Enzymes flour treatments

In the past, the enzyme activities present in malt flour were used for flour treatment. Advances in microbial production of enzymes in recent years has lead to the availability and use of a whole range of more targeted enzyme preparations. 

Soya Proteins. Early attempts to make albumen substitutes from soya protein also ran into problems. A bean flavour tended to appear in the finished product. A solution to these problems has been found. Whipping agents based on enzyme modified soy proteins are now available. The advantage of enzymatic modification is that by appropriate choice of enzymes the protein can be modified in a very controlled way. Chemical treatment would be far less specific. In making these materials the manufacturer has control of the substrate and the enzyme, allowing the final product to be almost made to order. The substrates used are oil-free soy flakes or flour or soy protein concentrate or isolate. The enzymes to use are chosen from a combination of pepsin, papain, ficin, trypsin or bacterial proteases. The substrate will be treated with one or more enzymes under carefully controlled conditions. The finished product is then spray dried. 

Sekul et al. (29) studied the nitrogen solubility properties of enzyme-hydrolyzed peanut proteins. A deionized water dispersion of peanut flour (1 10, w/v) was treated with papain (0.5% total volume) at 45OC for 15 min. Solubility was tested over a range of pH 1 to 9. In general, papain treatment improved solubility at all levels examined except pH 2 and 8 (Figure 6). 

Verma and McCalla ( ) studied the action of pepsin, papain and a commercial fungal protease on wheat gluten. All enzymes acted effectively on dispersed gluten however, the action of different enzymes produced different types of digestion products. Depending upon desired handling characteristics of bread doughs prepared from treated wheat flour, various types of protease treatments can be selected. 

Beuchat (60) investigated the performance of enzyme-hydrolyzed defatted peanut flour in a cookie formula. Flour slurries were treated with pepsin at pH 2.0, bromelain at pH 4.5, and trypsin at pH 7.6. After readjustment to pH 6.9, materials were freeze-dried, pulverized (60-mesh), and then substituted for wheat flour at 5, 15, and 25%. Adjustment of peanut flour to pH 2.0, as well as treatment with pepsin at this pH, greatly improved the handling characteristics of dough in which these flours were incorporated. Use of peanut flours treated at pH 4.5, with or without bromelain, and at pH 7.6, with or without trypsin, improved handling properties of cookie dough. These doughs did not tend to crumble... 

Enzyme hydrolysis of peanut flour also altered the physical characteristics of baked cookies (60). With the exception of the bromelain hydrolysate, the use of peanut flour in cookies resulted in increased specific volume when compared to the 100% wheat flour control. Untreated peanut flour substitution reduced the diameter and increased the height of cookies however, treatment with proteolytic enzymes reversed the behavior. As evidenced by substantial increases in spread ratios, the diameter of cookies containing treated flours increased proportionately more than did the height. These data promote the feasibility of decreasing or increasing the spread of cookies through the addition of various amounts of untreated or enzyme-treated peanut flour. 

The protocol developed by Holm et al. (1986) was evaluated by analysis of starch content in wheat starch, white wheat flour, whole-grain wheat, and industrially processed wheat products. The major advantage of this protocol over the Basic Protocol is its reduced cost. The chemicals for the reagent preparations and the enzymes are purchased directly from the companies that produce them. The original method did not include RS3 (resistant starch) in its quantitation. A DMSO treatment step has been added (step 4) to solve this problem. 

Wheat starch is low in protein, ash and fiber, and contains no residual sulfites. Sulfur dioxide is detrimental to the viscoelastic character of wheat gluten and is not used in the commercial production of wheat starch.28,323 The protein content of ten samples of unmodified and modified wheat starches ranged from 0.06-0.22%.28 A 0.23% protein (0.0404% nitrogen) level in wheat starch essentially indicates a gluten-free starch, as confirmed by an enzyme immunoassay.324 That purity of wheat starch is important in diets for celiac individuals. Wheat starch-based, gluten-free flour products were not harmful in the treatment of celiac sprue and dermatitis herpetiformis,325 although traces of an immunoreactive gliadin can be found in wheat starch.326... 

Partial proteolysis of soybean proteins with endopeptidases has been used to remove flavor compounds and related fatty materials from soybean curd and defatted soybean flour (21). Certain soybean protein concentrates possess an undesirable beany and oxidized flavor. Treatment of soybean curd and defatted soybean flour with endopeptidases such as aspergillopeptidase A released off-flavor compounds such as 1-hexanal and 1-hexanol which could be removed from the hydrolysate by solvent extraction. The enzymically digested products had less odor, taste, and color than the starting material and were more stable to oxidative deterioration. 

Preparation 76), Soluble starch, made from commercial starch by a mild treatment with acid, is hydrolyzed by the enzymes of barley flour to a mixture of maltose and dextrins (see under Maltotriose). These are separated by,fractional precipitation with alcohol, and the crude maltose is recrystallized from aqueous alcohol. Commercial maltose contains considerable quantities of dextrins which are removed by fractional precipitation of an aqueous solution with alcohol. 

Flours are commonly treated with additives and enrichment premixes to standardize quality and meet regulations. The treatments commonly consist of flour bleaching, maturing or aging, enzyme supplementation, and addition of the enrichment to supplement selected minerals and vitamins. Hard wheat flours are, in some instances, oxidized with azodicarbonamide, ascorbic acid and/or, in some countries, with potassium bromate in order to improve functionality. Soft wheat flours are in some instances chlorinated to produce bleached cake flours. The normal range of chlorination ranges... 

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