The role of enzymes in modern detergency

Enzymes have effectively assisted the development and improvement of modern household and industrial detergents. The major classes of detergent enzymes—proteases, lipases, amylases, and cellulases—each provide specific benefits for application in laundry and automatic dishwashing. Historically, proteases were first to be used extensively in laundry detergents. In addition to raising the level of cleaning, they have also provided environmental benefits by reducing energy consumption through shorter washing times, lower washing temperatures, and reduced water consumption. Today proteases are joined by lipases and amylases in improving detergent efficacy especially for household laundering at lower temperatures and, in industrial cleaning operations, at lower pH levels. Cellulases contribute to overall fabric care by rejuvenating or maintaining the new appearance of washed garments. Enzymes are produced by fermentation technologies that utilize renewable resources.     

Effect of honey types and concentration on starch gelatinization

The complex and variable composition of honey, depending on source, season and processing, means different honey samples could cause variation in the characteristics of the finished product. The objective of this study was to determine how the minor components present in honey affect starch gelatinization. A Rapid Visco Analyser was used to measure changes in viscosity when unmodified maize starch was gelatinized in a honey or model sugar solution. When honey was compared to equivalent blends of sugars, there was an increase in starch viscosity with increasing levels of addition. However, at the same level, honey gave a lower viscosity than the blends of sugars. Honeys from different sources (differing in pH and amylase activity) show a varied effect on starch gelatinization, with starch viscosity increasing with addition level for six of the honeys, but decreasing with increasing addition level for two honey samples. Varying the pH also produced variation in starch gelatinization patterns between honey types. Between pH 3.0 and 4.0, starch viscosity was similar for all four honey types studied, while above this pH there were differences between all honey types. As expected, starch viscosity decreased as the solution pH neared the optimum for honey amylase activity (pH 5.3-5.6), though it did not increase as the pH moved away from the honey amylase activity optimum. Differences between honey samples, and between honey and a model sugar mixture, in their effect on starch gelatinization was attributed to honey amylase activity and the composition and concentration of minor organic compounds present.     

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

 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. Received:7 November 1996/Revised version: 21 January 1997     

Suitability of Starch Granule Porosity for Biosynthesis and Amylolysis Susceptibility

A packed column procedure was used to estimate the pore volume of native starch granules from seven different botanical sources. Polyethylene glycols (PEG) were employed as probes after determination of their hydrodynamic radius by quasi‐elastic light scattering. The gel phase of native starch granules is penetrable by low‐molar‐mass solutes such as maltooligosaccharides (MOS) or small PEG. Molecules with a degree of polymerization greater than 6—7 were excluded. This size threshold corresponds to carbohydrates with a molar mass of 1,000 g/mol or proteins with a hydrodynamic radius of 0.6 nm. Two‐stage curves were observed for all starches studied. Molecular probes had a diameter of less than 0.6—0.8 nm in the first part and larger diameters in the second part of the curves. The mechanism of size‐exclusion‐chromatography was followed in the first part, the phenomenon of hydrodynamic chromatography was applicable in the second. Regardless of the starch studied, MOS displayed similar behavior, characterized by a higher elution volume than expected from their molecular size.     

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

 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. Received: 21 May 1997 / Revised version: 10 July 1997     

Influence of Selected Parameters of Starch Gelatinization and Hydrolysis on Stability of Amylose‐Lipid Complexes

Dissociation of amylose – lipid complexes (AMLs) upon gelatinization and enzymatic hydrolysis of wheat starch has been examined using differential scanning calorimetry (DSC). Digestion of starch by the thermostable α‐amylase THERMAMYL 120L was carried out under conditions applied for enzymatic hydrolysis of wheat starch in industry, i.e. 5 min incubation at 105°C, followed by 60–90 min hydrolysis at 95°C. For comparison reasons, samples of wheat starch slurries were incubated under the same conditions but in the absence of enzyme. The enthalpy and temperature of AMLs dissociation and the shapes of peaks in the DSC endo‐ and exotherms depended on conditions of starch processing prior to DSC measurements. Wheat starch gelatinization coupled with its digestion by α‐amylase resulted in more pronounced AML degradation as compared to gelatinization in the absence of enzyme. Different shapes of peaks in thermograms and different temperatures of AMLs dissociation and reassociation indicate that different AML polymorphs were generated in the examined samples. Their concentrations depended on conditions (temperature, time and the presence or absence of α‐amylase) of wheat starch treatment.     

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

 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. Received:7 November 1996/Revised version: 21 January 1997     

Heat damage of water biscuits from einkorn,durum and bread wheat flours

To limit heat damage and improve the nutritional properties of bakery products, furosine, glucosylisomaltol, hydroxymethylfurfural, furfural, sugars, α-amylase, β-amylase and colour were assessed during the production of water biscuits from three einkorn, three bread and one durum wheat flours. Heat damage indices, colour and a_w development during baking (from 25 to 75 min duration) of water biscuits from one bread wheat were also studied.