TITLE:
Walnut Meal Whitening and the Impact of Whitening Factors on Its Quality
AUTHORS:
Grosu Carolina, Siminiuc Rodica, Dinu Turcanu, Covaliov Eugenia, Gutium Olga
KEYWORDS:
Walnut Meal, Whitening, Color Parameters
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.12 No.1,
January
18,
2021
ABSTRACT: Walnut meal is a nutrient-rich product and has a high nutritional value.
Walnut meal is a product that can be used in food technology, in order to improve
the nutritional quality, expand the range of confectionery products, and
replaces the walnut kernel. Due to the dark color, the use of the walnut meal in
the preparation of pastries would have a negative effect on the appearance of
some final products and the whitening process would allow its use without
negatively influencing the final product. The aim of the research is to whiten Juglans regial L. walnut meal as a
valuable nutritious raw material. Hydrogen peroxide was used to bleach the
walnut meal, and the pH, concentration of the whitening agent and the
concentration of the meal were used as variable parameters of the bleaching
process. The color descriptors (Whitening index, Saturation index, Total color
difference, Browning index) were calculated to establish the optimal whitening
conditions of the walnut meal. The obtained results showed that an alkaline
medium, with the hydrogen peroxide concentration of 10% and 2.5% meal
concentration allows obtaining the best color parameters in terms of Lightness (82.20) and
Whitening Index (71.20). In addition, the study of walnut meal quality in terms
of peroxide value evolution showed that the treatment with hydrogen peroxide
does not affect in any way the value of the peroxide index of the lipids. The
highest peroxide value (4.91 mmol/g oil) was recorded for the sample bleached
in a 10% Hydrogen peroxide solution, with a pH of 10 against the 4.71 mmol/g
oil for the unbleached sample.