeast behaves, which factors influence its growth and at which stages of the winemaking process it is most likely to develop, are some of the topics. In this way, it is intended to make a synthesis of alternative methods to reduce its incidence, to understand which are the most advantageous and what still has to be done in the future to achieve the desired objectivesN/

Two decades of "Horse sweat" taint and Brettanomyces yeasts in wine: where do we stand now ?

ReviewThe unwanted modification of wine sensory attributes by yeasts of the species Brettanomyces bruxellensis due to the production of volatile phenols is presently the main microbiological threat to red wine quality. The effects of ethylphenols and other metabolites on wine flavor is now recognized worldwide and the object of lively debate. The focus of this review is to provide an update of the present knowledge and practice on the prevention of this problem in the wine industry. Brettanomyces bruxellensis, or its teleomorph, Dekkera bruxellensis, are rarely found in the natural environment and, although frequently isolated from fermenting substrates, their numbers are relatively low when compared with other fermenting species. Despite this rarity, they have long been studied for their unusual metabolical features (e.g., the Custers effect). Rising interest over the last decades is mostly due to volatile phenol production affecting high quality red wines worldwide. The challenges have been dealt with together by researchers and winemakers in an effective way and this has enabled a state where, presently, knowledge and prevention of the problem at the winery level is readily accessible. Today, the main issues have shifted from technological to sensory science concerning the effects of metabolites other than ethylphenols and the over estimation of the detrimental impact by ethylphenols on flavor. Hopefully, these questions will continue to be tackled together by science and industry for the benefit of wine enjoymentinfo:eu-repo/semantics/publishedVersio

Non-thermal high pressure processing, pulsed electric fields and ultrasound preservation of five diffeernt table wines

Wine preservation by alternative non-thermal and physical methods including high pressure processing (HPP), pulsed electric fields (PEF) and power ultrasound (US) technologies was investigated. The effect of these technologies on some quality parameters of five table wines was determined directly after processing and two months storage. For each wine, the pH, colour density, total phenolic content and antioxidant activity quality parameters were determined and the different treatments were compared. The pH of the untreated and treated wines generally remained unchanged after processing and storage. The antioxidant activity of the wines decreased after processing and storage. Generally, non-thermal processing did not affect the wine quality parameters during the 2 months storage. Overall, this study demonstrated that HPP had the smallest effect on the quality parameters assessed in five different winesinfo:eu-repo/semantics/publishedVersio