Among the most important factors influencing beer quality is the presence of well-adjusted amounts of higher alcohols and esters. Thus, a heavy body of literature focuses on these substances and on the parameters influencing their production by the brewing yeast. Additionally, the complex metabolic pathways involved in their synthesis require special attention. More than a century of data, mainly in genetic and proteomic fields, has built up enough information to describe in detail each step in the pathway for the synthesis of higher alcohols and their esters, but there is still place for more. Higher alcohols are formed either by anabolism or catabolism (Ehrlich pathway) of amino acids. Esters are formed by enzymatic condensation of organic acids and alcohols. The current paper reviews the up-to-date knowledge in the pathways involving the synthesis of higher alcohols and esters by brewing yeasts. Fermentation parameters affecting yeast response during biosynthesis of these aromatic substances are also fully reviewed.

/pdf/yeast-the-soul-of-beer-s-aroma-a-review-of-flavour-active-1hxlpt5om4.pdf

Yeast: the soul of beer’s aroma—a review of flavour-active esters and higher alcohols produced by the brewing yeast

The invention relates, inter alia, to a DNA construct comprising a DNA sequence which encodes an enzyme exhibiting lipolytic activity and which comprises: a) the DNA sequence shown in SEQ ID No. 1, or b) an analogue of the DNA sequence shown in SEQ ID No. 1 which i) is homologous with the DNA sequence shown in SEQ ID No. 1, and/or ii) hybridizes with the same oligonucleotide probe as the DNA sequence shown in SEQ ID No. 1, and/or iii) encodes a polypeptide which is homologous with the polypeptide encoded by a DNA sequence comprising the DNA sequence shown in SEQ ID No. 1, and/or iv) encodes a polypeptide which is immunologically reactive with an antibody raised against a purified lipolytic enzyme which is encoded by the DNA sequence shown in SEQ ID No. 1 and/or which is derived from Humicola insolens DSM 1800. Also disclosed, inter alia, are: lipolytic enzymes encoded by such DNA constructs; and enzyme preparations, detergent additives and detergent compositions comprising such lipolytic enzymes.

An enzyme with lipolytic activity

Pectin represents a very heterogeneous biopolymer whose functionality remains largely puzzling. The link between the pectin fine structure and functional properties with relevance to plant growth and development, as well as food processing, is continually being explored. This review describes the current knowledge of pectin structure–function relationships. Key mechanisms dictating pectin structure–function relationships are discussed, including the polymer biosynthesis, cross-linking mechanisms, enzymatic and nonenzymatic conversion reactions, solubility properties, and more. Insight into the polymer structure–function relationships is highlighted by examining traditional and advanced methodologies used in pectin research. The role of pectin in modulating the quality characteristics of plant-based foods is underlined while pin-pointing some of the main challenges and perspectives. An integrated approach using the pectin structure–function relationship in the precision engineering of mechanical properties of tissue-based systems is proposed.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1541-4337.2009.00071.x

Pectins in Processed Fruits and Vegetables: Part II—Structure–Function Relationships

Biomass is pretreated using a low concentration of aqueous ammonia at high biomass concentration. Pretreated biomass is further hydrolyzed with a saccharification enzyme consortium. Fermentable sugars released by saccharification may be utilized for the production of target chemicals by fermentation.

Treatment of biomass to obtain fermentable sugars

An enzyme composition with substantial cellulolytic, especially endoglucanase, activity at alkaline conditions which is derived from or producible by fungi from the genus Acremonium, provided that the enzyme composition is not immunologically cross-reactive with antibodies raised against endoglucanases (EC 3.2.1.4) from Humicola insolens, DSM 1800, Fusarium oxysporum, DSM 2672, Myceliophthora thermophila, CBS 117.65, or Cephalosporium sp., RYM-202. The invention further relates to a DNA construct comprising a DNA sequence encoding an enzyme exhibiting endoglucanase activity. The enzyme composition and the isolated or cloned and expressed cellulase of the invention may be useful in any industrial process requiring an alkaline cellulase, e.g. for providing localised variation in the colour density of dyed fabric such as stone-washing of denim, for improving the drainage of an aqueous suspension of paper pulp, for the de-inking of recycled paper, in detergent compositions and in fabric softeners.

An enzyme and enzyme preparation with endoglucanase activity

An enzyme exhibiting xylanase activity, which enzyme is immunologically reactive with an antibody raised against a purified xylanase derived from Aspergillus aculeatus, CBS 101.43. The enzyme may be used for degrading plant cell wall components e.g. in the preparation of feed, in baking, in the paper and pulp industry and in connection with separation of wheat into starch and gluten.

Enzymes with xylanase activity from aspergillus aculeatus

High-gravity brewing, which can decrease production costs by increasing brewery yields, has become an attractive alternative to traditional brewing methods. However, as higher sugar concentration is required, the yeast is exposed to various stresses during fermentation. We evaluated the influence of high-gravity brewing on the fermentation performance of the brewer’s yeast under model brewing conditions. The lager brewer’s strain Weihenstephan 34/70 strain was characterized at three different gravities by adding either glucose or maltose syrups to the basic wort. We observed that increased gravity resulted in a lower specific growth rate, a longer lag phase before initiation of ethanol production, incomplete sugar utilization, and an increase in the concentrations of ethyl acetate and isoamyl acetate in the final beer. Increasing the gravity by adding maltose syrup as opposed to glucose syrup resulted in more balanced fermentation performance in terms of higher cell numbers, respectively, higher wort fermentability and a more favorable flavor profile of the final beer. Our study underlines the effects of the various stress factors on brewer’s yeast metabolism and the influence of the type of sugar syrups on the fermentation performance and the flavor profile of the final beer.

Physiological characterization of brewer's yeast in high-gravity beer fermentations with glucose or maltose syrups as adjuncts.

The formation of acrylamide during heat treatment in the production of a food product is reduced by treating the raw material with an enzyme before the heat treatment. The enzyme is capable of reacting on asparagine or glutamine (optionally substituted) as a substrate or is a laccase or a peroxidase.

Method of preparing a heat-treated product

Method of screening for a DNA sequence coding for a protein of interest, the method comprising a) cloning, in suitable vectors, a DNA library from an organism suspected of producing one or more proteins of interest; b) transforming suitable yeast host cells with said vectors; c) culturing the host cells under suitable conditions to express any protein of interest encoded by a clone in the DNA library, and d) screening for positive clones by determining any activity of a protein expressed in step (c). An enzyme which exhibits cellulase activity and has been isolated from DNA library of Humicola insolens. The enzyme has a cellulose binding domain and exhibits endocellulase activity in the presence of linear alkyl benzene sulfonate.

A method of cloning proteins in yeast and cellulase from humicola insolens

The xylanase is characterized by several partial amino acid sequences and is immunoreactive with an antibody raised against a purified xylanase derived from Humicola insolens, DSM 1800. This xylanase preparation is practically free of cellulase and is well suited for treatment of paper pulp, as a baking agent and as an additive to fodder.

Hans Peter Heldt-Hansen

Papers

Enzymes with xylanase activity from aspergillus aculeatus

Physiological characterization of brewer's yeast in high-gravity beer fermentations with glucose or maltose syrups as adjuncts.

Method of preparing a heat-treated product

A method of cloning proteins in yeast and cellulase from humicola insolens

Xylanase, corresponding recombinant dna sequence, xylanase containing agent, and use of the agent