Influence of the time of bilberry (Vaccinium myrtillus L.) addition on the phenolic and protein profile of beer.

BACKGROUND: In recent years, there has been an increased fruit addition to the brewing process, especially in craft breweries. Fruit addition leads to changes in the organoleptic characteristics and chemical composition of beers. Bilberries are rich in phenolic compounds and possess significant antioxidant capacity. The effects of bilberry addition and brewing process parameters on the changes in the phenolic and protein profile of beer have not been sufficiently studied. The aim of this research was to investigate the changes in the individual phenolic compounds and the protein fractions in beer when bilberries were added at different maturation stages. METHODS: An infusion mashing method was applied for the purpose of obtaining wort with an original extract of 14°P after boiling. Pilsner malt, bitter and aromatic hops 60/40 (Perle and Cascade, respectively), dry yeast Saccharomyces pastorianus (carlsbergensis) Saflager W 34/70, and bilberries (Vaccinium myrtillus L.) were used. All processes were conducted in a Home Brew 50 all-in-one 50 dm3 brewing system. The fermentation was carried out in a stainless steel cylindroconical fermenter at a temperature of 14°C. The “green beer” was transferred to small stainless-steel fermenters after 60% of the original wort extract had been fermented. The maturation continued for 14 days at 14°C, and the beer lagering for 5 days at 2°C. The bilberries were pasteurised in a water bath for 10 minutes at 70°C. After cooling, they were added to small fermenters at a concentration of 167 g/dm3 at the beginning and on the seventh day of beer maturation. All variants were carried out in duplicate. After lagering, the beer was bottled using a “beer gun”. The beer samples from the experiments were filtered on the day of bottling and frozen until analysis. HPLC/UV-VIS and electrophoresis were used to determine the phenolics and proteins, respectively. The total monomeric anthocyanins were determined by the pH differential method. The original wort extract and alcohol concentration were evaluated, and the sensory analysis was performed according to EBC standard methods. RESULTS: The changes in 10 phenolic acids, 7 flavonoids, and 10 protein fractions in beer with bilberries added at the beginning and on the seventh day of maturation were studied. The addition of bilberries led to an increase in the phenolic acid (3-fold) and flavonoid (6.2-fold) concentrations. The highest enrichment was observed in terms of rutin, chlorogenic, caffeic, and 3,4-dihydrobenzoic acids. Rosmarinic acid and monomeric anthocyanins were only detected in the bilberry beers. Chlorogenic and neochlorogenic acids, rutin, and catechin dominated in the bilberry beers. Neochlorogenic and gallic acids, epicatechin, and catechin dominated in the bilberry-free beers. The addition of bilberries reduced the protein content by 93 to 96%. The number of protein fractions decreased from 10 to 4. The influence of the bilberry addition time on the phenolics and proteins was different, and it affected the individual protein fractions in a different way. More phenolic acids and flavonoids were determined when bilberries were added at the beginning of maturation. The losses of some protein fractions were higher at the beginning of maturation and of others on the seventh day of maturation, whereas the addition time did not matter for some of the fractions. CONCLUSIONS: This study provides new information related to the changes in the phenolic and protein profile of beer with bilberries depending on the time of bilberry addition during beer maturation. The protein concentration and number of protein fractions decreased dramatically. In spite of the significant protein losses, the bilberry addition improved the phenolic profile of the beer and its organoleptic characteristics. The presence of more phenolic compounds is related to the antioxidant capacity respective to the biological value of beer. Further research in this direction is needed.

Recent Advances in Research on Polyphenols: Effects on Microbiota, Metabolism, and Health.

Polyphenols have attracted huge interest among researchers of various disciplines because of their numerous biological activities, such as antioxidative, antiinflammatory, antiapoptotic, cancer chemopreventive, anticarcinogenic, and antimicrobial properties, and their promising applications in many fields, mainly in the medical, cosmetics, dietary supplement and food industries. In this review, the latest scientific findings in the research on polyphenols interaction with the microbiome and mitochondria, their metabolism and health beneficial effects, their involvement in cognitive diseases and obesity development, as well as some innovations in their analysis, extraction methods, development of cosmetic formulations and functional food are summarized based on the papers presented at the 13th World Congress on Polyphenol Applications. Future implications of polyphenols in disease prevention and their strategic use as prophylactic measures are specifically addressed. Polyphenols may play a key role in our tomorrow´s food and nutrition to prevent many diseases.

Optimisation of the enzyme-assisted extraction of polyphenols from saffron (Crocus sativus L.) petals.

BACKGROUND: Saffron tepals are a by-product from the processing of Crocus sativus flowers, whose dried stigmas (saffron spice) are widely used both in the food and health sectors. Saffron tepals are rich in polyphenols, particularly flavonol glycosides and anthocyanins, which are considered to be potent antioxidants. Enzyme-assisted extraction of polyphenols offers several advantages in comparison to conventional methods. The present study evaluated the efficiency of enzyme-assisted extraction as a green technology for recovery of polyphenols from saffron tepals. METHODS: The by-product was obtained from a saffron producer in the region of Kozani, Greece. A simplex-centroid design was applied to select the enzyme preparations mixture required for aqueous extraction of polyphenolic antioxidants from dried saffron tepals. In addition, the parameters of enzymatic hydrolysis, enzyme dose and incubation time were optimised using response surface methodology. RESULTS: The binary combination, comprising cellulolytic and hemicellulolytic preparations (1:1), led to the highest yield of total polyphenols (30.9 g GAE/kg saffron tepals) and total anthocyanins (2.0 g CGE/kg saffron tepals), reaching 45% and 38% higher values, respectively, as compared to the control sample (without enzymatic treatment). The experimental data regarding optimisation of the extraction conditions were fitted to second-degree regression models (R2 = 0.85-0.98). CONCLUSIONS: The newly developed process may be applied as an environmentally friendly alternative to conventional organic solvent extraction, thus supporting valorisation of the saffron industry by-product. The polyphenols recovered could be used as biologically active substances or as natural food ingredients, replacing synthetic additives.