Search Results

You are looking at 1 - 10 of 53 items for :

  • Refine by Access: All x
Clear All
Free access

Charles F. Forney, James P. Mattheis, and Rodney K. Austin

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.

Free access

Hidemi Izumi, Alley E. Watada, and Willard Douglas

`Marathon' broccoli (Brassica oleracea L. var. italica) florets were stored in air, low O2(0.25%, 0.5%, and 1 %) or high CO2(3%,6%, and 10%) at 0, 5, and 10C. Oxygen consumption and CO2 production were reduced under low O2 or high CO2atmosphere, the reduction being greater at lower O2 and higher CO2 levels. No differences were found in ethylene production among the different atmospheres. Low O2 and high CO2 retained color of broccoli florets to about the same extent at 10C but had no effect at 0 and 5C. Development of soft rot and browning was suppressed by low O2 or high CO2, but offensive off-odor occurred in 0.25%02 at all temperatures and 0.5% O2 at 10C. These results indicate that the best O2 and CO2 levels seem to be 0.5% O2 and 10% CO2 at 0 and 5C, and 1% O2 and 10% CO2 at 10C.

Free access

Charles F. Forney

Freshly harvested heads of `Cruiser' or `Paragon' broccoli (Brassica oleracea L. Italica group) were heated by immersing in water at 42, 45, 48, 50, or 52C. Immersion times were decreased as treatment temperatures were increased and ranged from 20 to 40 minutes at 42C to 1 to 3 minutes at 52C. Control heads, dipped in 25C water for 0, 10, or 40 minutes, began to turn yellow after ≈3 days storage at 20C and 80% to 90% relative humidity. Immersion in 42C water delayed yellowing by 1 or 2 days; immersion in 45, 48, 50, or 52C prevented yellowing for ≤7 days. Water loss of broccoli during storage at 20C increased by ≤1% per day by some hot-water treatments. Immersion in hot water decreased the incidence of decay during storage at 20C. Immersion in 50 or 52C water for 2 minutes was most effective in controlling decay development. Broccoli immersed in 52C water for 3 minutes had a distinct off-odor. Control and treated broccoli held at 0C for 8 days following hot-water dips were similar in quality. Yellowing of heat-treated broccoli was inhibited when broccoli was warmed to 20C following storage at 0C. Hot-water treatments also delayed senescence at 20C when broccoli was treated following 3 weeks of storage at 0C. Immersion of broccoli in 50C water for 2 minutes was the most effective treatment for reducing yellowing and decay while not inducing off-odors or accelerating weight loss.

Free access

Yaguang Luo

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

Free access

Malkeet S. Padda and David H. Picha

sweetpotato tissue showed a rapid increase and decrease, respectively. The O 2 levels in all bags after 8 d of storage were sufficient to avoid anaerobic respiration and no visual decay, off-odors, or off-flavors developed. Previously, McConnell et al. (2005

Full access

Sharon Dea, Jeffrey K. Brecht, Maria Cecilia do Nascimento Nunes, and Elizabeth A. Baldwin

at 5 °C. In both experiments, the visual quality of mango slices was limited by progressive drying of the slice surface and development of off-odor. Moreover, in Expt. 1, the shelf life was also limited by the overall color as mango slices showed a

Free access

J.R. DeEll and P.M.A. Toivonen

When the gas concentrations of modified atmosphere packaging (MAP) become extreme for broccoli (<2 kPa O2 and >10 kPa CO2), off-odors and off-flavors may develop via anaerobic respiration, rendering it unmarketable. We recently showed that chlorophyll fluorescence decreases when broccoli switches to anaerobic behavior in MAP. The objectives of this study were to determine: 1) if chlorophyll fluorescence returns to normal levels after the package is opened and hence the broccoli is exposed to ambient air, and 2) if chlorophyll fluorescence is related to off-odors that develop. Broccoli heads were held in MAP (2 to 3 kPa O2 and >10 kPa CO2) at 0 to 1 °C for 4, 7, 14, 21, or 28 days, and then 5 days in ambient air at 0 to 1 °C. Chlorophyll fluorescence of the broccoli decreased dramatically in MAP, and remained low during the subsequent 5 days in ambient air. Similarly, off-odors became worse and acetaldehyde, ethanol, and ethyl acetate increased in the broccoli with time in MAP. However, these compounds slightly decreased during the subsequent 5 days of storage in ambient air. Chlorophyll fluorescence parameters correlated negatively with off-odor development and acetaldehyde, ethanol, and ethyl acetate levels in the tissue.

Free access

Barbara J. Daniels-Lake, Robert K. Prange, Sonia O. Gaul, Kenneth B. McRae, Roberto de Antueno, and David McLachlan

” flavor/“offodor of 473 mol·kg −1 TCA in odorless mineral oil. Application of γ-cyclohexane hexachloride (γ-CHC) to the fields before potato production is indicated by filled symbols; open symbols indicate tubers produced without γ-CHC. Acceptability

Free access

Ji Gang Kim, Yaguang Luo, Robert A. Saftner, and Kenneth C. Gross

Fresh-cut tissues are subjected to severe injury during preparation that leads to increased respiratory activity and quality deterioration. Modified atmosphere packaging (MAP) has been used to maintain quality of fresh-cut produce, but O2 depletion and excessive CO2 accumulation can be injurious. This study was conducted to evaluate the effect of delayed packaging and MAP using two different oxygen transmission rate (OTR) films on quality maintenance and shelf stability of fresh-cut romaine lettuce (Lactuca sativa L.). Romaine lettuce leaves were cut, washed, dried, and placed for 0, 4, 8, and 12 hours at 5 °C in ambient air before packaging. Fresh-cut samples were placed into packages prepared from films having OTRs of 8.0 and 16.6 pmol·s-1·m-2·Pa-1, flushed with N2 to reach an initial headspace O2 level of 1.5 kPa O2, and stored at 5 °C for up to 14 days. Delayed packaging affected gas composition, fermentative volatile production, off-odor development, color, CO2 injury, and tissue electrolyte leakage. With increasing delay before packaging, fermentative volatile production, off-odor development, and CO2 injury progressively decreased and discoloration increased. The modified atmospheres obtained with 16.6 OTR film increased discoloration when present, and generally had less off-odor development and CO2 injury compared to MAP with 8.0 OTR film. Delayed packaging affected overall quality of fresh-cut romaine lettuce packaged with both films. A 12-hour delayed packaging into packages prepared from 8.0 OTR film maintained quality by inhibiting CO2 injury, off-odor development, and tissue electrolyte leakage. However, an 8-hour delayed packaging into packages prepared from 16.6 OTR film was better at maintaining the quality of fresh-cut romaine lettuce at 5 °C for 14 days. The results indicated that delayed packaging could be an alternative method to optimize or balance package O2 during suboptimal OTR film packaging conditions.

Free access

Hidemi Izumi, Tetsuya Nakatani, and Hiroki Ogikubo

`Sunbest' spinach leaves were stored in air or controlled atmosphere (CA) containing 3%, 6%, and 10% CO2 combined with 0.5% O2 at 0, 10 and 20 °C. Carbon dioxide production and O2 consumption of spinach leaves decreased in CA by about 50%, 40%, and 65% relative to those in air at 0, 10 and 20 °C, respectively. The rates in the different CA were similar. The respiratory quotient (RQ) of spinach leaves held in CA was slightly higher than that held in air at 0 and 20 °C. CA inhibited the growth of aerobic mesophilic bacteria and lactic acid bacteria at all temperatures, with the inhibition being greater in 6% or 10% CO2 with 0.5% O2. The ascorbic acid content at the end of storage was higher in spinach leaves held in air than in CA at all temperatures except 10% CO2 with 0.5% O2 at 20 °C. A slight or no off-odor was emitted by all spinach leaves. At 20 °C, spinach leaves held in 6% and 10% CO2 with 0.5% O2 developed more off-odor than those in air. These results indicate that the CA of 3%-10% CO2 and 0.5% O2 was beneficial in reducing respiration rate and microbial growth of spinach leaves at 0, 10, and 20 °C but accelerated ascorbic acid loss at all temperatures and induced off-odor at 20 °C.