# Profiling Taste and Aroma Compound Metabolism during Apricot Fruit Development and Ripening
## 3 Discussion  
In the study, we firstly presented an analysis of sugars, organic acids, and aroma volatiles metabolism during apricot fruit development and ripening. The key taste and aroma components in apricot were identified by integrating chemical composition with consumers' evaluation. The use of five cultivars removes the complex effect of genetic background, highlighting the common trends and revealing the possible accumulation mechanism of the main flavor compounds underlying development and ripening. In general, the composition of sugars in fruits mainly depends on genetics; however, cultivation condition and environmental factors mainly influence the amount of total soluble sugars. Even the peak sugar levels at maturation or ripening and the sugar accumulation patterns and concentration differ between species and are regulated by fruit development. Sucrose in peach fruit increases until maturity [20]. Fructose and sucrose are the major soluble sugars whereas sorbitol was the major sugar alcohol in mature fruit. As apple fruit develops, fructose significantly increases, which results from sucrose that was transported from the leaves and newly synthesized sucrose, while the sorbitol decreases throughout fruit development, the occurrence of a glucose peak at about 6 weeks after boom [21]. In mango, the major sugars were identified as glucose, fructose and sucrose, and their  
Figure 8: Visualization of [PERSON]’s correlations between flavor compound contents and metabolism enzyme activities during apricot fruit development. The square color corresponds to the correlation value as shown in the legend: blue represents a negative correlation, and red represents a positive correlation. The white squares correspond to non-significant correlations (\(p\) value > 0.01). **(a)** Correlation between enzyme activities of sugar metabolism and sugar contents: SSthy, sucrose synthase for synthesis direction, SPS, Sucrose phosphatesynthase, SSca sucrose synthase for degradation direction, NI, neutral invertase, AI, acid invertase, SDH, sorbitol dehydrogenase, FK, fructokinase, SO, sorbitol oxidase, GK, Glucokinase; **(b)** Correlation between enzymes activities of organic acid metabolism and organic acid contents: QH, quinate dehydrogenase, MS, malate synthase, NADP-ME, NADP-malic enzyme, NAD-ME, NAD-malic enzyme, CS, citrate synthase, GAD, glutamate decarboxylase; **(c)** Correlation between enzyme activities of aroma volatile metabolism and aroma volatile contents: LOX, lipoxygenases, HPL, hydroperoxide lyase, ADH, alcohol dehydrogenase, AAT, alcohol acyl-transferases, ACX, Acyl-CoA Oxidase, CCD, carotenoid cleavage dioxygenases, TPS, repene synthase. All data are expressed as means \(\pm\) standard error of triplicate samples. contents increase during ripening; sucrose was found to be in the greatest concentration throughout ripening process [22]. Glucose and fructose significantly accumulate in sweet cherry during ripening. Fructose and glucose are the main sugars in the date plum persimmon fruit [23]. In the present study, we found that all sugars increased rapidly throughout the whole development process, and glucose and sucrose were the major sugars in pulps or peels of all cultivars tested. At the early stage glucose was the most abundant sugar, and as development proceeds, sucrose accumulation is enhanced significantly. At the late stage of fruit development, the content of sucrose exceeds that of glucose. The apricot cultivars tested mainly accumulated glucose during early development, whereas the fruit mainly accumulated sucrose during ripening, which suggested that the accumulation pattern of sugars in apricot fruit convert from glucose-predominated to sucrose-predominated during fruit development and ripening. In relation to the enzymes involved in sugar metabolism, the drastic increase in SSthy and SPS are responsible for the rapid increase of sucrose, which is consistent with the correlation analysis between enzyme activities and sugar accumulation.