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In this paper, characteristics and chemical composition of chaenomeles fruit juice are reported for different taxa in the genus Chaenomeles (C. japonica, C. speciosa, C. cathayensis, C. japonica x C. speciosa, and C. x superba). Average fruit weight was 27–211 g and the juice yield was 42–50% based on fresh weight of fruits. The chaenomeles juice was very acidic, with a pH of 2.5–2.8, and the titratable acidity was at most 4.2% calculated as anhydrous citric acid. The content of vitamin C and phenols was in general high, 45–109 mg ascorbic acid and 210–592 mg phenol per 100 ml juice, respectively. Three main organic acids were detected in the juice: malic acid, quinic acid and succinic acid. Of the organic acids malic acid was present in the highest amount, at most 5.1 g/100 ml. Ten amino acids were detected: phosphoserine, aspartic acid, threonine, serine, asparagine, glutamic acid, alanine, phenyalanine, γ- aminobutyric acid and lysine. The most abundant amino acid was glutamic acid (up to 14 mg/100 ml), followed by phosphoserine and aspartic acid (6 mg/100 ml). Five cations were detected: sodium, ammonium, potassium, magnesium and calcium. Of the cations, potassium was present in the highest amount (up to 241 mg/100 ml). Two inorganic anions were present in high amounts: fluoride (up to 139 mg/100 ml) and chloride (9 mg/100 ml). Nine carbohydrates were detected: stachyose, raffinose, sucrose, glucose, xylose, rhamnose, fructose, inositol and sorbitol. Of the carbohydrates, fructose (up to 2.3 g/100 ml), glucose (up to 1.1 g/100 ml) and sorbitol (up to 0.5 g/100 ml) were present in the highest amounts. Due to its characteristics and composition, chaenomeles juice is considered a potential source of valuable compounds and an interesting ingredient for the food industry.

In this paper, studies on the changes in characteristics and chemical composition of Japanese quince (Chaenomeles japonica) fruits and fruit juice during fruit ripening and storage are reported. Juice was extracted from unripe, mature and stored fruits, respectively, and pH, density, viscosity, turbidity, content of soluble and insoluble solids, titratable acidity and content of vitamin C and phenols were analysed. Fruit biochemistry was clearly influenced by genotype and site of cultivation of plants. Ripening was associated with an increase in density, soluble solids, titratable acidity and content of vitamin C in the juice. During storage at 1 °C and 5 °C, respectively, the general tendencies for changes in fruit biochemistry were similar for all genotypes analysed. The characteristics of the fresh fruit were well preserved at 1 °C, even during two months of storage. However, after three months a significant loss in juice yield was observed. This was accompanied by browning of the fruit skin, an increase in turbidity of the juice, changes in the content of vitamin C and a modification of aroma. The fruits kept at 1 °C and 85% relative humidity could be stored for a maximum of nine weeks without significant loss in quality. At 5 °C and 80% relative humidity, the corresponding storage period decreased to four weeks.

In this paper, volatile compounds associated with the fragrance and flavour of chaenomeles juice are reported for fruits of different taxa in the genus Chaenomeles (C. japonica, C. speciosa, C. japonica x C. speciosa and C. x superba). Thirty-three genotypes were investigated and sixty volatile compounds were identified. These compounds included thirteen terpenic hydrocarbons, fourteen alcohols, five ketones, fourteen aldehydes and fourteen esters. Samples of C. japonica had the richest aroma profile. Its major components were methanol, ethanol, 1-penten-3-ol, α-terpineol, acetone, ethyl-vinyl-ketone, varelaldehyde, (E)-2-hexenal, ethyl acetate, linalyl acetate, geranyl acetate and ethyl antranylate. Components that were identified in all the species and that could contribute to the fruity, sweet, floral and acid notes of chaenomeles fragrance and flavour were methanol, terpinen-4-ol, α-terpineol, dodecanol, carvone, nonanal, neral, perialdehyde, undecanal, octyl acetate, citronellyl acetate, neryl acetate, geranyl acetate, ethyl antranyllate, α-pinene, ß-myrcene, γ-terpinene, ß-caryophyllene and α-humulene. Principal differences among species could be attributed to some aldehydes, ketones and esters with high volatility found in C. japonica, but not in C. speciosa, C. japonica x speciosa and C. x superba.

Characteristics and chemical composition of chaenomeles seeds and seed oil were investigated in samples of Japanese quince (Chaenomeles japonica) and a hybrid taxon (C. japonica x C. speciosa). The content of oil in the seeds was 6.1–16.8% based on dry weight, with an average value of 8.2%. The content of moisture in the seeds was 40–46%. The average iodine index of the seed oil was 98, and the acidity index was 2.4. Nine fatty acids were detected: erucic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, oleic acid, cis-11-eicosenoic acid, linoleic acid and linolenic acid. The oil was rich in unsaturated fatty acids (89%), linoleic acid and oleic acid being the main types present. The amount of individual fatty acids varied from traces to 53% for linoleic acid. The ratio saturated/unsaturated fatty acid was very low (0.1). Chaenomeles seed oil could thus be useful in e.g. the food industry, if it were competitive from an economic viewpoint.