Effects of defatted walnut meal as a potential ingredient in bread: physicochemical, rheological, functional and sensory properties

Abstract

Potential functional ingredients, resulting after partial oil extraction by cold pressing, present a promising direction with perspective for the nutritional improvement of traditional bakery products and may enhance their health-promoting properties. The current study sought to determine the effect of wheat flour substitution with walnut (Juglans regia L.) meal by 0, 2, 4, and 6% of the total amount. The influence of partially defatted walnut meal (BWF) incorporation on dough physicochemical, and rheological properties, as well as the final sensory properties of the bread was investigated. Mixolab test results indicated an increase in dough development time and stability, a reduction of hydration capacity, free water content, enzymatic activity as well as a reduction of the shelf life of the enriched bread. Physical and sensory analyses showed that substitution of wheat flour with partially defatted walnut meal below 6% (on a flour basis) in bread manufacturing recipes yielded products with an enhanced porosity (72.2 to 74.5%), titratable acidity (1.4 to 2.3 degrees), freshness (2.0 to 7.8%) and polyphenol content (0.09 to 2.20 μg GAE/100 g product). All samples show specific positive characteristics, well defined, without defects, with a total acceptability of 4.54 - 4.88. The samples with 2% and 4% BWF show better quality indicators, therefore they can be recommended to consumers as products with high nutritional value.