No abstract

Tomato (Lycopersicon esculentum Mill.) fruit, cvs. Sunny and Solar Set, were analyzed at five ripening stages for ethylene and CO2 production. Homogenates from the same fruit were prepared for determination of color, flavor volatiles, sugars, and organic acids. Changes in the levels of these compounds were compared to the pattern of climacteric ethylene production. Of the flavor volatiles measured, only eugenol decreased during ripening in both cultivars and 1-penten-3-one in `Sunny' tomatoes. Ethanol and trans-2-trans- 4-decadienal levels showed no change or fluctuated as the fruit ripened while all other volatiles measured (cis- 3-hexenol, acetaldehyde, cis- 3-hexenal, trans-2- hexenal, hexenal acetone, 6-methyl-5 -hepten-2-one, geranylacetone, and 2-isobutylthiazole) increased in concentration, peaking in the turning, pink, or red stage of maturity. Synthesis of some volatile compounds occurred simultaneously with that of climacteric ethylene, CO2 and lycopene production. `Solar Set' fruit exhibited higher levels than `Sunny' of all flavor components except ethanol and hexanal in the red stage. There were no differences in organic acid levels between the cultivars; however, `Solar Set' had higher levels of sugars. Changes in acid and sugar levels showed no temporal relationship to climacteric ethylene or CO2 production.

Sixteen unpasteurized juices and one pasteurized juice from mandarin and mandarin hybrid fruit were analyzed by headspace gas chromatography (HSGC), and 42 volatile constituents were quantified in each sample. Fifteen of the mandarin juice samples had relatively low levels of volatile constituents believed important to citrus flavor when compared to comparable values in orange. The quantities were used for comparison with unpasteurized orange juices using data similarly obtained in an earlier study by HSGC. Multivariate analysis separated the mandarin and orange samples, when the first three principal components were displayed graphically. Keywords: Headspace gas chromatography; principal component analysis; fruit juice composition; Citrus reticulata

A rapid GC method was developed to analyze the headspace composition of cultivar Kent, Keitt, and Tommy Atkins mango homogenates. Factors affecting quantitative results were also studied. Of the 13 volatile compounds identified, 9 were terpene hydrocarbons:  α-pinene, β-pinene, 3-carene, myrcene, limonene, p-cymene, terpinolene, α-copaene, and caryophyllene. Volatile concentrations were quantified using peak height calibration curves (peak height vs concentration). Linear relationships were derived for all compounds except caryophyllene. Rate of peak height increase was slower at caryophyllene levels <2 ppm than at those ≥2 ppm. Volatile levels increased as homogenate was diluted with up to 50% water. Addition of CaCl2 during blending, to inhibit degradative enzymes, induced gelation, which resulted in decreased volatile concentrations in the headspace. Sonicating gelled homogenate resulted in partial liquefaction and an increase in headspace volatiles. These results indicate that significant interactions between mango pulp and volatile compounds occur and, depending on sample preparation method, can affect quantitative results. Keywords: Flavor; gelation; hydrocarbons; terpenes