Low O2 and high CO2 concentrations can be used effectively to slow respiration and retard decay, but anaerobic and C02-injurious conditions must be avoided. The objective of this research was to: 1) determine the effects of low O2 and very high-C02 on flavor quality and accumulation of fermentation products. Strawberries and blueberries were stored in 2% O2/0% CO2, 20% 02/50% CO2, 2% O2/50% CO2, and 20% 02/0% CO2 for 0, 2, 4, 6, and 8 days at 20C. A taste panel evaluated the berries at the end of each storage period and again after 2 days under ambient conditions. Ethanol was the primary fermentation product that accumulated in response to low O2 and high CO2 concentrations. However, acetaldehyde was produced preferentially in response to elevated C02 levels. The flavor quality of the strawberries and blueberries was only acceptable for 2 days for treatments containing 50% CO2. The most intense off-flavors were detected in the 2% 02/50% CO2 and 20% O2/50% CO2 samples. 50% CO2 was highly effective in preventing decay, but this concentration was too high for acceptable flavor quality for storage periods greater than 2 days.
Diana Dostal Lange and Randolph M. Beaudry
Kate M. Evans, Bruce H. Barritt, Bonnie S. Konishi, Marc A. Dilley, Lisa J. Brutcher, and Cameron P. Peace
fruit were also instrumentally evaluated for weight, soluble solids, titratable acidity, and firmness ( Table 1 ). ‘WA 5’ fruit is firm, crisp, and juicy in texture and has a balanced flavor with a slightly higher acid to sugar ratio than ‘Gala’ and
M.C. Dever, R.A. MacDonald, M.A. Cliff, and W.D. Lane
Cherry cultivars (Prunus avium L.) from the breeding program located at Agriculture and Agri-Food Canada, Research Centre, Summerland, B.C., were profiled for their sensory characteristics. Judges scored six visual attributes, five flavor/texture attributes, and the degree of liking on 10-cm anchored line scales. There were significant differences (P ≤ 0.001) in external firmness, size, and color intensity as well as differences in flesh firmness, juiciness, sweetness, sourness, and intensity of cherry flavor among the cultivars. Principal component analysis (PCA) showed the relationships among the internal sensory attributes, including a calculated sum of perceived sweetness and sourness, and the analytical values (pH, soluble solids concentration, sugar: acid ratio). Factor scores located individual cultivars on the PCA plot and provided a graphic illustration of their sensory characteristics.
Clara Pelayo, Betty Hess-Pierce, Susan E. Ebeler, and Adel A. Kader
Elevated CO2 atmospheres reduce decay and extend postharvest life based on appearance of strawberries but flavor quality may be lost faster than appearance quality. California-grown `Aromas', `Diamante,' and `Selva' strawberries were stored at 5 °C in air or 20 kPa CO2 + air for 15 days and evaluated for quality attributes, chemical changes, and flavor. In a “Preference Test”, `Selva” and `Diamante' were more preferred than `Aromas'. This may be related to their higher titratable acidity (TA), total soluble solids (TSS), the concentration of total aroma compounds, a different methyl/ethyl esters ratio, and the presence of C6 aldehydes. The postharvest life in air was 7, 9, and 9 days for `Aromas', `Diamante' and `Selva', respectively and these periods were extended by 30%, 20%, and 45% in the CO2-enriched atmosphere. There were no significant differences in TA or TSS between fruits kept in air or in air + CO2 and panelists could not detect differences in sourness and sweetness after 9 days of storage. In contrast, there was a trend for CO2-stored fruits of the three cultivars to be categorized as more aromatic, and for `Aromas' and `Selva' fruits to be described as more “strawberry like” in flavor compared to the corresponding air-stored fruits. The total aroma concentration decreased to a lesser extent in `Aromas' and `Selva' strawberries kept in air + CO2 than in those stored in air. The CO2-enriched atmosphere stimulated fermentative metabolism only in `Aromas' and `Selva'; the higher concentration of ethanol in these two cultivars favored the synthesis of ethyl esters. The total content of aroma compounds and the methyl/ethyl esters ratio may be two of the multiple factors determining the overall fruit flavor.
Dangyang Ke and Adel A. Kader
Selected cultivars of several fruit species were exposed to 0.25% or 0.02% O2 at 0, 5, or 10C for short durations to investigate the potential of these treatments as quarantine procedures for postharvest insect control. Beneficial effects of such low O2 treatments included inhibition or delay of ripening processes as indicated by reduction in respiration and ethylene production rates, retardation of skin color changes and flesh softening, and maintenance of titratable acidity. While appearance was not adversely influenced by the short-term low O2 treatments, the development of alcoholic off-flavor was the most important detrimental effect, which limited the tolerance of fresh fruits to low-O2 atmospheres. Ethanol content and flavor score of the fruits had a logarithmic relationship. The threshold ethanol concentration associated with off-flavor detection (EO) increased with SSC of the commodity at the ripe stage, and it could be estimated using the following formula (Log EO)/SSC = 0.228. Using SSC of ripe fruits and average ethanol accumulation rate per day (V) from each low O2 treatment, the tolerance limit (Tl) of fruits to low O atmospheres could be predicted as follows: Tl = EO/E = 1 00.228 SSC2/V.E
E.A. Baldwin, M.O. Nisperos-Carriedo, and M.G. Moshonas
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.
Tadahisa Higashide, Ken-ichiro Yasuba, Katsumi Suzuki, Akimasa Nakano, and Hiromi Ohmori
of fruit flavor, although we did not measure titratable acid. Detailed investigations will be required to confirm this change in fruit quality. Fig. 2. Relation between the dry matter content per fruit and the soluble solids content in fruits of six
Kil Sun Yoo, Leonard M. Pike, and Brian K. Hamilton
A simple and fast method for measuring low boiling point (LBP) volatile terpenoids in carrots (Daucus carota L.) was developed by using a direct headspace sampling technique. Seven LBP terpenoid compounds were separated with high sensitivity and consistency via gas chromatography. High boiling point terpenoids above terpinolene were not well characterizable. Standard compounds showed highly linear responses up to 10 μg.g-1, with a detection limit of 0.01 μg.g-1. We confirmed that high α- and β-pinene and/or total terpenoids contributed to harsh or oily flavors. Up to 40 samples can be analyzed in an 8-h day using this method, compared to 10 samples using previous methods.
Stanley J. Kays and Yan Wang
J.K. Collins, B.D. Bruton, and P. Perkins-Veazie
Organoleptic evaluations of shrink film-wrapped and nonwrapped musk-melon (Cucumis melo L. var. reticulates cv.. TAM Uvalde) fruit were conducted to determine changes in flavor and taste during refrigerated storage. Ripe green and yellow `TAM Uvalde' muskmelons, shrink film-wrapped in 12.7-μm high-density polyethylene film, were compared to nonwrapped melons during 21 days of storage at 4C and 90% to 95% RH. After 21 days of storage, both yellow and green shrink-wrapped melons had better appearance, less surface mold, and less vein tract browning than nonwrapped melons. However, the flavor and taste of shrink-wrapped fruit were significantly inferior to those of nonwrapped melons. Green-wrapped melons were rated poorer in taste and flavor than yellow-wrapped and nonwrapped melons after 14 days of storage. These results indicate that shrink-wrapping may enhance undesirable flavor changes in muskmelon during storage.