The Standardization of black-skinned potato tubers growing on the Territory of the Orenburg Region

Mushinskiy A. A.¹*, Dorokhina O. A.², Kochukova A. A.², Bondarenko A. I.²

¹Federal Scientific Centre of Biological Systems and Agrotechnologies of Russian Academy of Sciences, 29,

9 Yanvarya Street, Orenburg, Russia

²Orenburg State Medical University, Department of Economics of Pharmacy, Pharmaceutical Technology and Pharmacognosy, 5, Sharlyk highway, Orenburg, Russia

*Corresponding Author E-mail: ya82@bk.ru

ABSTRACT:

During the research, a morphological description of the potato was conducted. As a result of this research microscopic and spectrophotometric studies were also conducted. In the course of microscopic examination of potato tubers, the classical structure of these raw materials was exactly confirmed. The method of direct spectrophotometry at analytical wavelength 282 nm was used. This method is actual as an element of standardization of tubers of potatoes. The extraction conditions of catechins from tubers of potato are following: extractant is 40 % ethyl alcohol; extraction time is 60 min. The probability of tannins in terms of catechin in potato tubers in the used method is no more than ± 4.01 % (confidence level 0.95). As a result of the application of the above methods, it was possible to determine the quantitative content of the relevant active ingredients in the studied raw materials accurately. The content of total tannins, catechins in tubers of potatoes varies from 16.5 % to 18.3 %. The obtained results allow substantiating the possibilities of practical application of the studied raw materials. The research is relevant and allows to characterize the studied raw materials which are well-known in the food industry in the aspect of medicinal use.

KEYWORDS: Potatoes, Catechins, Tubers, Spectrophotometry, Standardization.

INTRODUCTION:

Potatoes are widely distributed as food, technical and feed crops. In addition to the fact that potatoes are an important food in the human diet, one should also pay attention to them as a medicinal plant. Potato tubers contain from 14.1 to 29.6% of starch. Also, tubers include sugar, fructose, sucrose, fiber, pectin substances, etc. In addition, potato tubers contain vitamins E, H, and microelements: iron, zinc, iodine, copper, manganese, and others. Currently, scientists are attracted to potato tubers with purple or red flesh. According to some literary data² in the tubers of potatoes with red and or purple flesh there are anthocyanins among which catechin and epicatechin are predominant. They provide the red and purple colour of the pulp or skin. In tubers, not only the skin can be pigmented, but the pulp can be coloured in whole or in part².

RESULTS AND DISCUSSION:

Materials: potato hybrid tubers 10.76.32., cultivated in the Orenburg region.

The microscopic study was carried out according to the General pharmacopoeial monograph.1.5.3.0003.15 “Technique of microscopic and microchemical research of medicinal plant raw materials and medicinal plant preparations” using a light microscope of the following brand: Motic DM111 digital microscope¹. From the whole raw materials we prepare transverse and longitudinal sections. Small pieces of underground organs are placed in cold water and kept for about 1 day, then placed in a mixture of 95% ethyl alcohol and glycerin (1:1) for 3 days. Soaked objects are aligned with a scalpel so that they have a strictly transverse or longitudinal section. Cuts are made and microscopic preparations are prepared in a solution of chloral hydrate or glycerin with a solution of 33% and the anatomical and diagnostic signs are examined first with a small, then with a high magnification. Since the potato tubers were examined fresh, we skip the soaking stage. To detect the starch, the obtained sections are placed in 2-3 drops of Lugol's solution, covered with a cover glass and starch grains are observed. Starch grains acquire blue or blue-violet colour. The colour disappears when heated. The prepared preparation should be analyzed immediately after its preparation, since the colouring does not last long¹.

Botanically, the potato hybrid 10.76.32 under study is characterized by the following indicators: a plant of medium height, a spherical light seedling, with a very strong anthocyanin colouration of the base and the apex, lack of base pubescence and medium top pubescence. Root bumps are few. Type of foliage: stem. The leaves are dark green, medium size, dull, hairless, anthocyanin colouring of the midrib of the upper side is weak. The inflorescence is medium in size, with a weak anthocyanin colouration. The tubers are elongated oval, the peel is blue - black, the pulp is blue and motley.

Fig 1. Cross cut potato tuber hybrid № 10.76.32 with black peel. Marked: 1-periderm; 2-cambium; 3-starch grains.

Figure 1 shows the microscopic structure of the investigated tubers. Under the partially thin epidermis (skin), there is a periderm (1) consisting of several rows of dead highly elongated cells of the cork cambium (2) and two or three rows of living cambial cells (phellogen) from which the cork layer is formed. The epidermis is replaced early by secondary integumentary tissue- periderm, therefore an adult tuber is usually covered only with a cork, which more reliably protects the tuber from mechanical damage, drying and penetration of microorganisms. Below it, there are live large thin-walled cells of the parenchyma, the vacuoles of which are filled with cell sap with starch grains freely floating in it³.

Thus, the anatomical study of potato tubers confirms the classical structure of the tuber as a modified shoot.

A spectrometric study was performed to qualitatively and quantitatively evaluate the content of the amount of tannins in potato hybrid 10.76.32 with black skin. For this purpose, a UNICO 2800 spectrophotometer was used in cuvettes with a layer thickness of 10 mm. 1 g (exact weight) of plant materials was placed in a conical flask with a ground stopper. 50 ml of 40% ethanol was added to the raw material. The flask was capped and weighed. A reflux condenser was attached to the flask and heated in a boiling water bath for 1 hour after the boiling of the extractant. After that, the contents of the flask were cooled, weighed and, if necessary, brought to the original weight with 40% ethyl alcohol. The resulting extract was filtered through a filter paper, discarding the first 10ml. 1ml of the obtained filtrate was placed in a 50 ml volumetric flask and made up to the mark with 40% ethanol. Optical density was measured on a spectrophotometer at an analytical wavelength of 282 nm in a cell with a layer thickness of 10 ml⁴.

A quantitative analysis of the amount of tannins (catechin) in the peel and tubers of potatoes is presented in Figure 2.

Fig. 2: Potato Tuber Hybrid Number 10.76.32 with Black Peel.

The obtained spectra were analyzed, the optical densities of the solutions were determined at a wavelength of 282 nm. The quantitative content of tannins in potato tubers in terms of catechin was determined by the value of optical density.

The calculation was carried out according to the formula (1):

where,

D is the optical density;

m is the mass of the raw material, g (exact weight);

W is the mass loss on drying;

144 is the specific catechin absorption rate.

Metrological characteristics of the methodology of quantitative measurement of the amount of tannins in the skin of potatoes in terms of catechins by the differential spectrometry method are presented below in Table. 1. Using the developed methods we analyzed a number of sample practical (table 1) and determined that the content of the amount of tannins varies from 16.5 % to 18.3%.

Metrological characteristics of the tannins in terms of catechins are presented in table 1. Calculated using: 16.5 % to 18.3%.

Table 1: Metrological characteristics of the quantitative determination of the content of the tannins in terms of catechins:

f		S	P, %	t (P,f)	DX	E, %
10	17,9	0.3464	95	2,23	0.77	4.01

CONCLUSIONS:

The microscopic examination confirmed the classical structure of the tuber, as a modified shoot.

Under epidermis periderm was found. In the cells of the parenchyma are numerous starch grains.

An analysis of tuber hybrid No. 10.76.32 with black skin harvested in the Orenburg region showed that the average content of tannins in terms of catechin is 17.9%.

Potato experiments were performed within the framework of the RAS program № No. 0761- 2019-0011.

CONFLICT OF INTEREST:

The authors declare no conflict of interest.

REFERENCES:

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3. Marinchenko V.A., Smirnov V.A., Ustinnikov B.A. et al. Technology of alcohol edited by V.A. Smirnova, _M.: Light and food industry, 1981, 416 p.

4. Khisyamova D.M. Comparative pharmacognostic study of some representatives of the genus Lapchatka (Potentilla L.): dissertation dissertation. Candidate of Pharmaceutical Sciences: 04/14/02/ Khisyamova Dinara Midhatovna; [Place of protection: Sam. state honey. un-t] - Samara, 2017.-24 p.

Received on 10.04.2019 Modified on 25.05.2019

Research J. Pharm. and Tech. 2019; 12(11):5424-5426.

DOI: 10.5958/0974-360X.2019.00940.5