University of California

For Abstracts

Exposure of Fresh-cut Leafy Greens to Abusive Temperatures During Transit and Retail Storage and Display

W. Brown (Cal Poly, San Luis Obispo) K. Vorst (Iowa State University) (L. Gorman Cal Poly, San Luis Obispo) S. Steinmaus (Cal Poly, San Luis Obispo) and E. Ryser (Michigan State University)


There have been very limited time and temperature profiles published for the U.S. indicating the conditions experienced by fresh-cut, bagged leafy greens during transport and distribution. The objective of this study was to monitor and fully characterize temperatures during the transport, and retail storage and display, of fresh-cut leafy greens. For the transportation studies, a total of sixteen shipments were monitored for trailer temperature. Shipments were from Salinas, CA or Yuma, AZ and, in most cases, were cross-country. Twenty-four or thirty temperature loggers were placed on six pallets and along the sidewalls during the loading of each trailer. In five of the sixteen shipments, an additional sensor with probe was placed on each monitored stack and the probe was inserted 24 inches into the center of the stack. For the retail studies, five major grocery chains participated in the study and stores were monitored in San Luis Obispo, California; Las Vegas, Nevada; Wichita, Kansa; Columbus, Ohio; Atlanta, Georgia, and Philadelphia, Pennsylvania. Temperature recorders were placed in open-front display-cases and were attached every 4 feet and at 5 levels within the cases. Sensors were also placed in the holding room located at each store’s receiving dock. Data were analyzed for the effect of location within a trailer, display case or holding room, on a pass/fail basis where any sensor in a trailer recording temperatures above 5 degrees C subjected the load to rejection, and for duration of abuse above 5, 7.2 or 10 degrees C in a trailer, display case or holding room.

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Fresh-cut Product Quality and Temperature Management

Jeffrey K. Brecht (University of Florida)

Temperature history of whole products used to prepare fresh-cut products is important since tissue aging, respiration rate, and compositional changes are all temperature-responsive processes. Thus, the quality and potential shelf life of fresh-cut products can be compromised when the products are prepared from whole products that are not fresh or have not been handled under ideal conditions. Temperature management during preparation and handling of fresh-cut products is critical for maintaining quality. Even small temperature variations can result in important quality differences. A comparison of several fresh-cut vegetables and fruits held at 1.1, 2.8 or 4.4 degrees C for up to 16 days or until the product was judged to be unacceptable resulted in significant differences in appearance and composition. Quality of all fresh-cut products is best when temperature is maintained near 0 degrees C irrespective of whether the corresponding whole product is chilling sensitive. Maintaining temperature uniformity during transportation is an issue that may have negative consequences for fresh-cut product quality. Temperature mapping during shipping has shown that non-uniformity may develop due to equipment limitations in truck trailers that can allow temperature zones to develop, or magnify temperature differences that existed prior to trailer loading. Temperatures of fresh-cut products in refrigerated retail display cases have been found to vary greatly – not only among different displays, but also within the same display due to poor equipment design and product stacking procedures. Interaction between fresh-cut product temperature variability and modified atmosphere packaging design and performance also impacts quality.

Maintenance of fresh fruit quality in summer-bearing strawberry utilizing subzero nonfreezing storage and 1-MCP postharvest treatment

Takashi Suzuki (Hokkaido Univ.), Ryosuke Shimaoka (Hokkaido Univ.), Hanako Shimura (Hokkaido Univ.), Hirotaka Sakakibara (Rohm & Haas Japan Inc.), Mitsuko Ukai (Hokkaido Univ. of Education)

Cultivation of ever-bearing strawberry in summer-fall season utilizing plastic film greenhouse is increasing in northern region of Japan. However, greenhouse production can result in an unstable fruit supply to the market. To prolong shelf life of the fruits, usually less than a week at 5 degree C, effects of subzero nonfreezing storage and 1-MCP postharvest treatment on keeping quality of the fruits were investigated. Fruits of ‘Pechika Santa’ and ‘Pechika Pure’ harvested in summer, 2012 and 2013 were used for experiments. Subzero nonfreezing storage: fruits in lidded 1L-glass bottles were kept at -0.5 degree C in a programmable freezing chamber. In the preliminary tests the freezing temperature of the fruits was found to be about -2.0 degree C. 1-MCP postharvest treatment: fruits were kept in atmosphere containing 10 ppm 1-MCP for the first 24 h during storage at 5 degree C. Changes in quality of the fruits during storage were evaluated and compared with that of the fruits conventionally stored at 5 degree C. Indices of fruit quality were as follows: surface color (chroma meter); hardness (rheometer); degree of rot; sugar content (HPLC); % water; % frozen fruits. As a result varietal differences were confirmed in both methods. Hardness and color of ‘Pechika Pure’ fruits stored at -0.5 degree C was maintained without freezing for 28 days after harvest. The shelf life was also prolonged by 1-MCP treatment, but the effect was weaker than that of subzero nonfreezing storage.

Modeling ammonia accumulation and color changes of arugula leaves in relation to temperature, storage time and cultivar

Leonarda Mastrandea (Department of Science of Agriculture, Food and Environment, University of Foggia, Italy), Maria Luisa Amodio (Department of Science of Agriculture, Food and Environment, University of Foggia, Italy), and Marita Cantwell (Dept. Plant Sciences, UC Davis, Davis, CA 95616 USA)

Leafy greens produce ammonia as stressful conditions occur during postharvest handling. The objective of this study was to understand the relationship between ammonia accumulation and color variation of rocket or arugula leaves in relation to cultivar and storage temperature. Leaves of Five cultivars (Bellezia, Grazia, Letizia, Tricia, Wild Thing) were washed, centrifuged, placed in unsealed plastic bags, and stored at 0, 5 or 10 degrees C for 28, 20 and 12 days, respectively. Visual quality, color (hue angle) and ammonia accumulation were monitored periodically. Ammonia increased from 11-15 µg/g FW to 150-220 at 0 degrees C, 340-450 at 5 degrees C and to >590 µg/g FW at 10 degrees C at the end of storage-life. While there were some differences among cultivars, temperature played the major role in ammonia accumulation. Color varied due to leaf yellowing which increased with increasing temperature. Both Hue angle and ammonia changes were fitted with traditional (first and 0 order kinetics) and Weibullian models, with the latter explaining a higher percentage of the variance of experimental data. Moreover, considering that time was the common variable between the 2 kinetics, a new mathematical equation describing ammonia versus Hue for each cultivar/temperature of storage was obtained. In all cases a good correlation was obtained between ammonia and color change with more accurate results at 5 and 10 degrees C, since color at 0 degrees C was stable. These results demonstrate that ammonia may be a good indicator of senescence in Arugula since it correlated well to color change with storage temperature and storage time.

Quality Changes in Fresh-peeled Garlic Cloves in Relation to Storage Temperatures and Atmospheres

Fabio Tanamati (Faculdade de Ciências Agronômicas, Universidade Estadual Paulista Julio de Mesquita Filho, Botucatu, Brasil), Gyunghoon Hong (Mann Lab, Dept. Plant Sciences, University of California, Davis CA 95616), and Marita Cantwell (Mann Lab, Dept. Plant Sciences, University of California, Davis CA 95616)

Fresh-peeled garlic is an increasingly important product for foodservice and retail markets. Two storage tests were conducted using garlic cloves (California Late) that were peeled and packaged commercially and one test was conducted with controlled atmospheres. In Test 1 (MAP bags of 454g), O2 concentrations averaged 15, 10 and 5% at 0, 5 and 10 degrees , respectively; corresponding CO2 concentrations averaged 8, 15 and 23%. In Test 2 with small vacuum packed bags (30g) inside larger consumer packages (170g), atmospheres in the former averaged 1.5-3% O2 and 20-30% CO2 at all storage temperatures (0, 2.5, 5 and 7.5 degrees C). In both tests, discoloration occurred in areas damaged during peeling, and was associated with lower L* and increased chroma values. In Test 1 excellent visual quality was maintained during 21 and 16 days at 0 and 5 degrees C, respectively, and acceptable quality was maintained for 12 days at 10 degrees C. In Test 2, very good visual quality was maintained up to 28 days at 0 and 2.5 degrees C, and acceptable quality was retained for 21 days at 5 and 7.5 degrees C. Controlled atmospheres (1%O2 alone or with 10%CO2) also showed that high CO2 retarded discoloration and decay at 5 and 10 degrees C. No important changes in texture were observed. Pungency (thiosulfinate and pyruvate concentrations) decreased with time and in relation to storage temperatures. A reasonable expected storage-life of commercially peeled and modified atmosphere packaged garlic is 3-4 weeks at 0 degrees C, 2-3 weeks at 5 degrees C and 1-2 weeks at 10 degrees C.

The use of multivariate analysis as method for obtaining a more reliable shelf-life estimation of fresh-cut produces: A study on pineapple.

Amodio M.L., Derossi A., Mastrandrea L., Colelli G. (Department of Science of Agricultural, Food and Environment, University of Foggia, Italy)

For fresh-cut products the definition of a representative target attribute for shelf-life estimation is very hard to assess because during storage a wide number of chemical, sensorial and physical attributes degrade at the same time. The aim of this study was to obtain a more reliable shelf life estimation of fresh-cut pineapple by applying the Multivariate Accelerating Shelf life Testing (MASLT). This approach is based on Principal Component Analysis (PCA) and allows to estimate the shelf life considering several degradation reactions. Fresh-cut pineapple piece were packaged in PP-PE bags (45 µm, 17.5 x 15.5 cm of size; OTR = 940 cm3m2d-1, ß=3.3) in passive modified atmosphere and stored at 3 different temperatures, 0 5 and 15 degrees C. A total variance of 90.7% was explained by three PC components. The PC scores were used to build a multivariate kinetic chart which resumes the information of the degradation of all the quality attributes studied. The changes of PC1 as a function of time were well described by a first-order kinetic for samples stored at 0 ddegrees C and through a zero-order kinetic for those at 5 and 15 degrees C showing correlation coefficient ranging between 0.88 and 0.95. Results showed as texture, color score and appearance score were the most important variable affecting the PC model. Then, establishing a shelf-life limit for each of the attribute included in the model, a cut-off criterion of – 1.33 was calculated defining a shelf-life of 11, 7.9 and 3.1 days for fresh-cut pineapples stored at 0, 5 and 15 degrees C, respectively.

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