Variability in chemical composition of eggplants and sweet peppers

Abstract

The purpose was to study the variability of the dry matter and vitamin C contents in eggplants, depending on the subspecies and varieties; to determine the dry matter, vitamin C and total sugar contents in sweet peppers, depending on the color of industrially or biologically mature fruits; to establish the dynamics of these indicators during sweet pepper ripening.

Materials and methods. The eggplants belonging to the West Asian and East Asian subspecies were chemically analyzed. Accessions with industrially mature dark-violet, violet, light-lilac and white fruits were studied. Sweet pepper accessions with differently pigmented fruits in the industrial maturity phase were chemically analyzed. There were sweet pepper accessions with industrially mature violet, dark-green, light-green, white-cream and light-yellow fruits. The stability of the chemical contents was assessed using the Lewis stability coefficient.

Results and discussion. Eggplant. An increase in the dry matter content was noted in fruits that contained more anthocyanins (darker fruits). Visual examination showed that the varieties with high dry matter content have a glossy surface, tough peel, firm flesh and are more suitable for transportation and storage. At the same time, elevated temperatures and drought during the growing period were found to contribute to high concentrations of dry matter. The vitamin C accumulation depended on the subspecies, but not on the fruit color.

In general, the "dry matter content" trait is characterized by low variability. The stability of this parameter in the West Asian subspecies accesssions was slightly higher (Lewis coefficient 1.03).

The stability of the vitamin C content in eggplants was above average, regardless of the subspecies. This indicator was more stable in the East Asian subspecies accessions with light-lilac fruits.

Sweet pepper. There was an upward trend in the dry matter content in the accessions with industrially mature dark fruits. The highest dry matter content was recorded for the accessions with industrially mature dark-green fruits. This accession accumulates dry matter during ripening, has a thin pericarp and can be used for processing into paprika. The accessions with light fruits and a thick pericarp have a lower dry matter content, which slightly increases during ripening.

There was a trend in the vitamin C accumulation in all the accessions during ripening. The vitamin C amount depended on the genotype; no association with color was seen; visual examination showed that the accessions with a thick pericarp contained more vitamin C. As they ripen, the total sugar content in sweet peppers increases, depending on the genotype. There was a trend in the total sugar accumulation in the accessions with industrially mature cream and yellow fruits.

The stability of the chemical parameters of sweet pepper was calculated using the Lewis coefficient. The "total sugar content" trait is quite stable within the genotype. The "vitamin C content" trait is highly variable, both within the genotype and from accession to accession under the same growing conditions.

Conclusions. 1. Eggplant. The dry matter content in eggplants depended not only on the subspecies, but also on the fruit color. In the East Asian subspecies accessions, the dry matter content is slightly higher (by 0.3–0.5%) than that in the West Asian subspecies ones. There was also an increase (by 0.1–0.2%) in the dry matter content in fruits containing more anthocyanins (darker fruits). In general, the "dry matter content" trait is characterized by low variability. The stability of the "dry matter content" trait in the West Asian subspecies accessions was slightly higher (Lewis coefficient 1.03). The effect of subspecies and varietal characteristics on the dry matter content in eggplants ranged 61 to 65%. The effect of the "weather during cultivation" factor was about 20%, and the factor interaction effect – 15–18%. The stability of vitamin C content in eggplants was above average, regardless of the subspecies.

2. Sweet pepper. There was an upward trend in the dry matter content in the accessions with industrially ripened dark fruits (by 0.5–2.2%). The accessions with light fruits and a thick pericarp accumulated slightly less dry matter (6.1–6.8%), and the dry matter content slightly increased during ripening. The "dry matter content" trait in sweet peppers was quite stable within the accession, but variable from accession to accession the same growing conditions. The vitamin C content depended on the degree of fruit maturity. There was a trend in the vitamin C accumulation in all the accessions during ripening. The vitamin C amount depended on the genotype, and visual examination showed that the accessions with a thick pericarp contained more vitamin C. There is a trend in the total sugar accumulation in the accessions with industrially mature cream and yellow fruits. The "total sugar content" trait was quite stable within the genotype. The "vitamin C content" trait in sweet peppers was more stable in the accessions with light-yellow fruits (Lewis coefficient 1.03%). The vitamin C content was highly variable (114–200.6%) and depended primarily on the genotype. It was found that the genotype effect on the vitamin C content in sweet peppers ranged 72 to 75%. The effect of the "weather during cultivation" factor was about 26%, and the factor interaction effect – 20–22%