Abstract:

In this research study, we determined the effect of hot-air drying on three functional components (polyphenols,
flavonoids and triterpene acids) and volatile components of loquat peel. Fresh samples of loquat peel were hot-air dried 60 ℃
to a moisture of 9%–10% to investigate changes in the contents of functional components before and after the drying
process. The identification and quantitation of volatile components by using headspace solid phase microextraction coupled
with gas chromatography-mass spectrometry (HS-SPME-GC-MS). Results illustrated that the contents of polyphenols and
flavonoids in dried loquat peel were significantly lower than in fresh loquat peel (P < 0.05), which were (37.94 ± 0.84) and
(19.29±0.76) mg/g vs. (63.66 ± 1.68) and (56.78 ± 1.44) mg/g, respectively. On the other hand, no significant change in
triterpene acids was noted. Totally, 35 volatile compounds were detected in fresh loquat peel, mainly aldehydes, esters,
ketones, which were dominated by hexanal (19.79%) and trans-2-hexenal (26.59%). In comparison with fresh loquat
peel, hot-air drying resulted in the formation of new volatiles as indicated by increasing the number of volatiles identified
to 73, which mainly included aldehydes, esters and ketones. Twenty-one volatile compounds were common to both
samples. Nonanal (31.47%) was the most dominant volatile of the dried sample, followed by β-cyclocitral, β-ionone,
dihydroactinidiolide and decanal, which altogether contributed to the distinct aroma of the dried loquat peel.

Key words: loquat peel, hot-air drying, polyphenol, flavonoid, triterpene acid, volatile components