Nutrition value of wild-growing fruits from mountain Dagestan and its safety after fast freezing and cold storage

• B.M. Guseynova

Abstract

Results of research of mineral composition, content of vitamin C and P, titrable acids, pectinaceous and phenol substances in fresh, fast-frozen (t=-30 °C), and also stored within 3 and 9 months (t=-18 °C) fruits of wild-growing blackberry, cornel, medlar and sea-buckthorn are presented in article. Determination of mineral composition was carried out by flame atomic absorption photometry, vitamin C and pectinaceous substances -by titirimetric methods, phenolic substances and vitamin P - by colorimetric methods. Vitamin C content was minimal in fresh fruits of cornel (6.9±0.3 mg%), amounted to 21.7-32.0 mg% in the fruits of blackberries and medlar and reached 180.1±7.2 mg% in the fruit of sea-buckthorn. Vitamin P concentration ranged from 34.9 (sea-buckthorn) to 180.0 mg% (cornel). Berries of a cornel contained also the greatest number of titrable acids (33.2±1.3 g/dm³), phenolic compounds (243.0±4.8 mg%) and pectinaceous substances (2.91±0.08%). The most significant content of potassium (521±15.6 mg%), calcium (133.2±5.2 mg%), magnesium (62.4±2.5 mg%) and iron (2.81±0.05 mg%) was revealed in medlar fruits. Consumption of 100 g of the studied fruits provides daily requirements of a human body, depending on a species of wild plants: in calcium -for 2-13.3%, potassium - for 7.0-20.8%, magnesium - for 8.1-15.6%, iron - for 5.9-19.2% and in vitamin C - from 5.8-24.6 to 145.7% in the case of sea buckthorn. The applied processing method of conservation - fast freezing (t=-30 °С) of fruits and their long storage (t=-18 °С) is the effective way ensuring high safety of nutrients in them. In the studied berries after 9-months cold storage the safety of vitamin C varied ranging from 55.7 (blackberry) to 76.1% (cornel), and vitamin P - from 81.9 (sea-buckthorn) to 92.8% (cornel). Stability of titrable acids, except for medlar fruits, varied from 84.2% (blackberry) to 94.0% (sea-buckthorn). The safety of phenolic and pectinaceous compounds by the end of 9 months of storage, has averaged 90.6 and 95.6% respectively in comparison with their initial quantity in fresh fruits. The mineral composition was the stablest. After completion of experiment the safety of mineral substances in fruits of wild plants fluctuated from 94.6 to 98.5%. Distinctions in change of biochemical complexes of berries of blackberry, cornel, medlar and sea-buckthorn at fast freezing (t=-30 °С) and storage (t=-18 °С), apparently, are caused by specific features, content of free and bound water, thickness of cellular walls, durability of a thin skin of fruits, as well as by concentration of the components that inhibit the destructive processes occurring at the cellular and molecular level.

Keywords:wild-growing fruits, biochemical omposition, vitamin C, vitamin P, pectin-aceous substances, mineral substances, fast freezing

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