INVESTIGATION OF FACTORS INFLUENCING THE PROCESS OF EXTRACTING ANTIOXIDANT SUBSTANCES FROM WALNUT SHELLS
Sultanova M. Abdrakhmanov K. Akzhanov N. Saduakas A. Nurysh A.
2022Consulting and Training Center - KEY
Journal of Hygienic Engineering and Design
2022#40184 - 190 pp.
Walnuts are one of the most waste-intensive products of nature. The 67% of walnuts are composed of shell and husks-low-value by-products rich in phenolic compounds. Phenolic compounds extracted from walnut shells are potentially good natural sources of antioxidants for the food and pharmaceutical industries. According to the patent search and analysis of the results of numerous studies, walnut shells, along with phenolic acids, are rich in polyphenols, which are a natural antibiotic with a great therapeutic effect. Walnuts have a greater antioxidant capacity than any other nut, since the shell is mainly composed of lignin, a strong source of phenols. Natural antioxidants, such as phenolic compounds, are becoming increasingly popular due to their positive effects on human health. Studies have shown that lignin, whose chemical composition is a source of antioxidants, characterizes the rigidity level of the shell. The object of the study is a walnut shell growing in the southern regions of the Republic of Kazakhstan. The purpose of this research is to study the biologically active substances extracted from the walnut shell. The material for the study is a walnut shell of two varieties (“Kazakhstan” variety and the “Ak-Terek peaked” variety, these samples are common varieties of walnut grown in the Republic of Kazakhstan). The crushing of the shell was carried out in two stages. Preliminary crushing with the “Novital Magnum 4V” crusher to fractions of 1-2.5 mm and final-to fractions of 300 µm on the laboratory ball mill “MSHL-1P”. The duration of grinding varies from 20 minutes to 3 hours, depending on the size of the crushed material. Extraction was carried out on a semi-automatic apparatus according to the ASV-6 Soxlet, where 30 g of the test sample was extracted with 300 mL of alcohol and an aqueous alcohol solution, the concentration of the solvent (the ratio of ethanol to water) varied from 60 to 90%. The total phenol content was evaluated by the Folin-Ciocalteu colorimetric method, and the results were expressed in milligrams of gallic acid equivalents (mg GAE/extract). To obtain a mathematical model of the technological process, which is a regression equation, a rotatable second-order plan (Box plan) was used. As a result of the conducted research, it was found that ethanol and water as extraction solvents lead to a higher extraction yield, and they are safer and less toxic than methanol and other organic solvents. With an ethanol concentration of 90%, a grinding fineness of 300 microns and an extraction duration of 120 minutes, the maximum extract yield reaches 5.01%. As a result of extraction from walnut shells (90% ethanol, grinding fineness of 300 µm and extraction time of 150 minutes), the phenol content index prevailed. Based on the analysis of data, it was revealed that solvents, grinding and duration are the basis for the regularity of the release of antioxidant substances from walnut shells. Knowledge of the patterns of extraction of antioxidant substances from walnut shells will allow you to adjust the extraction process and obtain products with the specified characteristics and parameters. Thus, the highest yield of the extract depends on the concentration of the solvent and the fineness of the grinding. According to the qualitative ratio, the extracts obtained showed the presence of a high level of phenolic compounds, flavonoids and tannin, which suggests that walnut shell has antioxidant properties and varying degrees of antiviral activity, can have numerous health-improving effects, and is also a natural antibiotic.
Catechins , Extract , Quercetin , Raw materials , Research , Vitamin , Walnut shell
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Astana branch of the LLP “Kazakh Research Institute of Processing and Food Industry”, Akzhol 26, Nur-Sultan, 010000, Kazakhstan
Astana branch of the LLP “Kazakh Research Institute of Processing and Food Industry”
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