The vast majority of bread is traditionally produced from wheat flour. Apart from its major constituent starch, wheat flour also contains many other types of substances of which the gluten, the non-starch polysaccharides as well as the lipids are the most important in terms of their impact on the processability of the raw material and in terms of the quality of the final products. We here provide the basics on the processability and quality determining wheat flour constituents and present common concepts on their fate during the breadmaking process as well as on approaches targeted to influence their functionality.

Wheat flour constituents: how they impact bread quality, and how to impact their functionality

Arabinoxylans and Endoxylanases in Wheat Flour Bread-making

The use of enzymes or microorganisms in food preparations is an age-old process. With the advancement of technology, novel enzymes with wide range of applications and specificity have been developed and new application areas are still being explored. Microorganisms such as bacteria, yeast and fungi and their enzymes are widely used in several food preparations for improving the taste and texture and they offer huge economic benefits to industries. Microbial enzymes are the preferred source to plants or animals due to several advantages such as easy, cost-effective and consistent production. The present review discusses the recent advancement in enzyme technology for food industries. A comprehensive list of enzymes used in food processing, the microbial source of these enzymes and the wide range of their application are discussed.

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Applications of Microbial Enzymes in Food Industry.

http://digital.csic.es/bitstream/10261/31075/1/J%20Food%20Engineering-2007-81-42-53.pdf

Improvement of dough rheology, bread quality and bread shelf-life by enzymes combination

Summary Xylan is the second most abundant polysaccharide and a major component of plant cell wall. Cereal xylans contain large quantities of L-arabinose and are therefore, often referred to as arabinoxylans. Xylanases are hydrolytic enzymes, which randomly cleave the b-1,4 backbone of this complex plant cell wall polysaccharide. Different species of Aspergillus and Trichoderma produce these enzymes. Xylanases are of great value in baking as they have been found to improve the bread volume, crumb structure and reduce stickiness. When xylanases are used at optimum levels, they play a significant role in increasing shelf life of bread and reduce bread staling. There is an increasing trend in baking industry towards the application of xylanases in bread production. This review discusses the application of xylanase in the bakery industry, alone and in combination with other enzymes when it shows synergism in the action with them.

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Xylanases and Their Applications in Baking Industry

Nine commercial enzyme preparations and two laboratory-designed mixes with amylase and/or pentosanase/xylanase activity were used to prepare bread samples, and the effects on bread quality and keeping properties were determined. With the doses added, enzymes significantly shortened fermentation time without affecting the pH or the machinability of the doughs. Bread with an improved volume, a greater intensity of aroma and a softer texture was obtained. Loaves had a less intense and characteristic taste and, in some cases, an uneven grain. All enzymes delayed bread firming, but rates varied with each preparation. Factor analysis classified bread samples according to their composition and source.

Functionality of enzymes that hydrolyse starch and non-starch polysaccharide in breadmaking

https://digital.csic.es/bitstream/10261/128384/1/CP113%202014.pdf

Impact of ancient cereals, pseudocereals and legumes on starch hydrolysis and antiradical activity of technologically viable blended breads.

The textural properties of wheat doughs made with different commercial amylases, xylanases/pentosanases, lipases and glucose-oxidase, singly and in mixed combinations, were investigated. Parameters from the texture profile analysis (TPA) and measurement of stickiness (Chen and Hoseney test) were determined after mixing the dough and after it had rested for 3.5 h. Resting of doughs led to softer and less cohesive doughs, with higher adhesive properties. Enzymes acted quickly and induced significant changes in the textural properties of doughs immediately after mixing. The influence of enzymes continued during resting. Xylanases/pentosanases substantially reduced dough consistency and increased stickiness, while addition of glucose-oxidase and specific lipases overcame these effects. Strong correlations could be established between different TPA parameters and stickiness and bread quality characteristics (i.e. volume, density and texture). Bread quality could be described by a single or multiple linear combination of textural variables.

Physical properties of enzyme-supplemented doughs and relationship with bread quality parameters

The rheological behaviour of doughs made with different commercial amylases, xylanases, lipases, and glucose-oxidase, singly and in mixed combinations was investigated. All doughs showed similar trends when subjected to frequency and strain sweep tests. The elastic and viscous moduli increased with frequency, and showed a nonlinear behaviour for strains between 0.2 and 3 %. Phase angle presented a maximum at 5 hz in the frequency plot. Resting of doughs decreased complex modulus and increased loss tangent. Enzyme supplementation resulted in softening and weakening of doughs immediately after mixing, and further effects during resting. Pentosan degrading enzymes caused the main changes, and pure lipase preparations the least significant, when compared with unsupplemented doughs. Glucose-oxidase reduced the softening effect of polysaccharide hydrolysing enzymes.

Rheological properties of enzyme supplemented doughs

In machining, natural oscillations, and elastic, gravitational or temperature deformations, are still a problem to guarantee the quality of fabricated parts. In this paper we present an optical measurement system designed to track and localize in 3D a reference retro-reflector close to the machine-tool's drill. The complete system and its components are described in detail. Several tests, some static (including impacts and rotations) and others dynamic (by executing linear and circular trajectories), were performed on two different machine tools. It has been integrated, for the first time, a laser tracking system into the position control loop of a machine-tool. Results indicate that oscillations and deformations close to the tool can be estimated with micrometric resolution and a bandwidth from 0 to more than 100 Hz. Therefore this sensor opens the possibility for on-line compensation of oscillations and deformations.

/pdf/a-real-time-tool-positioning-sensor-for-machine-tools-47dqhecc81.pdf

Teresa Jiménez

Papers

Functionality of enzymes that hydrolyse starch and non-starch polysaccharide in breadmaking

Impact of ancient cereals, pseudocereals and legumes on starch hydrolysis and antiradical activity of technologically viable blended breads.

Physical properties of enzyme-supplemented doughs and relationship with bread quality parameters

Rheological properties of enzyme supplemented doughs

A Real-Time Tool Positioning Sensor for Machine-Tools