It is commonly accepted that aging, particularly during the first 4 or 5 weeks, improves the quality of flour for making bread. Dunlap has reported that he has always obtained better results with aged than with fresh flour. Some of his results are given in Table 46.

Table 46 The Effects of Initial pH of Flour Upon Baking Results (Dunlap)

pH

Acidity

Total minutes fermen-tation

Volume cc.

Color, per cent

Tex-ture, per cent

Value, per cent

Fresh.............

6.12

0.139

215

2160

100

100

100.0

Matured I........

5.90

0.158

198

2250

103

102

103.0

Matured II.......

5.69

0.178

186

2300

104

103

104.5

Matured III......

5.48

0.198

173

2400

105

104

106.7

Matured IV.......

5.29

0.216

153

2520

106

105

100.2

Sherwood and Bailey report that loaf volume, color, and absorption improve during the first few months of aging, but the loaf volume may diminish after extended storage, even though the color and hydration capacity continue to improve. They found that proteolytic activity gradually decreased in storage, sprouted wheat flours retaining their activity in storage for a few years. The improvement in baking quality with aging has been ascribed to the increasing acidity, the increase in free fatty acids, and the diminution of proteolytic activity.

Acidity. The acidity of flour increases in storage, the pH of aged being lower than that of freshly milled flour. However, Bailey believes that the increased acidity is not the only factor responsible for improvement in baking strength, for, if this were the case, the baking quality could be improved by the addition of acids to doughs from fresh flours.

Free fatty acids. Kozmin attributes the improvement with aging to the development of free fatty acids. The removal of free fatty acids rejuvenated the flour, its bread-baking properties returning to their original state. In turn, the addition of free unsaturated fatty acids produces the same effect as natural aging. Unsaturated fatty acids had more effect than saturated ones. Aging or the development of free fatty acids occurred more rapidly as the storage temperature increased.

Sullivan, Near, and Foley state that their results agree well with those of Kozmin, with the exception that American flours do not show the improvement which European flours do with the presence of free, unsaturated fatty acids. It was found, however, that after oxidation of the unsaturated acids had occurred that the baking quality was seriously damaged.

Proteolytic enzymes. Balls and Hale state that the changes that take place in the quality and behavior of flours after bleaching or storage in air are due to the diminution of proteolytic activity.