Sugars accumulation and quality in the fruits of sweet cherry during ripening

Abstract: 【Objective】Fruit quality is the most important character for the consumers, which mainly includes size, color, firmness, contents of sugar and acid as well as antioxidant substances.Many studies of sweet cherry have focused on changes of qualities, anthocyanidin and sugar content during fruit development.However, very few study on correlation between sugars accumulation and qualities development of sweet cherry fruit during ripening has been made so far.The objective of the study was to clarify the correlation between the sugars accumulation and quality development of sweet cherry during fruit ripening.【Methods】The changes of sugars and qualities (firmness, pulling force of peduncle, titratable acidity, total phenolic and ascorbic acid) of sweet cherry (Prunus avium L.‘Rainer’, ‘Van’) were studied during the course of ripening.Uniform fruits of sweet cherry were taken as experimental sample from the hardcore period.Samplings were made on May 20 (ripening period 1) , May 23 (ripening period 2) , May 26 (ripening period 3) , May 29 (ripening period 4) , May 31 (ripening period 5) and June 8 (ripening period 6) 2016 respectively.The fruit soluble sugars and quality indicators were determined immediately after fruit harvest.The correlation of fruit firmness, soluble solids, titratable acidity, ascorbic acid, total phenolic, glucose, fructose, sorbitol and pulling force of peduncle were analyzed by SPSS 17.0.【Results】With the growth and development, fruit color changed from green to yellow, pink, and red gradually.Glucose, fructose and sorbitol were the major soluble sugar components of sweet cherry, and the glucose, fructose, sorbitol, soluble solids, sugar/SSC statistically increased during fruit ripening.Glucose content was the highest, followed by fructose, and sorbitol.Sucrose was not checked out in sweet cherry.The three soluble sugar contents of‘Rainer’and‘Van’accumulated quickly at ripening period 3 and 5 respectively.The glucose, fructose and sorbitol contents of‘Rainer’and‘Van’at harvest were 2.8, 3.6 and 6.7 times, and 1.9, 5.0 and 5.0 times as much as those at early growth periods respectively.The sugar/SSC of‘Rainer’and‘Van’were 90.3%and97.6%, which were 1.8 times and 1.3 times as much as those at early growth period.The firmness and pulling force of peduncle decreased during fruit ripening, and total phenolic content decreased quickly at ripening period 3, and then decreased.The titratable acidity, ascorbic acid content and SSC/acid ratio showed the general upward trend, and titratable acidity and SSC/acid ratio of‘Rainer’decreased after ripening period 2.However, the titratable acidity of‘Rainer’and the ascorbic acid of‘Van’decreased at the fully ripe stage.There were significant correlations between glucose, fructose, sorbitol, soluble solids, firmness and pulling force of peduncle.【Conclusion】The major soluble sugar components of sweet cherry were glucose, fructose and sorbitol.The sugar content increased during the course of ripening, and the ripening period 3 and 5 were the critical periods for sugars accumulation of‘Rainer’and‘Van’respectively.The firmness, pulling force of peduncle and total phenolic content decresed, during the course of ripening.The changes of other quality indicators of the two cultivars were different during the course of ripening.