Broccoli (Brassica oleracea L., ltalica Group) produces severe off-odors when it is stored under anaerobic conditions which can develop in modified atmosphere packages. The compounds responsible for these off-odors, which render the broccoli unmarketable, were produced after sealing 50 g of fresh broccoli florets in glass pint jars held at 15C. Twenty-four hours after sealing oxygen concentration dropped to around 0.5% and remained at this concentration for 6 days. Volatile compounds found in the head space of the jars were identified using gas chromatography with flame photometric and mass spectroscopic detection. Volatile compounds produced were identified as methanethiol, hydrogen sulfide, dimethyl disulfide, acetaldehyde, acetone, ethanol, and ethyl acetate. Methanethiol was detected 48 hours after sealing and appears through olfactory evaluation to be the primary compound responsible for the objectionable odor.
Charles F. Forney, James P. Mattheis, and Rodney K. Austin
Elhadi M. Yahia
The effectiveness of some poststorage treatments in enhancing the flavor components of low-ethylene controlled-atmosphere (LCA) stored `McIntosh' apples (Malus domestica Borkh.) was investigated. Fruits were stored for 9 months in LCA at 3.3C and then exposed to air at 20C and to air, simulated LCA, 100% O2, or light at 3.3C for up to 4 weeks. Respiration and ethylene production indicated that apples were still in the early stage of ripening after 9 months of storage in LCA. Gas chromatographic analysis for 13 odor-active volatiles revealed the presence of eight. Air at 20C after LCA significantly increased the production of some odor volatiles, while light for up to 3 weeks only slightly increased their concentration. Poststorage exposure to air or 100% O2 at 3.3C for up to 4 weeks was not effective in enhancing volatile formation.
Jennifer R. DeEll and Peter M.A. Toivonen
The objective of this study was to determine if chlorophyll fluorescence could be used as an indicator of anaerobic respiration in broccoli (Brassica oleracea L., Italica group) during modified-atmosphere packaging (MAP). Two types of packages were used, PD-941 bags, which provided optimum MAP conditions for broccoli (≈3 kPa O2 plus 5 kPa CO2), and PD-961EZ bags, which allowed the CO2 to accumulate (≈11 kPa CO2). After 28 days in MAP at 1 °C, the broccoli from both types of bag had similar appearances and weight losses. However, broccoli held in the PD-961EZ bags had developed slight to moderate alcoholic off-odors and had higher ethanol, acetaldehyde, and ethyl acetate content, as compared with broccoli in PD-941 bags. Chlorophyll fluorescence parameters (Fv/Fm, T1/2, Fmd, and ΦPSII) were lower for broccoli held in the PD-961EZ bags than in PD-941 bags, and these differences increased with storage duration. These results indicate that chlorophyll fluorescence is a reliable, rapid, nondestructive indicator of broccoli quality during MAP, and that it could be used to determine if broccoli has developed off-odors without opening the bag and disrupting the package atmosphere.
Jyh-Bin Sun, Ray F. Severson, and Stanley J. Kays
We describe a relatively simple collection procedure for quantifying volatiles in baked sweetpotato [Ipomoea batatas (L.) Lam.]. Volatiles formed during baking `Jewel' and `Centennial' sweetpotatoes at 204C were purged from a baking vessel with He or a HeO2 mixture, collected in cold methylene chloride, and reduced in volume using a Kuderna-Danish concentrator. Volatile components were quantified by capillary gas chromatography and characterized using gas chromatographic-mass spectrometer analysis. Quantitatively, the major components were identified as 2-furaldehyde; 2-furanmethanol; benzaldehyde; 5-methyl-2-furfural; phenylacetaldehyde; 3-hydroxy-2-methyl-4 H -pyran-4-one; 2,3-dihydro-3,5-dihydroxy-6-methyl-4 H- pyran-4-one; and 5-hydroxy-methyl-2-furancarboxaldehyde. Some quantitatively minor compounds were also identified. The volatile collection system is reproducible for quantitative comparisons among breeding lines.
Steven F. Vaughn and Gayland F. Spencer
The shelf-life of strawberries and raspberries is limited primarily due to losses from fungal decay. During ripening, these fruits release numerous volatile compounds, some of which have been shown to have antifungal activities. We examined fifteen volatiles released by both fruits for the prevention of postharvest fungal decay. Benzaldehyde, 1-hexanol and 2-nonanone completely inhibited all fungal growth on fruit at gas headspace concentrations of 0.1 μl/ml, while causing little damage to the fruit. However, greater levels of these compounds, although completely inhibiting fungi, generally caused some fruit damage. Headspace concentrations of these compounds at 0.04 μl/ml or greater completely inhibited the growth of Botrytis cinerea and Alternaria alternata in culture but higher levels were required to inhibit Colletotrichum gloeosporoides and Rhizopus stolonifer. These results suggest that these compounds could be used to effectively prevent fungal decay if constant, low levels could be maintained in the headspace surrounding the fruit.
Stanley J. Kays, Jason Hatch, and Dong Sik Yang
Selection emphasis on cyme size and flower color of Heliotropium arborescens L. has led to cultivars with diminished floral fragrance. As a preliminary inquiry into the fragrance chemistry of the species, we identified 41 volatile compounds emanating from the flowers of 'Marine' via isolation (Tenax trapping) and gas chromatography–mass spectrometry. The majority of the volatile compounds emanating from the flowers were terpenes (camphene, p-cymene, δ-3-carene, α-humulene, δ-1-limonene, linalool, (E)-β-ocimene, α-pinene, and β-thujone), benzenoids of which benzaldehyde was the most abundant, aldehydes (decanal, heptanal, nonanal and octanal), and hydrocarbons (decane, heneicosane, heptadecane, hexadecane, nonadecane, nonane, octadecane, tetradecane, tridecane and undecane) along with a cross-section of other compounds. Subsequent identification and quantification of critical ordorants will facilitate selecting new cultivars with quantitative and qualitative improvements in fragrance.
Barbara J. Daniels-Lake, Robert K. Prange, Sonia O. Gaul, Kenneth B. McRae, Roberto de Antueno, and David McLachlan
In 2001, several million kilograms of fresh and processed potato products from the Annapolis Valley of Nova Scotia, Canada (i.e., most of the local crop) was rejected by consumers because of a strong “musty” “off” flavor and odor (OFO). As a
R. Porat, B. Weiss, I. Zipori, and A. Dag
fruit exude a strong odor, and are rich in volatile aroma compounds ( Steinhaus et al., 2008 ). The main obstacles to commercial export and marketing of fresh ripe guava are that they are highly perishable and emit a strong odor that is not always
three trained personnel. The samples were coded with three-digit numbers to mask the treatment identity in an effort to minimize the test subjectivity and to ensure test accuracy. Off-odor was evaluated immediately after opening the packages and scored
İbrahim Kahramanoğlu and Chunpeng Wan
studies, in addition to weight loss and shriveling, visual quality, abnormal odor, decay incidence, ascorbic acid (AsA) (vitamin C), respiration rate, chlorophyll content, and carotenoids contents were also determined. Visual quality was assessed according