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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.
Frost tolerance of flower buds is one of the most important characteristics of strawberry cultivars that produce fruit early or very early in the season. The objective of this study was to evaluate chlorophyll fluorescence (CF) as a suitable rapid method to assess spring frost injury of strawberry flowers. More specifically, to determine if there was a relationship between a decrease in CF and the appearance of visual symptoms (visual expression of necrosis (VEN) based on the amount of dark, damaged, and/or water soaked tissue of the pistil) due to frost. Sixty-six strawberry genotypes with varying levels of chilling susceptibility were used. The plants were grown in a greenhouse under a 16-h light period at 20-22 °C during the daytime and 16-18 °C at night. For the CF and VEN measurements, the plants were stored at -3 °C for 24 h followed by 24 h in the greenhouse. The CF measurements were made on dark-adapted tissue, using the Fv/Fm test of an OS-500 modulated fluorometer. For the VEN method, the flowers which had dark, damaged, and/or water soaked pistils were counted. The results showed that variable fluorescence (Fv) decreased as the temperature was lowered. The spring frost resistant cultivars maintained Fv at a stable level and had a smaller regression slope (ß1), whereas the susceptible cultivars showed a very dramatic decrease in Fv. The CF method gave results that correlated with the VEN results. The strong relationship between chilling tolerance determined via visual and florescence techniques supports the use of CF in selecting resistant spring frost selections in a breeding program. The use of CF will allow the breeder not only to select for spring frost-resistant selections independently of environmental changes, but also to select frost resistant seedlings prior to planting in the field.
The objectives of the Québec apple breeding program are to develop hardy and disease-resistant varieties for the production of juice and cider and/or varieties with an excellent fruit quality and long shelf-life. Almost 90% of the research in apple breeding is funded by a Partnership Program, in which the partners cover ≈50% of the research costs. The short-term objectives of the program are to evaluate the existing genotypes at the AAFC Frelighsburg sub-station and name worthy selections, remove unworthy material, and transfer potentially interesting genotypes to other AAFC research stations for further evaluations. Three selections—SJC7713-1, SJC686-1, and O-5410—are very hardy, scab-resistant, and have good yields of pleasantly flavored fruit, which can be stored long-term while retaining good quality. Selections SJCA14R3A108 and SJCA36R7A87 are not scab-resistant, but they are hardy, and the fruit have an excellent flavor, store very well for >5 months, and have a flesh that does not darken after cutting. The above selections are currently being evaluated for use by commercial growers. Selections SJC7172-1 and SJC7911-1, along with four crabapple genotypes, are of potential interest to home gardeners.
One of the major problems affecting apple trees in Eastern Canada is low temperature injury during the winter and spring. Although there have been many studies on the cold hardiness of apple trees, no survey has been done on winter injury in Québec orchards. A survey was conducted in 1995/1996 to identify factors responsible for apple tree mortality during the winter of 1993/1994 in Québec. Three-hundred-thirty (330) apple orchards were visited and information on more than 50 characteristics were evaluated via a questionnaire; including hardiness, end use, shelf-life, etc. A full report is available at http://www.pgris.com . A large diversity of cultivars and rootstocks was observed in the Québec orchards, and thus a database was created containing information for all cultivars evaluated and the collected agronomic characteristics. Some of the more important information, such as hardiness, end use, shelf-life, scab resistance, etc., along with 265 apple images, were put together as a poster. A copy of this poster is available from http://www.pgris.com .
The objective of this research was to evaluate the effects of vacuum cooling and temperature on the quality and storage life of mung bean sprouts (Vigna radiata L. Wilczek). Sprouts in micro-perforated bags were either not precooled or vacuum cooled to 9, 6, or 3 °C, and stored for 7 days at 1, 3, or 6 °C. Vacuum-cooled bean sprouts lost more weight than sprouts not precooled, and the weight loss was greater when the sprouts were cooled to lower temperatures. However, the total loss never exceeded 5% and no apparent signs of shrivel were observed. Vacuum cooling resulted in greater product freshness after 4 days of storage, but the effect was nonsignificant after 7 days. Storage temperature had greater influence on bean sprout quality than did cooling temperature, with greater freshness and whiter hypocotyls at the lower temperatures. However, blackening of cotyledons increased as the storage temperature decreased.