ISHS Acta Horticulturae 682: V International Postharvest Symposium
MODIFICATIONS IN BIOSYNTHESIS OF AROMA VOLATILE COMPOUNDS IN ´FUJI´ APPLES AFTER CONTROLLED-ATMOSPHERE STORAGE |
| Authors: | I. Lara, J. Jové, J. Graell, M.L. López, G. Echevarría |
| Keywords: | alcohol dehydrogenase, alcohol o-acyltransferase, pyruvate decarboxylase, Malus x domestica, multivariate analysis |
| Abstract:
Albeit widely used to extend commercial availability of apples, controlled atmosphere (CA) storage may decrease volatile production in some apple (Malus × domestica) cultivars, and hence be detrimental to fruit aroma. ‘Fuji’ apples were stored under air (21 kPa O2: 0.03 kPa CO2) or under three different CA conditions (3 kPa O2: 2 kPa CO2; 1 kPa O2: 1 kPa CO2; or 1 kPa O2: 2 kPa CO2) for 3, 5 or 7 months. Emission of volatile compounds and some related enzyme activities were assessed 4 days after removal from storage. Data were used for multivariate analysis of results. Storage caused modifications in aroma profile of ‘Fuji’ apples during subsequent shelf life. Principal Component Analysis (PCA) showed that both storage atmosphere and storage period accounted for differentiation among samples. Most of the selected volatile compounds were associated with AIR-stored fruit, and their emission was higher after medium-term (5 months) storage. Partial Least-Square Regression (PLSR) models revealed that pyruvate decarboxylase (PDC) activity explained part of the discrimination between storage periods, whereas acetaldehyde content was partly responsible for differences between storage atmospheres. Therefore, both variables largely influenced volatile emission after storage. Alcohol dehydrogenase (ADH) activity also accounted for differentiation between storage atmospheres. Acetaldehyde is a substrate for ADH-catalysed reduction to ethanol, which can be subsequently acted upon by alcohol o-acyltransferase (AAT) to synthesise the corresponding ethyl esters. Therefore acetaldehyde is suggested to be an important precursor to ester biosynthesis after storage. AAT activity accounted for differences between storage periods, and was highest after medium-term storage, which corresponds with the highest emission of volatile compounds. | |
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