VOLATILE COMPOUNDS IN GOLDEN DELICIOUS APPLE FRUIT (Malus domestica) DURING COLD STORAGE

Abstract

Biosynthesis of volatile compounds (VC), as well as activity of related enzymes (lipoxygenase LOX, alcohol acyltransferase AAT, and alcohol dehydrogenase ADH), and fatty acids (palmitic, stearic, oleic, linoleic and linolenic acids) were assessed in Golden Delicious fruit apples (Malus domestica Borkh.) during 1 ºC storage at different atmosphere conditions. Three atmosphere conditions were used: 21 % O2 and > 1 % CO2 (Regular Atmosphere, RA), 3 % CO2 and 2 % O2 (Controlled Atmosphere, CA), and CA, with 7 d under RA conditions (CA + RA), to evaluate the effect of shorts periods under air storage. CA conditions inhibited the production of butyl acetate and hexyl acetate esters, and increased hexanol concentration. Production of the branched ester 2-methyl butyl acetate did not decrease under CA conditions. As a result of 7 d under RA, butyl acetate and hexyl acetate in CA + RA increased, mainly after one month of storage. Storage under CA conditions inhibited LOX and AAT activity at some stages whereas ADH activity increased during CA storage. LOX activity showed high correlation with production of aldehydes (r2 = 0.85) and cis-2-hexenal (r2 = 0.94), during storage of apples under CA conditions. Good correlation was found between AAT activity and total esters and butyl acetate content under CA storage of apples (r2 = 0.92 and r2 = 0.93, respectively). While most fatty acids increased in concentration during RA and CA storage, linolenic acid content decreased. No correlation between volatile compounds content and fatty acid production was found.

Production of Volatiles in Fresh‐Cut Apple: Effect of Applying Alginate Coatings Containing Linoleic Acid or Isoleucine

“…The reason for these findings could be a lack of activity of ADH enzyme, necessary for the production of hexanol from hexanal. According to Salas and others (), the activity of ADH decreases considerably after ‘Golden Delicious’ apple has been stored for 5 mo under conventional refrigeration (the time period apples were stored before being used in this study). On the other hand, it has been suggested that the low production of volatile aroma compounds of apples stored for long periods might be due to that ADH prefers fermentative processes rather than volatile production processes (Lara and others ).…”

“…This could be due to low activity of AAT enzyme. According to Salas and others (), AAT activity decreases about 50% after ‘Golden Delicious’ apples are stored under conventional refrigeration. Lara and others () also reported that storage for 6 mo induced a sharply reduction of AAT activity in ‘Mondial Gala’ apples.…”

“…Figure shows how the addition of linoleic acid did not cause an increase in butyl acetate concentration, as was expected, since butyl acetate comes from butanol and no production of butanol was observed on linoleic acid‐coated apples when compared with Alg‐Ca apples (Figure ). No production of butanol on coated apples containing linoleic acid could be due to a lack of activity of the enzyme necessary to convert butanal to butanol, namely ADH whose activity decreases about 50% after apples are stored under conventional refrigeration (Salas and others ), and which could prefer fermentative processes rather than volatile production processes (Lara and others ). Strangely, higher concentration of 1‐butanol was found on LAA at days 3, 6, and 9 (Figure ), however this compound is not produced from isoleucine.…”

“…Isoleucine can be metabolized by pyruvate decarboxylase to 2‐methylbutanal (Dickinson and others ), and by ADH to 2‐methyl butanol, which is transformed to 2‐methyl butyl acetate by AAT (Rowan and others ; Dickinson and others ). Although after 5 mo of apple storage, there is a reduction in the activity of ADH and AAT (Salas and others (), a preference of ADH and AAT for AA path way may be the reason for an increase in the concentration of 2‐methyl butanol and 2‐methyl butyl acetate. According to Rowan and others () there is a preference for AAT to produce 2‐methylbutyl esters in Red Delicious apples.…”

Evaluation of Volatilomic Fingerprint from Apple Fruits to Ciders: A Useful Tool to Find Putative Biomarkers for Each Apple Variety

“…The main precursors of VOCs in apple fruits are fatty acids that are catabolized through β-oxidation and the lipoxygenase (LOX) pathway, which produce aldehydes, alcohols, and esters. Among these, aldehydes are predominant in immature apples, whereas alcohols and esters prevail in ripe/over-ripe fruits [ 22 ]. Regarding the different investigated variables (such as apple variety, ripening stage, and yeast strain), apple variety proved to be the primary attribute influencing the quality and aroma properties of apple ciders [ 23 ].…”