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Improving effect of a natural α-amylase inhibitor on the baking quality of wheat flour containing malted barley flour
Journal of Cereal Science 8 (1988) 207-209
Improving Effect of a Natural ex-Amylase Inhibitor on the Baking Quality of Wheat Flour Containing Malted Barley Flour* U. ZAWISTOWSKAt, J. LANGSTAFFt and W. BUSHUKt
tABI Biotechnology Inc., Winnipeg, MB R3T OP4 and tFood Science Department, University of Manitoba, Winnipeg, MB R3T 2N2 Received 13 June 1988
In a normal wheat-growing year in Canada, a significant amount of wheat produced is degraded on account of pre-harvest sprouting. In extremely abnormal years, the extent of sprouting damage may be as high as 15 % of a total production of about 25 million tons (L. Seguin, Canadian Grain Commission, private communication). Similar levels of sprouting damage have recently been experienced in Australia. In Europe, sprouting damage of cereals at relatively high levels occurs almost every year. Flour from excessively sprout-damaged wheat cannot be processed into bread. The major detrimental factor of sprouting damage on breadmaking quality of wheat flour appears to be the excessively high a-amylase activity. Other factors, such as increased protease activity and starch and protein degradation, probably contribute to the overall effect of sprouting damage to an extent that depends on degree of sprouting. The possibility of neutralizing the detrimental effect of excessive a-amylase activity by the addition of inhibitors or by adjusting the baking process (e.g. lowering dough pH, decreasing water absorption, shortening the overall dough stage, increasing baking temperature, etc.) has been investigated 1 • For a variety of reasons, remedial procedures based on the results of those researches have not met with commercial success. In this article we report the first demonstration of the neutralization of excess a-amylase activity in a baking process by the addition of a natural proteinaceous a-amylase inhibitor. These findings should lead to effective utilization of flours from sprout-damaged wheats that are normally too high in a-amylase activity for traditional processing into bread. The base flour used in this study was a commercial' all-purpose' flour milled from Canadian Hard Red Spring wheat. Its protein and ash contents were 12·0 and 0·40 % on a 14% moisture basis, respectively. In the standard Amylograph test 2 , it had a peak viscosity of 310 Brabender Units (B. U.). Its a-amylase activity3 was 8·1 units. The high a-amylase activity flour was prepared by adding an appropriate amount of malted barley flour (Diamalt II, Fleischmann) to lower the peak Amylograph viscosity • Publication No. 122 of the Food Science Dept. University of Manitoba. 0733-5210/88/050207 +03 $03.00/00
~
1988 Academic Press Limited
208
u.
ZAWISTOWSKA ET AL.
TABLE I. Basic bread formula Flour Sugar Milk powder Salt
300 g 17 g 6g
5g
Butter Water Dry yeast (Fermipan)
II g 200 ml 4·5 g
::)
a:i
20
30
Time (min)
Figure I. Viscosity: (a) control. (b) after addition of amylase and (c) after addition of amylase and inhibitor.
Figure 2. Baking results: (a) control, (b) after addition of amylase and (c) after addition of amylase and inhibitor.
NATURAL 'X-AMYLASE INHIBITOR IN BAKING
209
to 180 B.U. by increasing the ct-amylase activity to 23·0 units. a-Amylase inhibitor was prepared from barley, cv. Bonanza, by the procedure of Zawistowska et a/. I Baking was done on a fully automated' Bread Bakery' (Panasonic, model SO-BT2?). The procedure used by this' bakery' is analogous to the Canadian 'remix' baking test 5 • All the ingredients (Table I), including the inhibitor where applicable, were added simultaneously to the mixing-fermentation-baking pan. Addition of inhibitor at the same level as that used in the baking experiments recovered most of the loss in peak Amylograph viscosity (pig. I). There was some residual effect of the added a-amylase and the inhibitor on the Amylograph curve that requires further investigation. Baking results (Fig. 2) showed that addition of excess (more than required for normal baking) of ct-amylase produced the anticipated effect on bread quality-eaving-in of the top and the side-walls and a more open crumb gran. The texture of the crumb was noticeably sticky instead of silky-smooth as in the can trol loaf. The sticky nature of the crumb and the tendency to ball-up in the mouth was particularly noticeable during eating. Addition of the a-amylase inhibitor as one of the bread ingredients completely neutralized the detrimental effect of excess a-amylase. The size and the appearance of the loaf were essentially the same as those of the control loaf. The original grain and texture were fully recovered. These results indicate that the natural a-amylase inhibitor should make it possible to produce acceptable bread from flour with an ct-amylase activity that is too high to produce satisfactory bread without the inhibitor. The authors acknowledge the encouragement and permission to publish of Dr A. D. Friesen (AS! Biotechnology, Inc.). We gratefully acknowledge the technical assistance of E. Slominski and R. R. Zillman (University or Manitoba). a-Amylase activity was determined by J. E. Kruger (Grain Research Laboratory). This work was supported partly by a grant of the Natural Sciences and Engineering Research Council of Canada. References 1. Men:dith. P. and Pomeranz. Y. Adv. Cereal Chell!. Tech. 7 (1985) 239-:UO. 2. Approved Methods of the American Association of Cereal Chemists, AACC, St Paul, MN (1987) Method 22· 10. 3. Kruger, J. E. and Tipples. K. H. Cereal Chelll. 58 (1981) 271-274. 4. Zawistowska, U., LangstafT, J., McVicar, L. and Friesen, A. D. Canadian Patent No. [206157 ([987). 5. Irvine, G. N. and McMullan, M. E. The' remix' baking test. Cereal Chem. 37 (1960) 603 613.
Improving Effect of a Natural ex-Amylase Inhibitor on the Baking Quality of Wheat Flour Containing Malted Barley Flour* U. ZAWISTOWSKAt, J. LANGSTAFFt and W. BUSHUKt
tABI Biotechnology Inc., Winnipeg, MB R3T OP4 and tFood Science Department, University of Manitoba, Winnipeg, MB R3T 2N2 Received 13 June 1988
In a normal wheat-growing year in Canada, a significant amount of wheat produced is degraded on account of pre-harvest sprouting. In extremely abnormal years, the extent of sprouting damage may be as high as 15 % of a total production of about 25 million tons (L. Seguin, Canadian Grain Commission, private communication). Similar levels of sprouting damage have recently been experienced in Australia. In Europe, sprouting damage of cereals at relatively high levels occurs almost every year. Flour from excessively sprout-damaged wheat cannot be processed into bread. The major detrimental factor of sprouting damage on breadmaking quality of wheat flour appears to be the excessively high a-amylase activity. Other factors, such as increased protease activity and starch and protein degradation, probably contribute to the overall effect of sprouting damage to an extent that depends on degree of sprouting. The possibility of neutralizing the detrimental effect of excessive a-amylase activity by the addition of inhibitors or by adjusting the baking process (e.g. lowering dough pH, decreasing water absorption, shortening the overall dough stage, increasing baking temperature, etc.) has been investigated 1 • For a variety of reasons, remedial procedures based on the results of those researches have not met with commercial success. In this article we report the first demonstration of the neutralization of excess a-amylase activity in a baking process by the addition of a natural proteinaceous a-amylase inhibitor. These findings should lead to effective utilization of flours from sprout-damaged wheats that are normally too high in a-amylase activity for traditional processing into bread. The base flour used in this study was a commercial' all-purpose' flour milled from Canadian Hard Red Spring wheat. Its protein and ash contents were 12·0 and 0·40 % on a 14% moisture basis, respectively. In the standard Amylograph test 2 , it had a peak viscosity of 310 Brabender Units (B. U.). Its a-amylase activity3 was 8·1 units. The high a-amylase activity flour was prepared by adding an appropriate amount of malted barley flour (Diamalt II, Fleischmann) to lower the peak Amylograph viscosity • Publication No. 122 of the Food Science Dept. University of Manitoba. 0733-5210/88/050207 +03 $03.00/00
~
1988 Academic Press Limited
208
u.
ZAWISTOWSKA ET AL.
TABLE I. Basic bread formula Flour Sugar Milk powder Salt
300 g 17 g 6g
5g
Butter Water Dry yeast (Fermipan)
II g 200 ml 4·5 g
::)
a:i
20
30
Time (min)
Figure I. Viscosity: (a) control. (b) after addition of amylase and (c) after addition of amylase and inhibitor.
Figure 2. Baking results: (a) control, (b) after addition of amylase and (c) after addition of amylase and inhibitor.
NATURAL 'X-AMYLASE INHIBITOR IN BAKING
209
to 180 B.U. by increasing the ct-amylase activity to 23·0 units. a-Amylase inhibitor was prepared from barley, cv. Bonanza, by the procedure of Zawistowska et a/. I Baking was done on a fully automated' Bread Bakery' (Panasonic, model SO-BT2?). The procedure used by this' bakery' is analogous to the Canadian 'remix' baking test 5 • All the ingredients (Table I), including the inhibitor where applicable, were added simultaneously to the mixing-fermentation-baking pan. Addition of inhibitor at the same level as that used in the baking experiments recovered most of the loss in peak Amylograph viscosity (pig. I). There was some residual effect of the added a-amylase and the inhibitor on the Amylograph curve that requires further investigation. Baking results (Fig. 2) showed that addition of excess (more than required for normal baking) of ct-amylase produced the anticipated effect on bread quality-eaving-in of the top and the side-walls and a more open crumb gran. The texture of the crumb was noticeably sticky instead of silky-smooth as in the can trol loaf. The sticky nature of the crumb and the tendency to ball-up in the mouth was particularly noticeable during eating. Addition of the a-amylase inhibitor as one of the bread ingredients completely neutralized the detrimental effect of excess a-amylase. The size and the appearance of the loaf were essentially the same as those of the control loaf. The original grain and texture were fully recovered. These results indicate that the natural a-amylase inhibitor should make it possible to produce acceptable bread from flour with an ct-amylase activity that is too high to produce satisfactory bread without the inhibitor. The authors acknowledge the encouragement and permission to publish of Dr A. D. Friesen (AS! Biotechnology, Inc.). We gratefully acknowledge the technical assistance of E. Slominski and R. R. Zillman (University or Manitoba). a-Amylase activity was determined by J. E. Kruger (Grain Research Laboratory). This work was supported partly by a grant of the Natural Sciences and Engineering Research Council of Canada. References 1. Men:dith. P. and Pomeranz. Y. Adv. Cereal Chell!. Tech. 7 (1985) 239-:UO. 2. Approved Methods of the American Association of Cereal Chemists, AACC, St Paul, MN (1987) Method 22· 10. 3. Kruger, J. E. and Tipples. K. H. Cereal Chelll. 58 (1981) 271-274. 4. Zawistowska, U., LangstafT, J., McVicar, L. and Friesen, A. D. Canadian Patent No. [206157 ([987). 5. Irvine, G. N. and McMullan, M. E. The' remix' baking test. Cereal Chem. 37 (1960) 603 613.