Volatile components and aroma active compounds in aqueous essence and fresh pink guava fruit puree (Psidium guajava L.) by GC-MS and multidimensional GC/GC-O.

Characterization of the aromatic profile in commercial guava essence and fresh fruit puree by GC-MS yielded a total of 51 components quantified. Commercial essence was characterized to present a volatile profile rich in components with low molecular weight, especially alcohols, esters, and aldehydes, whereas in the fresh fruit puree terpenic hydrocarbons and 3-hydroxy-2-butanone were the most abundant components. In the olfactometric analyses totals of 43 and 48 aroma active components were detected by the panelists in commercial essence and fruit puree, respectively. New components were described for the first time as active aromatic constituents in pink guava fruit (3-penten-2-ol and 2-butenyl acetate). Principal differences between the aroma of the commercial guava essence and the fresh fruit puree could be related to acetic acid, 3-hydroxy-2-butanone, 3-methyl-1-butanol, 2,3-butanediol, 3-methylbutanoic acid, (Z)-3-hexen-1-ol, 6-methyl-5-hepten-2-one, limonene, octanol, ethyl octanoate, 3-phenylpropanol, cinnamyl alcohol, alpha-copaene, and an unknown component. (E)-2-Hexenal seems to be more significant to the aroma of the commercial essence than of the fresh fruit puree.

Aroma active components in aqueous kiwi fruit essence and kiwi fruit puree by GC-MS and multidimensional GC/GC-O.

Gas chromatography-mass spectrometry (GC-MS) and multidimensional gas chromatography olfactometry (GC/GC-O) were utilized to study the aroma profile and the aroma active components of commercial kiwi essence and the initial fresh fruit puree. Totals of 29 and 33 components were identified and quantified in the essence and the puree, respectively. Ten components were quantified for the first time as constituents of the kiwi fruit including 3-penten-2-ol, 3-hydroxy-2-butanone, 3-methyl-2-butenal, 2-hexanol, nonanal, 3-methyl-1-butanol, 2-methyl-1-butanol, 3-methyl-2-butanone, 3-methyl 3-buten-2-one, and octane. Analysis of these samples by multidimensional gas chromatography-olfactometry (GC-O) allowed for the identification of >80% of the aroma active components present at level traces in this fruit. A total of 35 components appear to contribute to the aroma of kiwi fresh puree and its aqueous essence. Components described for the first time as constituents of the aroma profile in this fruit were 2-ethylfuran, 3-methyl-1-butanol, 2-cyclohexen-1-one, (E,E)-2,6-nonadienal, diethyl succinate, and hexyl hexanoate.

Bacterial Count from Bovine Carcasses as an Indicator of Hygiene at Slaughtering Places: A Proposal for Sampling.

A sampling technique by which the whole carcass is rubbed with a polyurethane sponge was used to study bacterial status on 523 beef carcasses at six different slaughterhouses over four different years. Although some abattoirs were differentiated based upon the psychrotroph counts from their carcasses, effects on counts of visits and season of sample taking, as well as interaction year x abattoir found at the other plants were large enough to mask the abattoir effect. Mesophile counts were not consistent enough to discriminate abattoirs, while, Enterobacteria, total and fecal coliforms, and Staphylococcus aureus coagulase-positive organisms showed very low counts and did not set apart differences. A guideline to monitor beef carcass hygiene and indirectely the hygiene of the slaughtering practices through the psychrotroph counts is proposed. A two-kinds sampling plan is suggested with "right-incorrect" as levels of hygiene. A sample unit (n) of 10, an acceptance number of contaminated carcasses (c) of 3, and a count limit (m) of 103 CFU/cm2 are proposed. Under this guideline, a lot of carcasses will be deemed as hygiene lacking when 4 or more, out of 10 carcasses, yield counts of 103 CFU/cm2 or higher.