Titre :
|
Effects of freezing rate on astringency reduction in persimmon during and after thawing
|
Auteurs :
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S. Taira ;
M. Ono ;
M. Otsuki
|
Type de document :
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article/chapitre/communication
|
Année de publication :
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1998
|
Format :
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p. 317-324
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Langues:
|
= Anglais
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Catégories :
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INDUSTRIE AGRO-ALIMENTAIRE
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Mots-clés:
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FRUIT
;
CONGELATION
;
DECONGELATION
;
VITESSE DE CONGELATION
;
QUALITE DES ALIMENTS
|
Résumé :
|
We compared the reduction of astringency in the flesh of persimmon fruit (Diospyros kaki Thunb. Cv. 'Hiratane-nashi') either slowly frozen in a conventional freezer or rapidly frozen with liquid nitrogen, during and after thawing. Astringency and concentration of soluble tannins in flesh frozen by either method had decreased little by the start of thawing. In slowly frozen flesh, soluble tannins decreased greatly during thawing, and the thawed flesh was almost non-astringent. However, rapidly frozen flesh was still astringent after being thawed. Astringency reduction in frozen and thawed persimmon flesh is probably not related to changes in pectic substances, which changed little during and after thawing, whatever the mode of freezing. Microscopic observations suggested that these differences may be related to the degree of damage that occurred in flesh cell walls and plasma membranes during freezing. Soluble tannins, released from tannin cells during thawing, became insoluble on contact with fragments of cell walls and plasma membranes. The process of tannin insolubilization was greatest for slowly frozen flesh.
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Source :
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Postharvest Biology and Technology, vol.14
|