Abstract
We studied and analyzed the components of the biological value of broccoli, the variety of Parthenon, cultivated in the regions of Ukraine. The research results are reported, the changes in the content of ascorbic acid, isothiocyanates were analyzed, as well as a pigment composition: chlorophyll and β-carotene in the freshly harvested broccoli, as well as after its pretreatment before freezing: by blanching and aging in a solution of food salt. It was proved that the best technique for the pre-treatment of broccoli before freezing, which allows its original consumer properties to be maximally preserved, is its aging in a 3-% food salt solution for 20 minutes. Compared with blanching, aging in a salt solution contributes to the maximum retention of the biological value of broccoli. It was established that broccoli of the variety Parthenon contains 116.4 mg/100 g of ascorbic acid. After blanching, losses are 19.3 %. We confirmed a significant reduction in the content of isothiocyanates, by 43 %, as compared to the content in the original raw material. The loss of chlorophyll is 26 %, specifically a-chlorophyll ‒ 10%, b-chlorophyll ‒ 16 %. The ratio of the a- and b-chlorophyll forms changes as well. The results indicate that when aged in a food salt solution, the losses of ascorbic acid are 5 %, isothiocyanates ‒ 28.2 %. The content of β-carotene does not change in comparison with the original raw material, while the chlorophyll content increases by 6.3 %. There are no changes to the ratio of the chlorophyll forms. Stabilization of the content of ascorbic acid is due to the lack of high-temperature treatment and a partial inactivation of ascorbinate- and polyphenol oxidase, which is explained by the capability of chlorides to remove copper ions from copper-containing compounds to which these enzymes belong. The insignificant losses of vitamin C are due to the water solubility of ascorbic acid. A pre-treatment in a food salt solution induces an increase in the content of a-chlorophyll and b-chlorophyll, which is predetermined by the compensatory reaction.
Highlights
Providing consumers with a sufficient amount of fruit and vegetable produce, the level of consumption of which, according to WHO recommendations, is 400 g/per person/per day, is directly dependent on the agro-climatic conditions of cultivation [1]
The results showed that the classic broccoli freezing technology, which implies preliminary blanching, significantly reduces the biological value of broccoli
The research results we report here are only part of the comprehensive work aimed at stabilizing the biological value of frozen broccoli
Summary
Providing consumers with a sufficient amount of fruit and vegetable produce, the level of consumption of which, according to WHO recommendations, is 400 g/per person/per day, is directly dependent on the agro-climatic conditions of cultivation [1]. Despite the described positive dynamics in terms of the increased stocks of fruits and vegetables, more than 40 % of people suffer from a so-called “latent hunger” due to the consumption of food products of low biological value. The deterioration of environmental situation, the intensification of agriculture, technological techniques for processing, do not contribute to the preservation of the content of biologically active substances in products. The value of broccoli is predetermined by the content of ascorbic acid, vitamin K, chlorophyll, carotene, mineral elements, glucosinolates. In order to stabilize the consumer properties of frozen fruit and vegetable products, the technology of low-temperature treatment employs various techniques for the pre-treatment of plant raw materials before freezing. It is important to determine the optimal pre-treatment techniques before freezing, in order to ensure the stable quality of the frozen products during low-temperature storage
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