Technological properties of semi prepared dough with walnut leaves powder

Abstract

Background. Improving the quality of short crust pastry cookies is mainly achieved by using artificial food additives, so that their usefulness is reduced. Thereby unconventional natural ingredients, not investigated and not fully represented in the market, are searched. Walnut leaves of Juglans regia belong to such promising plant materials. In previous studies the technology of walnut leaves powder (WLP) was developed and its rational concentration was defined – 1.5 % of flour weight [4; 5]. Developed supplements must also meet technological requirements.
The aim of the research is to identify technological indexes and microstructure of model pastry semi prepared products using WLP.
Material and methods. Within the study such food materials as wheat white flour [6], potable water [7] and WLP [4] were used. Technological indexes (water absorption, consistency, development time, stability and softening) and quality grades were scored on Brabender farinograph at ambient temperature of 21 оC and 44% humidity.
Results. Analyzed semi prepared dough was assigned with codes (B-1, B-1.5 and B-2, respectively) according to content of powder by flour weight. It is defined that addition of WLP to semi prepared dough reduces development time: for the control samples it is 6.2 min, which is by 19.2, 24.0 and 9.6 % higher compared with B-1, B-1.5 and B-2 samples.
It has been identified by that dough consistency index of B-1 and B-1.5 samples is higher by 1.4 and 2.0%, respectively, and B-2 sample – lower by 0.4 % in comparison with the reference. While dough stability index of B-1 sample is lower by 2.9 %, B-1.5 sample – higher by 1.4 %, B-2 sample coincided with the reference. It is established that dough softening index of B-1, B-1.5 and B-2 samples is 26.2, 31.1 and 42.6 % respectively and is higher compared with the reference. This fact may be explained by impact of organic acids available in WLP on partial peptization of gliadin and glutenin during dough proofing.
Analysis of microstructure pictures of analyzed semi prepared dough showed that B-1 sample, except for color, differed from the reference only with slight WLP inclusions. The picture of B-1.5 sample has areas with several hues identified, that may indicate heterogeneity of flour colloid swelling in this sample. Analysis of the picture of B-2 sample showed significant heterogeneity of its structure. However, the area occupied by its unhydrated particles is significantly higher compared with previously studied semi prepared dough.
Conclusion. It has been established that walnut leaves powder in low concentrations doesn’t significantly influence the technological parameters and structure of semi prepared dough. It confirms the practicability of its usage as a source of biologically active substances in pastry technologies, including short crust cookies.