Investigating the carbohydrate content of potato at the time of harvest

Introduction:

 Potato with scientific name Solanum tuberosum. L is a plant that is cultivated as an important crop in all countries and is known as a source of carbohydrates, proteins, and vitamins in the human diet. This is a native product of South America and its origin is from Peru. After wheat, rice and corn, potato is the fourth product in people's food basket, which in Iran sometimes takes the place of rice and takes second place, which shows its importance in meeting people's food needs. According to the reports of the Food and Agriculture Organization of the United Nations, the area under potato cultivation in Iran in 2019 was more than 164 thousand hectares and the harvested product from this area was about 32.5 million tons. In the food industry, this product is transformed into various products such as baked potatoes, fried potatoes, potato chips, potato starch, dry fried potatoes, etc.Agria, Sante, Arinda, Marfona, Jelli, Born, Satina, Milva, Banba, Fontane, Ramos and Esprit varieties are among the most common potato varieties in Iran. Due to the increasing expectations for food products with high quality and safety standards, it is necessary to accurately, quickly and purposefully determine the characteristics of food products. In the apple-potato product, quality assessment after the harvest stage is necessary to provide a reliable and uniform product to the market, because potatoes, like many other products, have uneven quality and handling during the harvest stage. - Be At the same time, the safety and desirability of food play an important role in the food industry and are directly related to people's health. In addition, a huge part of the potatoes used in the processing industry is stored, so considering the importance of this food item and the demand of the people throughout the year, it is possible to meet the needs of the applicants only through long-term storage with optimal conditions was responsible. Potatoes for the processing industry must have some requirements such as low sugar content, high dry matter and specific weight, high antioxidants, light skin color and no sprouting. Storage conditions after harvesting can cause changes in the chemical composition and quality of the product.The nutritional and chemical composition of potatoes differs from each other depending on the variety, storage period, growing season, soil type and pre-harvest nutrition. In general, potatoes contain 70-80% water and 16-24% starch and contain small amounts (less than 4%) of protein, fat, anthocyanins, minerals, etc.Storage conditions after harvesting can cause many changes in the chemical composition of potato tubers and as a result, change the quality characteristics of the final product. Sugar and starch are the main components that are affected by metabolism after harvesting in the potato tuber and may ultimately affect their texture, sensory and cooking properties.The quality of potatoes and, consequently, the quality of processed products, significantly depends on the variety and environmental conditions, both during the growing season and during the storage period.Although the quality of raw potatoes is determined primarily by the size, shape, color and attractiveness of the tuber, its quality is mainly determined by examining the quality of the final product. The quality of processed potato products is evaluated in terms of color, flavor and texture, and most of their quality depends on the quality of raw potatoes.By analyzing the relationship between the color of chips, dry solids, sucrose, reducing sugar, ascorbic acid, protein and storage temperature data, Meza showed that dry solids, reducing sugar and sucrose in determining the color of fresh potato chips and reducing sugar, tuber temperature and sucrose content are very important in determining the color of stored tuber chips, and the relative importance of each of these parameters changes with the variety and age of potato tubers.

different varieties of potato were prepared from Arallo Agricultural Research Center (Ardebil Province) immediately after harvest. Then, data collection was done from different samples and cultivars (measurement of carbohydrate content) as explained below.The carbohydrate content of the samples was extracted using the equipment available in the central laboratory of Mohaghegh Ardabili University. This process was carried out by the Schlegel method, in which carbohydrates were extracted using 95% ethanol based on the sulfuric acid method in each sample. The amount of light absorption of each sample was obtained from a nano-spectrophotometer device (Nanodrop) with a volume of 1000 microliters (Figure 1) using a cuvette (made by Termo scientific company from the USA) and the amount of extracted carbohydrates were obtained based on micrograms per millilitre from the standard curve.Glucose was used to prepare the standard curve. Serial dilution of glucose was prepared and color development at 490 nm was controlled for different concentrations of glucose and one millilitre of distilled water was used as a blank. This standard curve was used to calculate the concentration of total carbohydrates in the samples. The standard curve had a coefficient of determination of 0.9955.For each sample, data collection was done in three repetitions and the amount of absorption wavelength and then the amount of carbohydrate was calculated.

In order to obtain the number of carbohydrates, the number of the absorption wavelength was placed in the relationship obtained from the standard curve, and the number of carbohydrates was obtained in micrograms per millilitre. The results of the analysis of the variance of the effect of cultivar on potato carbohydrate content can be seen in Table 1. According to the analysis of the variance table, the effect of variety on potato carbohydrate content was significant at the 1% probability level.As you can see, Sante and Esprit cultivars have more carbohydrates than other cultivars. Also, the carbohydrate content of the Marfona variety was the lowest.According to the data and results of the research, it was observed that the amount of carbohydrates in different potato cultivars is different, and Sante and Esprit cultivars had more carbohydrates at the time of harvest. Also, according to the resulting graphs, it was observed that the amount of carbohydrates of the Marfona cultivar is lower than other cultivars. It is recommended to choose a more suitable variety according to the type of consumption and the importance of quality characteristics for consumption and processing, according to the storage conditions and time.