- The effects of mold level (Botrytis cinerea), processing method (fresh, individually quick frozen (IQF), frozen sugared sliced (FSS), freeze dried (FD), canned, and preserves), and maturity (underripe, normal, and overripe) and strawberry volatiles were analyzed by gas liquid chromatography (GLC) using on-column entrainment of headspace volatiles in aqueous extracts. Computerized analyses were used to calculate peak areas and to perform analyses of variance comparing the area of each peak for different samples. Peaks varying significantly (P < 0.05) with processing method, maturity, and mold count were collected on Porapak Q columns, transferred to GLC columns, and identified by coupled GLC-mass spectrometry and by GLC retention times.
All volatiles whose peak areas changed significantly with mold level (P < 0.05) decreased as mold level increased. These volatiles were as follows: n-propionic acid, n-butyric acid, acetaldehyde, isobutyraldehyde, methyl acetate, 1, 1-diethoxymethane, 1,1-diethoxyethane, acetophenone, propiophenone, 1-phenyl-1, 2-propanedione, diethyltoluene, and one unknown. Neither ethanol nor diacetyl changed significantly with mold level.
Volatiles increasing significantly on processing were found in canned fruit and preserves. These were dimethyl sulfide, benzaldehyde, furfural, and 1-propanethiol. In canned fruit and preserves 5-(hydroxymethyl)-2-furfural was newly formed. Many compounds (acetals, acids, alcohols, aldehydes, esters, ketones, and hydrocarbons) decreased significantly in level on processing; all were identified. Numbers of compounds decreasing significantly with each process were as follows: IQF, five lower-boiling compounds; FSS, two lower-boiling compounds; FD, 37 compounds; canned, eight compounds; and preserves, 29 compounds.
In general most compounds varying significantly (P < 0. 05) with maturity increased. No new compounds were formed on ripening, and no compounds completely disappeared with ripening. The compounds varying significantly with maturity were esters (methyl acetate; ethyl formate, acetate, propionate, and butyrate; n-pentyl _n-hexanoate; β-phenylethyl acetate; cis-3-hexen- 1-yl hexanoate; and benzylacetate), aldehydes (acetaldehyde, isobutyraldehyde, benzaldehyde, and ethylbenzaldehyde), acetals (1, 1-dimethoxymethane, 1, 1-diethoxymethane, 1, 1-diethoxyethane, and 1, 1-diethoxyoctane), acids (propionic, n.- butyric, and isobutyric), aromatic ketones (acetophenone, propiophenone, propylphenyl ketone, and 3-phenylpropan-2-one), ethanol, and one unknown.
These results would not seem to encourage use of this technique for monitoring mold levels in strawberries.