Revealing the features of the composition of the walnut shell from the point of view of the possibility of its use in the food industry

Abstract

This paper considers ways of using walnut shells for food products. The study is based on three varieties of walnut as raw materials. Such physicochemical indicators as the shape, mass, thickness, kernel yield, fat, protein, ash, vitamins, minerals, amino acids, and bioflavonoids have been investigated. The results showed that the walnut shell has a large, rounded, and round-ovoid shape. The weight of the shell ranges from 11.7 to 14.1 g, the thickness ‒ from 1.5 to 1.6 mm, the kernel yield ‒ from 45.7 to 48.8 %. The fat content ranges from 0.7 to 0.9 %, the protein content ‒ 2.4 to 2.5 %, the ash content ‒ from 1.6 to 1.7 %. The study of vitamins in the walnut shell showed that vitamin A is absent in the shell of all varieties of walnut. The content of the vitamin E ranges from 8.59 mg to 9.53 mg, the content of the vitamin C ‒ from 9.31 mg to 15.0 mg, and the content of β, carotene, ‒ from 0.053 to 0.070 mg. The studies have also shown a fairly rich amino acid composition of walnut shells. The results demonstrated that the shell of walnut contains a sufficient amount of daily intake of vitamins. The results of investigating mineral substances showed that the iodine content ranges from 5.52 μg to 14.81 μg, iron ‒ from 3.33 mg to 7.39 mg, and zinc ‒ from 3.1 mg to 6.9 mg. The content of quercetin in the shell of a walnut ranges from 0.945 mg to 1.51 mg, catechin ‒ from 2.46 mg to 12.07 mg, tannins ‒ from 611.32 mg to 805.62 mg. Based on the results of the analysis, it is planned in the future to devise technology for obtaining an extract that could be used as a food additive in a soft drink, enriching it with the missing nutritional components.

Walnut By-Products and Elderberry Extracts—Sustainable Alternatives for Human and Plant Health

“…In agreement with this study and others [ 43 , 47 , 48 , 49 ], the walnut shell contains the following bioactive compounds from the classes of naphthoquinones (juglone and 1,4-naphthoquinone), tannins (tannic acid), hydroxybenzoic acids, hydroxycinnamic acids (sinapic acid and rosmarinic acid), and flavonoids ((−) epicatechin, myricetin, and apigenin) in larger amounts ( Table 3 ). It may also be noted that the walnut shell contains six times more juglone than walnut leaves.…”