The volatile components have been isolated from guava puree (Psidium guajara, L.) and separated by gas-liquid chromatography. The separated constituents were directed into a mass spectrometer via a molecular separator and identifications made from the mass spectral patterns. A total of 22 components have been identified with cis-3-hexen-1-01, hexanol, and hexanal predominating. Several Brekke, and Donald J. Stern aromatic compounds have been identified with methyl benzoate, P-phenethyl acetate, and methyl cinnamate comprising the bulk of this class. Some terpenes and terpene alcohols have also been identified. Several constituents have been classified as sesquiterpenes (m.w. = 204), but specific identifications have not been possible, with the exception of caryophylene.lthough the investigation of the volatile constituents in fruits has been progressing at a phenomenal rate A during the past few years, and especially with the advent of GC-MS combinations. relatively little attention has been given to the tropical fruits. The guava (Psidium guajaca, L.) is an attractive fruit possessing many desirable characteristics. It has a rather delicate pink color and makes excellent juice, jam, jellies, etc. Because of this, the fruit is rapidly assuming greater economic importance. Guava is widely distributed in Hawaii (below 3000 ft), being introduced in the 1790's presumably from tropical America.One of the first reports concerned with the volatile constituents was by Kunishi and Seale (1961) at the University of Hawaii. They made some preliminary studies on guava and found the puree to contain 49 ppm of oil. The oil, by infrared spectroscopy, contained neither carbonyl nor carbon-carbon double bonds; however it gave positive bromine and permanganate tests. No specific identifications were made.In 1968 and 1969 a group of Indian workers (Pattabhiraman ef a / . ) reported the isolation and partial characterization of the volatile material in guava. They found that the guava oil was not adversely affected by mild heating. Also, the isolated oil was subjected to thin-layer chromatography and a spot, detected by vanilla-sulfuric acid and 2,4-dinitrophenylhydrazine, had the characteristic aroma of guava. The material was also reduced by lithium aluminum hydride. These data, along with the ultraviolet and infrared spectra. suggested to them that the aroma constituent(s) was of the carbonyl and ester type. Although the infrared spectrum of the crude guava oil showed no hydroxyl absorption, a 3,5-dinitrobenzoate derivative was made which showed three spots by thin-layer chromatography. While several components were shown to be present, no specific identifications were made. EXPERIMENTAL Guava Puree. Fruits of the Beaumont variety produced in Hawaii were sorted, washed, then comminuted with a Fitzmill, Calif. 94710 using a 4-B screen. The milled fruit was passed through a paddle pulper (0.045 screen) to remove seeds, then passed through a paddle finisher (0.020 screen) to remove stone cells.The puree was then placed in 30-lb can...

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Starches in the juices of yellow passion fruit, Passiflora edulis f. flavicarpa, and purple passion fruit, P. edulis f. edulis, were isolated and characterized. Starch granule sizes for the yellow variety (7.8 μm) and purple variety (6.4 μm) were similar. Gelation temperature ranges for the yellow variety (58.5–67.0 ° c) and purple variety (58.5–66.5 ° C) were also similar. The amylose content was slightly higher in the yellow variety (8.7%) than in the purple variety (5.8%). Viscosity differences between juices of the two varieties after treatment with heat and α‐amylase were attributed to differences in pH and starch content between the yellow variety (pH 2.8, 0.06% starch) and the purple variety (pH 4.2, 0.74% starch). α‐amylase was effective in reducing the viscosity of passion fruit juice in which the starches are gelatinized.