Non-conventional yeasts from fermented honey by-products: Focus on Hanseniaspora uvarum strains for craft beer production.

The increasing interest in novel beer productions focused on non-Saccharomyces yeasts in order to pursue their potential in generating groundbreaking sensory profiles. Traditional fermented beverages represent an important source of yeast strains which could express interesting features during brewing. A total of 404 yeasts were isolated from fermented honey by-products and identified as Saccharomyces cerevisiae, Wickerhamomyces anomalus, Zygosaccharomyces bailii, Zygosaccharomyces rouxii and Hanseniaspora uvarum. Five H. uvarum strains were screened for their brewing capability. Interestingly, Hanseniaspora uvarum strains showed growth in presence of ethanol and hop and a more rapid growth than the control strain S. cerevisiae US-05. Even though all strains showed a very low fermentation power, their concentrations ranged between 7 and 8 Log cycles during fermentation. The statistical analyses showed significant differences among the strains and underlined the ability of YGA2 and YGA34 to grow rapidly in presence of ethanol and hop. The strain YGA34 showed the best technological properties and was selected for beer production. Its presence in mixed- and sequential-culture fermentations with US-05 did not influence attenuation and ethanol concentration but had a significant impact on glycerol and acetic acid concentrations, with a higher sensory complexity and intensity, representing promising co-starters during craft beer production.

Sourdough cultures as reservoirs of maltose-negative yeasts for low-alcohol beer brewing.

De novo sourdough cultures were here assessed for their potential as sources of yeast strains for low-alcohol beer brewing. NGS analysis revealed an abundance of ascomycete yeasts, with some influence of grain type on fungal community composition. Ten different ascomycete yeast species were isolated from different sourdough types (including wheat, rye, and barley) and seven of these were screened for a number of brewing-relevant phenotypes. All seven were maltose-negative and produced less than 1% (v/v) alcohol from a 12 °Plato wort in initial fermentation trials. Strains were further screened for their bioflavouring potential (production of volatile aromas and phenolic notes, reduction of wort aldehydes), stress tolerance (temperature extremes, osmotic stress and ethanol tolerance) and flocculence. Based on these criteria, two species (Kazachstania servazzii and Pichia fermentans) were selected for 10 L-scale fermentation trials and sensory analysis of beers. The latter species was considered particularly suitable for production of low-alcohol wheat beers due to its production of the spice/clove aroma 4-vinylguaiacol, while the former showed potential for lager-style beers due to its clean flavour profile and tolerance to low temperature conditions.

Influence of malt composition on the quality of a top fermented beer.

The beer is a widely consumed drink, appreciated for its sensory characteristics, and it also contains beneficial compounds for health derived from its raw materials. In this work, the influence of coloured malt on the main quality parameters of a top-fermenting beer was evaluated. The beers were produced increasing the percentage of coloured malt (0, 5, 15% Caraamber®) respect to the pale ale base malt. The beers had an alcohol content ranging from 6.2 to 6.8 vol%; the results highlighted a deeper colour, increased bitterness and turbidity in beer with the highest amount of Caraamber malt. This latter showed the highest polyphenols (453.8 mg GAE/L) and antioxidant activity (840.1 µmol TE/L) and, on the other hand, the lowest foam stability. The volatiles profile showed a higher amount of aldehydes and ketones in beer with the highest percentage of caramel malt but the lowest in higher alcohols and esters. No differences were found in the fruity-esters, alcoholic and caramel sensory notes; while the beer made with 15% of coloured malt was perceived sweeter and with less fruity citrus notes than other beer samples.

Influence of the dealcoholisation by osmotic distillation on the sensory properties of different beer types.

A comparative study was performed to better understand the feasibility of osmotic distillation as a process to produce a low-alcohol beer. Four diverse commercial beers styles were considered. The regular and corresponding dealcoholised beers were compared. The quality attributes and the volatile compounds loss after the dealcoholisation were checked. The work focused on the sensory properties of the obtained samples. A trained panel evaluated how the chosen sensory descriptors were influenced by the treatment. The results of quality attributes and volatile compounds were in line with works previously published by the authors. Interestingly, the results highlighted that beer characterized by malty character is more suitable than pale lager to be dealcoholised by the osmotic distillation process. The low alcohol milk stout and stout flavour profile, especially in terms of taste, was like the corresponding regular beer. Osmotic distillation was demonstrated to be a feasible process to produce low-alcohol beer.

Rice malting optimization for the production of top-fermented gluten-free beer.

BACKGROUND: A safe method to obtain gluten-free beer led to the use of naturally gluten-free grains, such as rice, but the specific malting program for rice is long and requires a large amount of water, and the resulting beer showed a flat flavour profile. In this study, an optimization of the malting and brewing procedure is proposed to overcome the aforementioned issues. Different steeping conditions and kilning temperatures are considered, and a top-fermented beverage from rice malt is obtained for the first time. RESULTS: The malting procedure has been optimized by assessing the use of short-time steeping as an alternate to long air rest to obtain sufficient moisture content in the green malt, saving water consumption. The malt obtained allowed a regular fermentation, as confirmed by the sensorial analysis, which did not reveal any off-flavours. The use of a top-fermenting yeast formed high content of higher alcohol and relatively low amount of esters. CONCLUSION: This study confirms the potential of rice for the production of malt and beer. The optimized malting programme allowed water saving. The production of a top-fermented rice malt beer was a successful attempt to introduce a new flavoured product for consumption by individuals affected by coeliac disease. © 2018 Society of Chemical Industry.

Germination under Moderate Salinity Increases Phenolic Content and Antioxidant Activity in Rapeseed (Brassica napus var oleifera Del.) Sprouts.

The use of sprouts in the human diet is becoming more and more widespread because they are tasty and high in bioactive compounds and antioxidants, with related health benefits. In this work, we sprouted rapeseed under increasing salinity to investigate the effect on free and bound total phenolics (TP), non-flavonoids (NF), tannins (TAN), phenolic acids (PAs), and antioxidant activity. Seeds were incubated at 0, 25, 50, 100, 200 mM NaCl until early or late sprout stage, i.e., before or after cotyledon expansion, respectively. Sprouting and increasing salinity slightly decreased the bound fractions of TP, NF, TAN, PAs, while it increased markedly the free ones and their antioxidant activity. Further increases were observed in late sprouts. Moderate salinity (25-50 mM NaCl) caused the highest relative increase in phenolic concentration while it slightly affected sprout growth. On the contrary, at higher NaCl concentrations, sprouts grew slowly (100 mM NaCl) or even died before reaching the late sprout stage (200 mM). Overall, moderate salinity was the best compromise to increase phenolic content of rapeseed sprouts. The technique may be evaluated for transfer to other species as a cheap and feasible way to increase the nutritional value of sprouts.

Antioxidant effects of supercritical fluid garlic extracts in sunflower oil.

BACKGROUND: Lipid oxidation causes changes in quality attributes of vegetable oils. Synthetic antioxidants have been used to preserve oils; however, there is interest in replacing them with natural ones. Garlic and its thiosulfinate compound allicin are known for their antioxidant activities. This study assesses a novel formulation, the supercritical fluid extract of garlic, on sunflower oil oxidation during an accelerated shelf-life test. RESULTS: Three quality parameters (free acidity, peroxide values, and p-anisidine values) were evaluated in each of the six oil samples. The samples included sunflower oil alone, sunflower oil supplemented with BHT, the undiluted supercritical fluid extract of garlic, and sunflower oils supplemented with three levels of garlic extract. The oils were also investigated for their antioxidant properties using the DPPH and the FRAP assays. The results were compared with the effect of the synthetic BHT. Our results underlined that the highest level of garlic extract may be superior, or at least comparable, with BHT in preserving sunflower oil. CONCLUSION: The oxidative degradation of oily samples can be limited by using supercritical fluid extract of garlic as it is a safe and an effective natural antioxidant formulation. © 2016 Society of Chemical Industry.

Influence of yeast strain, priming solution and temperature on beer bottle conditioning.

BACKGROUND: Recently, there has been a significant increase in the number of microbreweries. Usually, craft beers are bottle conditioned; however, few studies have investigated beer refermentation. One of the objectives of this study was to evaluate the impacts of different experimental conditions, specifically yeast strain, priming solution and temperature, on the standard quality attributes, the volatile compounds and the sensory profile of the bottle-conditioned beer. The other aim was to monitor the evolution of volatile compounds and amino acids consumption throughout the refermentation process to check if it is possible to reduce the time necessary for bottle conditioning. RESULTS: The results indicate that the volatile profile was mainly influenced by the strain of yeast, and this may have obscured the possible impacts of the other parameters. Our results also confirm that the two yeast strains showed different metabolic activity, particularly with respect to esters production. Moreover, we found the Safbrew S-33® strain when primed with Siromix® and refermented at 30 °C yielded the fastest formation of higher alcohols while maintaining low production of off-flavours. CONCLUSIONS: These results suggest a formulation that may reduce the time needed for bottle conditioning without affecting the quality of the final beer which may simultaneously improve efficiency and economic profits. © 2016 Society of Chemical Industry.

Near-infrared Spectroscopy in the Brewing Industry.

This article offers an exhaustive description of the use of Near-Infrared (NIR) Spectroscopy in the brewing industry. This technique is widely used for quality control testing of raw materials, intermediates, and finished products, as well as process monitoring during malting and brewing. In particular, most of the reviewed works focus on the assessment of barley properties, aimed at quickly selecting the best barley varieties in order to produce a high-quality malt leading to high-quality beer. Various works concerning the use of NIR in the evaluation of raw materials, such as barley, malt, hop, and yeast, are also summarized here. The implementation of NIR sensors for the control of malting and brewing processes is also highlighted, as well as the use of NIR for quality assessment of the final product.

Characterization of the volatile profiles of beer using headspace solid-phase microextraction and gas chromatography-mass spectrometry.

BACKGROUND: The objective of this study was a multivariate characterization of the volatile profile of beers. Such a characterization is timely considering the increasing worldwide consumption of beer, the continuous growth of microbreweries and the importance of volatile compounds to beer flavour. A method employing solid-phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS) was optimized and then applied to a sample set of 36 industrial and craft beers of various styles and fermentation types. RESULTS: The volatile profiles of different beer styles is described, with particular attention paid to the volatile compounds characteristic of a spontaneously fermented lambic raspberry framboise beer. Furthermore, it was also possible to identify which specific volatile compounds are principally responsible for the differences in the volatile profiles of top- and bottom-fermented beers. Moreover, a volatile fingerprint of the craft top-fermented Italian beers was defined, as they show a very similar volatile profile. Finally, the volatile compounds that are characteristic of the bock-style beers are described. CONCLUSIONS: The SPME-GC-MS analytical method optimized in this study is suitable for characterizing the volatile fingerprint of different beers, especially on the basis of the kind of fermentation (top, bottom or spontaneous), the method of production and the style of the beer.

Phenolic compounds from pumpkin pulp: Extraction optimization and biological properties.

Ultrasound-assisted extraction of (poly)phenols from pumpkin pulp was optimized using response surface methodology. Time, solvent-to-sample ratio and percentage of water in ethanol were considered and a full factorial design was applied. The optimized conditions (10 min; 30 mL/g; 50% water in ethanol) were used to isolate (poly)phenols from five pumpkin varieties (Hokkaido, Lunga di Napoli, Mantovana, Moscata di Provenza, Violina rugosa), collected for two successive years. Phenolic acids were the most abundant phenolic class (gallic acid up to 413.50 µg/g), even if differences were observed among varieties and harvesting years. Generally, Violina rugosa harvested in 2021 showed the highest total phenol content (7.59 mg gallic acid equivalents/g) and antioxidant properties (16.93 mg Trolox equivalents/g). All pumpkin variety exhibited antimicrobial activity within a concentration range of 1.95 to 250 µg/mL. In conclusion, the pumpkin pulp can be considered a promising natural source of (poly)phenols for the development of health-promoting products.

Development of gluten-free craft beer: Impact of brewing process on quality attributes and consumer expectations for sensory properties.

To date, few studies investigated the differences between the two main gluten-free (GF) brewing techniques, such as the use of enzymes and the use of unconventional GF grains in brewing, by consumer perspective. In this study a GF beer brewed with sorghum and quinoa, as brewing adjuncts, was compared to the enzymatic-treated counterpart, in order to evaluate the effect of deglutinization treatment on physicochemical, volatile, and sensory characteristics of final beer. Moreover, the influence of brewing process and raw materials information on consumers' sensory perceptions, willingness to buy (WTB) and willingness to pay (WTP) was also investigated (n = 105 consumers), under blind (B), expected (E), and informed (I) conditions. The enzymatic-treated sample showed comparable physicochemical attributes with the untreated counterpart, except for a significant reduction in color and foam stability (p < 0.05). Non-significant difference between samples was found in the overall liking, WTB, and WTP mean scores in all three sensory test conditions (p > 0.05). The information about the deglutinization treatment had a negative impact on overall liking (p < 0.01), although WTP for both samples was significantly higher in the informed test than in blind condition (p < 0.05). Overall, Check-All-That-Apply test results confirmed that the deglutinization treatment does not affect the beer sensory profile, even if the information about brewing ingredients and technologies may slightly influence the consumers' sensory perception. Therefore, this result proves that it is possible to produce a marketable GF beer, simply by partially replacing 40% of barley malt with unconventional GF grains, without using enzymes for gluten reduction purpose.

Assessment of brewing attitude of unmalted cereals and pseudocereals for gluten free beer production.

In this study, 40% of unmalted gluten free (GF) grains (sorghum, millet, buckwheat, quinoa and amaranth) was used in brewing process, in gelatinized and ungelatinized form, in order to produce GF beer and to extend current knowledge about their suitability as brewing adjuncts. Partial replacement of barley malt with GF grains led to a significant decrease of extract (°P) and alcohol (%v/v) content compared to control beer (p < 0.05), except for quinoa beer (QB). Results from Principal Component Analysis (PCA) highlighted a satisfactory classification of experimental beers according to the two different forms of GF grains (gelatinized and ungelatinized). However, beers brewed with ungelatinized grains (mainly sorghum and quinoa) showed acceptable technological and sensory properties, thus suggesting that the pre-gelatinization step could be bypassed with a view to more environmentally and economically sustainable time-saving process. In addition, all beer samples showed a gluten content higher than 20 ppm.

Secoisolariciresinol diglucoside determination in flaxseed (Linum usitatissimum L.) oil and application to a shelf life study.

A high-performance liquid chromatographic (HPLC) reliable and sensitive method with diode array detection (DAD) system has been developed for the determination of secoisolariciresinol diglucoside (SDG) in flaxseed oil. An analytical methodology based on the sample extraction with methanol/water (80:20, v/v), subsequent purification of the sample and analysis of the extract by HPLC/DAD is proposed for the determination of SDG in flaxseed oil. The coefficient of determination of the standard calibration curve was 0.999, the limit of detection was 0.08µg/mL, and the limit of quantification was 0.27µg/mL. The recovery test was conducted adding four different concentrations of standard solution to the blank sample. The recovery ranged from 90% to 95%. To our knowledge, the presence and quantification of SDG in flaxseed oil has never been reported. The proposed method was tested to study the variation in SDG content in flaxseed oil during a shelf-life test to verify its applicability in quality control for oil industries. The dark and the low temperature of storing together allowed to preserve SDG. A slight pro-oxidant effect was observed for the addition of antioxidant to the flaxseed oil.

Influence of barley variety, timing of nitrogen fertilisation and sunn pest infestation on malting and brewing.

BACKGROUND: This paper presents a multivariate approach to investigate the influence of barley variety, timing of nitrogen fertilisation and sunn pest infestation on malting and brewing. Four spring and two winter barley varieties were grown in one location in southern Europe. Moreover, one of the spring varieties was infested with sunn pest, in order to study the effects of this pest on malting quality, and subjected to different nitrogen fertilisation timing regimes. The samples were micromalted, mashed, brewed and analysed. RESULTS: The data showed that even though the two winter barleys seemed to be the best regarding their physical appearance (sieving fraction I + II > 82%), this superiority was not confirmed in the malt samples, which showed low values of Hartong extract (27.1%) and high values of pH (6.07-6.11) and ß-glucan content (12.5-13.2 g kg(-1)), resulting in low-quality beers. The barley sample subjected to postponed fertilisation had a total nitrogen content (19.5 g kg(-1) dry matter) exceeding the specification for malting barley and gave a beer with a low content of free amino nitrogen (47 mg L(-1)) and high values of viscosity (1.99 cP) and ß-glucan content (533 mg L(-1)). The beer obtained from the barley sample subjected to pest attack had good quality parameters. CONCLUSION: All spring barleys gave well-modified malts and consequently beers of higher quality than the winter barleys. Moreover, postponed fertilisation was negatively related to the quality of the final beer, and sunn pest infestation did not induce important economic losses in the beer production chain.

Brewing By-Product Upcycling Potential: Nutritionally Valuable Compounds and Antioxidant Activity Evaluation.

The brewing industry produces high quantities of solid and liquid waste, causing disposal issues. Brewing spent grains (BSGs) and brewing spent hop (BSH) are important by-products of the brewing industry and possess a high-value chemical composition. In this study, BSG and BSH, obtained from the production process of two different types of ale beer (Imperial red and Belgian strong beer) were characterized in terms of valuable components, including proteins, carbohydrates, fat, dietary fiber, ß-glucans, arabinoxylans, polyphenols, and phenolic acids, and antioxidant activity (Ferric Reducing Antioxidant Power Assay (FRAP), 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS)). Significant concentrations of total polyphenols were observed in both BSH and BSG samples (average of about 10 mg GAE/g of dry mass); however, about 1.5-fold higher levels were detected in by-products of Belgian strong ale beer compared with Imperial red. Free and bound phenolic acids were quantified using a validated chromatographic method. A much higher level of total phenolic acids (TPA) (about 16-fold higher) was found in BSG samples compared with BSHs. Finally, their antioxidant potential was verified. By-products of Belgian strong ale beer, both BSG and BSH, showed significantly higher antioxidative capacity (about 1.5-fold lower inhibitory concentration (IC50) values) compared with spent grains and hop from the brewing of Imperial red ale. In summary, BSG and BSH may be considered rich sources of protein, carbohydrates, fiber, and antioxidant compounds (polyphenols), and have the potential to be upcycled by transformation into value-added products.

High genetic and chemical diversity of wild hop populations from Central Italy with signals of a genetic structure influenced by both sexual and asexual reproduction.

In order to investigate the intraspecific diversity of wild Humulus lupulus (hop) in Central Italy, 12 populations were evaluated for their genetic polymorphism by means of 13 SSR loci together with six commercial cultivars as a reference. High levels of polymorphism were found across the populations, being 140 the number of multilocus genotypes over 159 samples analyzed. Moreover, the observed heterozygosity was higher than expected in most of the populations. High levels of gene flow were thus envisaged to occur within and among wild populations, and our sampling strategy allowed us to gain insights on the propagation modes of this species, i.e. clonal versus sexual propagation. Nevertheless, a genetic structure of populations with at least five genetically different clusters was disclosed. Private alleles were observed in both wild and cultivated hops. Chemical analysis of bittering and aromatic quality of female flowers from a subset of 8 wild populations revealed a high variability among plants, especially for essential oil components. Overall, the high variability of wild accessions here examined represent a valid source to be exploited in future breeding programs for new or improved hop cultivars development.

Comparison of carbohydrate partitioning and expression patterns of some genes involved in carbohydrate biosynthesis pathways in annual and biennial species of Cichorium spp.

Variation in metabolism and partitioning of carbohydrates, particularly fructans, between annual and perennial Cichorium species remains a challenging topic. To address this problem, an annual (endive, Cichorium endive L. var. Crispum; Asteraceae) and a biennial species (chicory, Cichorium intybus L. var. Witloof; Asteraceae) were compared with in terms of variability in carbohydrate accumulation and expression patterns of fructan-active enzyme genes, as well as sucrose metabolism at various growth and developmental stages. In general, constituents such as 1-kestose, nystose, and inulin were detected only in the root of chicory and were not present in any of the endive tissues. For both species, flower tissue contained maximum levels of both fructose and glucose, while for sucrose, more fluctuations were observed. On the other hand, all the genes under study exhibited variation, not only between the two species but also among different tissues at different sampling times. In endive root compared to endive leaf, the expression of cell wall invertase genes and sucrose accumulation decreased simultaneously, indicating the limited capacity of its roots to absorb sucrose, a precursor to inulin production. In addition, low expression of fructan: fructan fructosyltransferase in endive root compared to chicory root confirmed the inability of endive to inulin synthesis. Overall, annual and biennial species were different in the production of inulin, transport, remobilization, and unloading of sucrose.

Accelerated shelf-life model of gluten-free rusks by using oxidation indices.

The demand for gluten-free products has been growing over the last few years as is the need to improve their quality. The objective of this research was to develop a shelf life prediction model of gluten-free rusks. To this aim, a kinetic study of the primary and secondary oxidative process was run and the kinetic parameters (rate constant, activation energy, and temperature quotient) were calculated. The protective effect of the antioxidant included in the recipe was also evaluated, and the prediction model was applied to predict the shelf life of an experimental batch of gluten-free rusks with a lower content of antioxidant. The results highlighted (i) the reliability of the prediction model and (ii) the effectiveness of the antioxidant in reducing the rate of primary oxidation. Moreover, (iii) a possible hexanal threshold (lower than 121 µg/kg), correlated with rancid perception in gluten-free rusks, was also speculated.

Effect of Addition of Different Phenolic-Rich Extracts on Beer Flavour Stability.

Flavour stability is a key factor in the beer production process. The stabilizing effect of six commercial phenolic-rich extracts was studied. The extracts were added to beer before bottling. Quality parameters (colour, turbidity, foam and dissolved oxygen content), antioxidant activity by 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), total polyphenols content, and sensorial analysis by a trained panel were performed over the course of storage. The beers were analyzed every 3 months for a total period of 6 months. Results indicated that all studied phenolic-rich extracts positively affected the beer flavour stability. In particular, the condensed tannins showed a significant protective effect. The condensed green tea tannins resulted as the most promising source of natural antioxidant able to prolong beer shelf-life and bring interesting organoleptic characteristics to beer. Also, grape seed tannins appeared suitable to boost flavour stability and improve organoleptic properties of beer.