1,720,963 research outputs found
Use of Hansensiaspora uvarum and managing growth conditions increase polysaccharides and antioxidants content in yeast autolysates for winemaking
Full text linkYeast derivatives are winemaking additives generally obtained from Saccharomyces spp., commonly used as fermentation and wine quality enhancers. Even though they are widely used, the production process - from initial biomass to their final composition, is not standardized and often not specific for winemaking purposes. In the present study, biomass production was performed by applying different temperatures and agitation conditions, to assess their effect on the chemical composition of the resulting derivatives, using S. cerevisiae and H. uvarum as starting microorganisms. The application of shaking mostly affected the chemical composition of yeast derivatives, resulting in the highest mean concentration of amino acids (146 mg/g in S. cerevisiae), polysaccharides (370 mg/g in H. uvarum), and glutathione (about 85 μmol/g in S. cerevisiae). Derivatives obtained from H. uvarum were characterized by a non-negligible amount of glutathione (35.6 μmol/g - 53.1 μmol/g) and cysteine (12.7 μmol/g - 26.2 μmol/g), regardless of the growth conditions previously applied; only for this strain, reducing proteins linked to cell wall residues were detected. The results obtained suggest that the chemical composition of yeast derivatives may be managed during biomass production, also using specific strains, thus possibly obtaining products naturally rich in compounds of enological interest
Use of olive (Olea europaea L.) leaves as beer ingredient, and their influence on beer chemical composition and antioxidant activity
No full textAbstract: Olive leaves are well known for their high polyphenol content and beneficial effects to human health. The two main phenolic compounds of olive leaves are oleuropein and 3-hydroxytyrosol. Use of olive leaves as beer ingredient was evaluated, to investigate their contribution to bitterness and antioxidant activity of beer. Thirteen beer samples were produced, adding olive leaves during boiling at different boiling times, in different forms and concentrations. Three different forms were used: dry crumbled leaves, infusion, and atomized extract. The effects of olive leaves addition were evaluated through following analysis: total polyphenols content, oleuropein and 3-hydroxytyrosol content, antioxidant capacity, sensory analysis, shelf-life prediction. Results confirmed that addition of olive leaves highly increased polyphenol content of beers. Boiling time favored hydrolysis of oleuropein to 3-hydroxytyrosol. Antioxidant activity was not influenced by addition of olive leaves. Higher polyphenol content of beer samples increased colloidal instability of beer. Sensory analysis results demonstrated that about 10 g/L of olive leaves imparts a sour/astringent taste and herbal aroma. A lower quantity of olive leaves (about 5 g/L) allowed to obtain a beer with a pleasant sensory profile. Practical Application: Our research was inspired by both the high interest in alternative ingredients able to add nutraceutical value to traditional food, and by the growing craft beer market, with its constant research for innovative and characterizing ingredients. This project has several aims: evaluate if olive leaves could partially substitute hops in beer bittering (reducing costs); if their addition increase beer polyphenol content; which amount and using technique gives the best results in terms of polyphenol extraction and sensory profile; how this addition influence beer stability. This work could then encourage new research about the nutraceutical value of this new type of beer
Industrial beer versus craft beer: Definitions and nuances
No full textThis chapter defines the concepts of industrial and craft beers and provides the reader with information on industrial versus craft beer’s characteristics (e.g., raw materials, brewing processes, stabilization, attributes, and flavor of industrial beer and craft beer). It also illustrates the new potentialities of the beer market related to the growing popularity of craft beer. The evolution of the market is shown in terms of product differentiation driven by both demand and supply
Use of Friulan saffron in the production of craft beer
No full textSaffron (Crocus sativus L.) is the most expensive spice in the world. Saffron is costly due to the meagre yield per acre and exorbitant manpower costs. The three key compounds in saffron are crocin, picrocrocin and safranal, which are responsible for its colour, bitterness and flavour, respectively. The aim of this study was to exploit the bittering, aromatic and colouring properties of saffron to formulate a craft beer with refined taste and colour. As a result of the elevated price of the raw material, the saffron extraction process was optimised to achieve the best results using as little spice as possible. Thus, the extraction yields of two different methods were ascertained. To assess the ideal concentration of saffron to obtain a beverage with a balanced taste, three beers containing increasing concentrations of the spice were brewed. Then, once a sensory test was performed, another three samples were produced with the minimum dose of the spice (50 mg/L), added at various times during the production process (at 5 and 20 min before the end of the boiling stage, during the whirlpool stage and during refermentation). The purpose was to evaluate the consequences of heat treatment on crocin, picrocrocin and safranal compounds provided to the beer. All of the beer samples underwent routine analyses (alcoholic strength, Plato, IBU, colour and pH) and were analysed by spectrophotometry
Dip Hopping Technique and Yeast Biotransformations in Craft Beer Productions
Full text linkThis paper evaluates the effects of an alternative hopping technique, called dip hopping, on beer. This technique involves infusing hops in hot water (or in a portion of wort) and subsequently combining the infusion with the wort (after wort cooling) directly in the fermenter when the yeast is added for fermentation. The reference beers were produced employing the “traditional” late hopping technique, and the experimental beers were produced using the dip hopping technique. A variety of hops with a significant concentration of essential oil and a strain of yeast with high β-glucosidic activity capable of releasing aromatic molecules from precursors supplied by hops were used. The samples were analysed in terms of alcohol content, degree of attenuation, colour, and bitterness. Sensory analysis and gas chromatography analysis were also performed. The data showed statistically significant differences between the reference beers and the experimental beers, with the latter featuring greater hints of citrus, fruity, floral, and spicy aromas. As an overall effect, there was an increase in the olfactory and gustatory pleasantness of the beers produced with the dip hopping technique
Biotransformations Performed by Yeasts on Aromatic Compounds Provided by Hop—A Review
Full text linkThe biodiversity of some Saccharomyces (S.) strains for fermentative activity and metabolic capacities is an important research area in brewing technology. Yeast metabolism can render simple beers very elaborate. In this review, we examine much research addressed to the study of how different yeast strains can influence aroma by chemically interacting with specific aromatic compounds (mainly terpenes) from the hop. These reactions are commonly referred to as biotransformations. Exploiting biotransformations to increase the product’s aroma and use less hop goes exactly in the direction of higher sustainability of the brewing process, as the hop generally represents the highest part of the raw materials cost, and its reduction allows to diminish its environmental impact
Monitoring of some selected heavy metals throughout the brewing process of craft beers by inductively coupled plasma mass spectrometry
No full textHerbicides, fungicides and bactericides containing
heavy metals used in agriculture make it possible
to find these toxic metals in beer (Čejka et al. in Ecol
Chem Eng S 18:67–74, 2011). The aim of this work was to
monitor the distribution of some toxic heavy metals such
as cadmium (Cd), chromium (Cr), copper (Cu), nickel
(Ni), lead (Pb) zinc (Zn), iron (Fe) and arsenic (As) during
craft beers production (three types of beer produced in
four different breweries). The instrumental method adopted
in this investigation was inductively coupled plasma mass
spectrometry. The collected results demonstrated how a
very low (μg/L) heavy metal contamination (mainly Cr, Zn
and Cu) was provided by raw materials (water, malt, hops
and yeasts) and that these toxic metals mostly pass into the
residuals (spent grains, hot trub and yeasts), so only a negligible
fraction of them can be detected in beer. For example,
treating hops with a high dose of pesticides containing Cu
did not cause an increase in its content in final beer because
a large part of copper remains in hot trub. Furthermore, the
filtration phase caused the increase in the concentration of
Cd, Zn, Fe and As, probably due to the use of filtration aids.
These increases were insignificant healthwise [http://www.
edqm.eu/en/Metals-and-alloys-used-in-food-contact-materials-
and-articles-1st-Edition-(CouncilofEurope,2002)].
The craft beers produced without the final filtration did not present this increase. Pb and Ni were always found below
the detection limits
Intensification of grape marc (Vitis vinifera) exploitation by subcritical water-ethanol extraction: Effect on polyphenol bioactivities and kinetic modelling
Full text linkSubcritical solvent extraction (SSE) is an efficient and versatile technology for the recovery of bioactive compounds from food by-products. The present work aims to study the SSE efficiency and kinetics for the extraction of grape marc polyphenols. Water, ethanol, and a 50% water-ethanol mixture (EtOH 50%) were used as green solvents. The higher polyphenol content (4.05 ± 0.23 gGAE/100 gd. m.) and antioxidant activity (42.30 ± 0.68 mg α-toc/mL) were obtained with subcritical EtOH 50% at 120 °C and 10.3 MPa, respectively, 1.5- and 3-fold higher than the conventional extraction. According to kinetic modeling, SSE was four-fold faster and a degradation phenomenon of polyphenols was highlighted for times longer than 10 min. The two-site kinetic model and a second order exponential decay function suitably described the extraction kinetics and degradation phase, respectively (R2 > 0.97). A remarkable effect was highlighted on the polymerization degree and galloylation percentage of proanthocyanidins by SSE, and an increase in their antioxidant activity was observed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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