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Effect of Proofing Time and Wheat Flour Strength on Bleaching, Sensory Characteristics, and Volume of French Breads with Added Soybean Lipoxygenase
Author(s) -
Junqueira Roberto M.,
Rocha Fabrício,
Moreira Maurílio A.,
Castro Inar A.
Publication year - 2007
Publication title -
cereal chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.558
H-Index - 100
eISSN - 1943-3638
pISSN - 0009-0352
DOI - 10.1094/cchem-84-5-0443
Subject(s) - chemistry , food science , lipoxygenase , wheat flour , volume (thermodynamics) , randomized block design , horticulture , enzyme , biochemistry , physics , quantum mechanics , biology
Soybean lipoxygenase addition in wheat bread doughs is widely used to improve the crumb color and rheology but little is known about the variability of the activity of lipoxygenase under diverse breadmaking conditions. Thus the objective of this study was to evaluate how soybean lipoxygenase can affect bleaching, volume, and sensory characteristics of French breads when proofing time and wheat flour strength varies. A 3‐factor Box‐Behnken design was used in this study containing one block and three independent variables or factors designated by exogenous lipoxygenase activity ( x 1 = 0–71 unit/μg of protein), wheat flour deformation energy ( x 2 = 231–258 × 10 –4 J), and proofing time ( x 3 = 2–6 hr). Breads were randomly prepared and all assays were repeated three times. Specific volume (from 5.8 ± 0.4 to 9.9 ± 0.4 cm 3 /g), sensory quality (from 5.2 ± 0.8 to 8.3 ± 0.6), and yellow hue (from 12.6 ± 0.5 to 16.2 ± 0.3) significantly changed ( P < 0.01) among the treatments. Specific volume of the breads increased with higher values of wheat flour strength and proofing time (ŷ vs = 7.5 + 0.9 x 2 + 1.2 x 3 +0.5 x 2 x 3 ). Sensory quality improved at higher values of wheat flour strength and shorter proofing time (ŷ sq = 7.8 + 0.7 x 2 – 0.2 x 3 – 0.4 x 2 2 – 0.6 x 3 2 + 0.5 x 2 x 3 ), while lower and more desirable values of yellow hue were achieved at longer proofing time, higher activity of lipoxygenase, and using stronger wheat flours (ŷ b = 13.7 – 1.2 x 1 – 0.5 x 2 – 0.2 x 3 + 1.0 x 1 2 – 0.3 x 1 x 2 ). All regression models showed a good fitness to the experimental data (lack‐of‐fit P > 0.05) and the difference between predicted and observed values were also not significant ( P < 0.05). Our results suggested that proofing time and wheat flour strength have a greater effect on volume and sensory quality of French breads than soybean lipoxygenase. However, the bleaching effect of this enzyme showed positive interaction with proofing time and wheat flour strength, suggesting its application even when strong wheat flours are used for the manufacture of French breads.