Ph.D. Kryuk Т. V., Ph.D. Pikula L. F.

Donetsk National University of Economics and Trade

named Mikhail Tugan-Baranovsky, Ukraine

CHANGING OF THE BIOCHEMICAL composition APPLES DURING STORAGE

Today healthy living is in a fashion not only in the West, but also in Ukraine. Each of us knows about the dangers of fatty foods and the benefits of fruits and vegetables, which lies in their ability to prevent diseases and maintain good health for a long time. They are a valuable source of fiber, minerals and vitamins, especially antioxidants - β-carotene, vitamin C and phenolic compounds that protect cells against aging and diseases.

The most popular fruits are apples of different species and varieties in the ration of the inhabitants of Ukraine. This is the perfect healthy meal: low-calories (medium-sized apple contains 100 calories), protects the organism from the cardiovascular diseases, reduces the risk of the formation of the cancerous tumors, normalizes cholesterol in blood, protects tooth enamel from the influence of destructive bacteria, prevents the destruction of brain cells, reduces the level of respiratory diseases, etc. [1]. In addition apples possess a pleasant taste, and their price is available at the Ukrainian food market even for disadvantaged people. All this causes the high consumption of fruits during the entire calendar year.

The period of ripening apples is the fall, late varieties are beginning to gather in early October, but only after 2-3 months of storage they reach the consumer ripeness. These apples are well preserved during the entire winter period and therefore are particularly popular among the population. These include: Reinette Simirenko, Jonathan Wells, Golden Delicious, and others.

The aim of our study was to investigate the changes of the biochemical composition of apples (for example of sort «Reinette Simirenko») during storage.

Storage conditions were as follows: the sorted out, dry apples are picked in a cardboard box, each apple was wrapped in paper. Room temperature ranged from 10 to 12 ^oC with humidity of 45 %. From November to March with a periodicity of 35-40 days we spent the monitoring of the organoleptic and physic-chemical parameters of fruits.

Fruits are packed in the store. They were with the stems and without injuries and pests. Apples had the appearance, shape and taste typical for this class: light-green color with many light circular dots with size 2-5 mm, white, juicy, tender flesh, wine-sweet taste.

The number of basic chemical substances was determined in the initial samples. From the results (Table 1) we can see that the concentration of reducing sugars, pectin, vitamin C, phenolic compounds and total dry substances generally correspond to average statistical content of these components in the apples «Reinette Simirenko» .

Table 1 − Contents of chemical components in fresh apples

Chemical substances	The initial contents	The average content for the sort «Reinette Simirenko» [2]
Dry substances, %	15,0	13,0
Reducing sugars, г/100 г	2,3	10,0
Pectin, мг/100 г	940	1000
Vitamin С, мг/100 г	1,0	7,3
Phenolic substances, мг/100 г	400	354

It is known [3] the losses of the nutrients occurs inevitably during the storage of food caused by ongoing biochemical processes in them, especially such as breathing, self-warming, as well as the processes that are related to the vital activity of microorganisms. Indeed, as shown in Figure 1, during storage of apples there is a significant change in their chemical composition: decreases the concentration of pectin, phenolic compounds and vitamin C. The burning of carbohydrates is the result of the fruits’ breathing, what is reflected in the loss of dry substances as a whole [3]. Indeed, the decrease in the amount of dry substances for 4 months was 15% (Fig. 1).

Figure 1 − Changing of the chemical substances contents during storage of apples

The maximum decrease of concentration is observed for easily oxidized phenolic components and vitamin C compared with other investigated components, them residual concentration is 18 % and 30 % respectively. The level of reducing sugars, however, greatly increases compared with them primary content − more than 25 %. Obviously, this is due to hydrolysis of more complex carbohydrates; such assumption is confirmed by a parallel decrease in the concentration of pectin.

In general, it is clear that biochemical changes occur already at the initial stage of storage, with an increase period of storage the rate of reaction increases. Average loss of nutrients is 10 % already after the first month of storage of apples and after 4 months average losses reach 45 % (Table 2).

In the process of storage organoleptic characteristics of fruit deteriorated significantly. The apples have lost the original luster after 2 months, after 4 – they acquired a yellow color, there was a browning skin, subcutaneous mottling revealed, texture was soft and friable. In general, the appearance of the fruits after 4 months of storage testified that there is a process of microbiological spoilage in them. The consequence of the occurrence of undesirable chemical and biological processes is a marked deterioration in the taste of apples.

Table 2 − Changing of the chemical substances of apples during storage

Chemical substances	Contents by month storage					Losses / increase, %
	0	1 month	2 month	3 month	4 month
Dry substances, %	15,0	14,4	13,6	13,2	12,8	15
Reducing sugars, g/ 100 g	2,3	2,5	2,7	2,8	2,9	27
Pectin, mg/100 g	940	900	865	818	800	15
Vitamin С, мg/100 g	1,0	0,8	0,6	0,4	0,2	82
Phenolic substances, мg/100 g	400	360	280	180	120	70

Thus, it’s necessary to create special conditions for storage to preserve the original nutritional quality of apples, otherwise the nutritional value of fruits is greatly reduced, and eating these fruits during the «vitamin starvation» in the spring has the value of taste only.

References:

1. Яблоки против болезней // [Электронный ресурс]. Режим доступа: http://2medic.ru.

2. Семечковые плоды // [Электронный ресурс]. Режим доступа: http://www.znaytovar.ru.

3. Метлицкий, Л.В. Биохимия плодов и овощей / Л.В. Метлицкий.– М.: Экономика, 1970.– 210 с.