Plastic Clamshell Research Articles

TREATMENT OF CULTIVATED HIGHBUSH BLUEBERRIES (VACCINIUM CORYMBOSUM L.) WITH ELECTRON BEAM IRRADIATION: DOSIMETRY AND PRODUCT QUALITY

ABSTRACT We determined the dose distribution within a tray of highbush blueberries (Vaccinium corymbosum L.) exposed to electron beam irradiation at medium levels (1.0–3.2 kGy) using Monte Carlo and computer tomography scanning technology. We also evaluated the quality of irradiated and nonirradiated (control) fruits stored at 5C and 70% relative humidity during 14 days by a series of chemical analyses. Blueberries packed in plastic clamshell containers (trays) were irradiated using a 10‐MeV linear accelerator with single‐beam fixture (top only). Irradiation of blueberries at 1.1 kGy had no significant (P > 0.05) effect on the fruit quality with the exception of ascorbic acid, which decreased by 17% by the end of storage. Irradiation had an enhancing effect on the total phenolic and tannin content of all the irradiated fruits (10–20% increases). The calculated dose distribution in a pack of blueberries confirmed that the dose is not uniformly distributed within the pack because of density inhomogeneities (flesh, skin air). Dose levels at the bottom of the trays were 18 (±8%) higher than at the top. These results suggest that careful dose distribution examination must be conducted prior to setting up of an irradiation run for the packed fruits. Excellent agreement was found between measured and calculated doses at different electron beam conveyor speeds.PRACTICAL APPLICATIONSLittle information is available on how electron beam irradiation penetrates a complex medium such as packed blueberries. This study presents unique results from a dose distribution calculation method using Monte Carlo simulation and computed tomography scanning techniques, which can be an effective tool for the development of proper irradiation treatment planning of packed fruits and other fresh produce. The suitability of using electron beam technology to preserve the quality characteristics and shelf life of packed blueberries was verified.

Suspended Tray Package for Protecting Soft Fruit from Mechanical Damage

A new suspended fruit packaging system for damage-free transport of soft fruit was developed and laboratory tested. Transit vibration tests simulating a continental U.S. cross-country trip of approximately 4,500 km showed that this suspended fruit system prevents nearly all transport vibration damage to pears when used with a plastic clamshell package and to avocados when used with a plastic clamshell or corrugated fiberboard master container. Comparative damage data are reported for simulated shipment (using American Standards Testing Materials D4169-94 assurance level I) of Hass avocados and Bartlett pears ripened to varying firmness levels.

Consumer Interest in Fresh, In-shell Edamame and Acceptance of Edamame-based Patties

Two studies were conducted to determine consumer interest in fresh, in-shell edamame [Glycine max (L.) Merrill] and acceptance of two edamame-based patties. An in-store consumer research study was conducted in metropolitan Philadelphia to determine consumer demand for and interest in fresh, in-shell edamame. In fall 2004, plastic clamshells of edamame were placed in the produce department of four supermarkets. Consumers who purchased the clamshells were asked to return a survey that was attached to the container. Of the 480 clamshells that were delivered to the four selected supermarkets, 312 (65.0%) were purchased and 33 (10.6%) of the surveys were returned. All respondents indicated that they had heard of or were familiar with edamame before purchasing the container, and 81.2% had previously purchased edamame. Results indicate that 51.6% of respondents were more likely to purchase the edamame because it was grown in Pennsylvania, and 84.4% were more likely to purchase it because it was grown without the use of pesticides. In addition, a friend's recommendation, price, and sample of the product at the supermarket were rated highest among factors likely to affect respondents' purchasing decisions regarding new produce items. Based on the total number of packages sold and conversations with produce department managers, there appears to be a demand for fresh, in-shell edamame among supermarket consumers in metropolitan Philadelphia. A second study involving a consumer sensory evaluation was conducted in Feb. 2005 to determine consumer acceptance of two edamame-based patties. A total of 209 adults were involved, with 106 participants sampling the edamame-based patties on the first day and 103 sampling on the second day. Participants were asked to rate the patty they sampled on overall appeal, appearance, and flavor on a scale of 1 to 9 points (1 point being “dislike extremely” and 9 points being “like extremely”). Overall mean liking for the two patties was 6.38 points and 6.58 points, and mean liking for flavor was 6.44 points and 6.83 points on days 1 and 2 respectively. Based on the sample evaluated, 43.4% and 35.9% of participants, each day, indicated that they “probably would buy” or “definitely would buy” this item from a supermarket. Results suggest that consumers found the two edamame-based patties acceptable, indicating the potential for commercial production. Across the two studies, consumers expressed interest in purchasing fresh, in-shell edamame and edamame-based patties from a supermarket.

Ethanol vapor prior to processing extends fresh-cut mango storage by decreasing spoilage, but does not always delay ripening

This study was undertaken to optimize ethanol vapor application as a ripening inhibitor on whole mangoes to extend fresh-cut mango shelf life. Freshly harvested mangoes were first subjected to hot water (+HW) at 46 °C for 60 or 90 min to simulate quarantine heat treatments, or remained untreated (−HW). Fruit of each batch (+ or −HW) were then held at 20–25 °C for 4 or 7 d (D4 and D7) after the hot water treatment before being exposed to ethanol vapors [0 h (E0), 10 h (E10), or 20 h (E20)]. Fruit were then peeled and cut into slices, packed in plastic clamshells, and stored at 7 °C for 15 d. Only slices from +HW-D4-E20-treated fruit maintained higher firmness, hue angle, and titratable acidity (TA) in storage. The +HW-D7-E10- or E20-treated fruit had higher hue angle than E0, but firmness, total soluble solids, TA, pH, and respiration rate did not differ. Internal ethanol and acetaldehyde were very high in slices from +HW, D4 and D7, E20 and −HW-D7-E20-treated fruit. A sensory panel could perceive higher firmness and acidity in slices from fruit treated with ethanol. However, E20 induced off-flavor, and these fruit were least preferred. Ethanol exposure on fruit was repeated with purchased mangoes that had been subjected to a commercial quarantine heat treatment. A second heat treatment of 18 h at 38 °C and 98% relative humidity was added to one batch of fruit in this experiment. Ethanol vapors did not result in delayed ripening in those mangoes. However, this treatment inhibited microbial growth. The second heat treatment did not improve fresh-cut mango shelf life, and further, microbial growth increased compared to other treatments. It is concluded that, due to inconsistent results, ethanol vapor applied for 20 h to whole mangoes prior to processing for fresh-cut is not a practical approach to delay ripening; however, at lower doses (10 h), it could be used as a safe microbial control in a fresh-cut production sanitation system.

(154) Investigating Consumer Demand for Fresh Market Edamame in Metro-Philadelphia Supermarkets

An in-store marketing study was conducted in Fall 2004 to determine consumer demand for fresh, inshell edamame [Glycinemax (L.) Merrill]. Each Wednesday from 1 Sept. to 6 Oct. 2004, thirty 12-ounce plastic clamshells were placed in the produce department of four supermarkets in metro-Philadelphia, Pa. Packaged edamame remained in the supermarkets for 1 week and was replaced with fresh product when the next weekly delivery was made. A sample recipe, a follow-up survey and an addressed, postage-paid reply envelope were attached to the bottom of each clamshell. The survey was used to determine consumer perceptions, interest in Pennsylvania-grown edamame and the criteria they consider when choosing new produce items sold at supermarkets for themselves and their families. Of the 480 clamshells that were delivered, 312 were purchased. The total number of clamshells purchased weekly ranged from 64 to 87, while the number of clamshells purchased weekly at individual stores ranged from 6 to 30. Thirty-three surveys were returned with all participants responding that they had heard of or were familiar with edamame prior to purchasing the container. Of those who responded, 78.8% had purchased edamame before. Based on the total number of packages sold, a potential demand for fresh, inshell edamame exists among consumers in metro-Philadelphia. Results from this study will be used to assist small-acreage growers interested in marketing specialty vegetable crops, such as edamame, to chain supermarkets. By understanding consumer interests, we are able to more effectively determine which type of packaging and promotional materials best attract the attention of potential buyers.

EVALUATING A SIMPLE SYSTEM FOR BLACKBERRY SHELF LIFE

The postharvest life of blackberries is shortened by decay, leakage, and softness. Shelf life is shortened after periods of rainfall, and often fruit that appear firm in the field soften rapidly in storage. Blackberry selections of interest for advanced selections from plants without fungicide application are routinely screened for shelf life at Lane by storing fruit at 5 °C for seven days. Blackberry varieties are increasingly being used for farmer's markets, national, and international markets. A rapid test to gauge shelf life of blackberry varieties new to growers would be useful in determining the best type of marketing. Ripe blackberries were harvested from Clarksville, Ark., and transported in 260 g plastic clamshells on ice (about 5 °C) to Lane, Okla. Berries were weighed upon arrival and placed at 5 or at 20 °C for 7 and 2 days, respectively. Overall ratings were considerably worse at 20 °C compared to 5 °C, often with decay on all fruit in clamshells held at 20 °C. Separate subsamples of berries, placed individually in egg cartons and held over water at 20 °C (a 99% relative humidity) yielded Rhizopus, Collectotricum, and Botrytis cinerea growth after 24 hours. Because 2 days at 20 °C proved to cause decay in blackberries too quickly, fruit will be held for 1 day at 20 °C in the next season.

RE-COOLING OF STRAWBERRIES AFTER AIR SHIPMENT DELAYS FRUIT SENESCENCE

The objectives of this work were to evaluate the effect of temperature abuse during a simulated air-cargo shipment on the quality of strawberries and to determine the most appropriate cooling method to be used following air-shipment in order to reduce fruit quality loss. Freshly harvested 'Kent' strawberries (Fragaria x ananassa Duch.) were room cooled to 4°C within 4 h immediately after harvest. Fruit were then packed in 0.47-L plastic clamshell containers and stored at 20°C and 60-70% RH for 20 hours to simulate time delays, temperature and humidity typically encountered during air-shipment. After that period, the strawberries were either forced-air re-cooled at 0°C, room re-cooled at 0°C, or held at 20°C to simulate different facility conditions available at the airports. After re-cooling, the fruit were transferred to 0°C and 85-90% RH. Fruit quality was evaluated after harvest, after air-shipment, after re-cooling treatment, and after 6 and 10 d of storage. Temperature abuse resulted in increased weight loss, darkening and toughening of the fruit, and decreased titratable acidity and soluble solids and anthocyanin contents. Results pointed out that re-cooling after temperature abuse was beneficial in maintaining strawberry quality compared to not re-cooling. Forced-air re-cooling to re-cool temperature-abused strawberries while in transit at the airport and/or after air shipment did not provide an advantage over room re-cooling at 0°C.

Life-Cycle Assessment and Environmental Engineering

Life-cycle assessment (LCA) is an analytical framework for measuring environmental and social impacts of a product system or technology across its entire life (ISO 1997), and it supplies a basis for selecting among competing options. This editorial argues that LCA and related tools should be both integral and integrated with practice and scholarship in environmental engineering. Readers not familiar with LCA may consult the references listed below. In brief, LCA encompasses four objective, factbased procedures: In the LCA jargon, the “goal and scope definition” phase defines the aims, product/system, and system boundaries. System boundaries typically range from raw materials extraction and processing, manufacturing, product use, and final disposal. In the “inventory analysis,” air emissions, waterborne effluents, solid wastes, other releases to the environment, energy and materials consumption, and other aspects are quantified for the defined system boundary and related to the product/system function. In “impact assessment,” the inventory’s outputs or burdens are analyzed with respect to environmental relevance, and outcomes are aggregated to a smaller number of relevant environmental categories to address short- and long-term impacts on human health and the environment. Aggregations usually address depletion of abiotic resources, depletion of biotic resources including impacts of land use and loss of biodiversity and life support function, greenhouse effect, stratospheric ozone depletion, ecotoxicity, photo-oxidant formation, acidification, eutrophication, odor, noise, radiation, waste heat, human toxicity, and casualties. In the “interpretation” step, the results are compared with the goal of the study. LCA is also an important tool for “life-cycle design” or “product improvement” where environmental considerations are integrated into product/system development. There are many variants on these themes, and many tools other than LCA with similar aims—e.g., “material flow analysis,” “design for the environment,” “green chemistry,” and “environmentally conscious manufacturing.” There is growing experience with the LCA framework in a wide range of analyses, ranging from everyday items that are well-recognized by the public, e.g., fast-food containers (paper versus plastic clamshell case—or bring-your-own ), to large-scale engineering systems, e.g., transportation and fuels infrastructure. In the environmental engineering field, LCA should have special meaning and consequence as it identifies, quantifies, and assesses the principal environmental burdens—pollutant discharges, environmental impacts, and health risks—that are associated with the system under analysis and that have been the focus of the field for decades. However, LCA studies are (or can be) holistic and much

PREDICTING SHELF LIFE AND QUALITY OF RASPBERRIES UNDER DIFFERENT STORAGE TEMPERATURES

PREDICTING SHELF LIFE AND QUALITY OF RASPBERRIES UNDER DIFFERENT STORAGE TEMPERATURES

Sprayer Type and Pruning Affect the Incidence of Blueberry Fruit Rots

Highbush blueberries (Vaccinium corymbosum L.) in Michigan are treated annually with fungicides to control fruit rots caused by Colletotrichum acutatum J.H. Simmonds, Alternaria sp., and Botrytis cinerea Pers.:Fr. Control with recommended fungicide programs is often inadequate. The goal of this study was to compare the effects of two spray treatments and three levels of pruning severity on fruit rot levels in mature `Jersey' bushes. Two spray treatments were tested for 3 years: 1) recommended fungicide rates applied with a conventional airblast sprayer; 2) 67% of recommended fungicide rates applied with a multifan/nozzle, above-row sprayer. Pruning treatments included light and heavy pruning (compared for 1 year), and light, moderate, and heavy pruning (compared for 3 years). Fruit rot incidence was determined after incubating individual fruit at 100% relative humidity and 21 °C for 7 to 11 days, and after exposing 0.24-L plastic clamshell containers of fruit to simulated commercial handling. The above-row sprayer provided fruit rot control at least equivalent to the airblast sprayer even though less chemical was applied. Anthracnose rot in berries from the top of the bush canopy were reduced by pruning, but those in the bottom of the bush, and levels of other diseases were not consistently affected. Pruning also reduced yields, although the study was too short in duration to determine the long-term impact on production.

539 Firmness of Blueberry Fruit Following Storage in Air or Controlled Atmospheres

Factors affecting the firmness of `Burlington', `Coville', and `Jersey' highbush blueberries (Vaccinium corymbosum L.) during storage in controlled atmospheres or air were characterized. Fruit were stored for up to 9 weeks in 6-ounce plastic clamshells at 0 or 3 °C. Fruit firmness was measured as grams per millimeter of fruit deformation using a FirmTech1 firmness tester (Bioworks, Stillwater, Okla.). Blueberry fruit held in sealed chambers in 0% CO2/15% O2 did not soften during storage. At 0 and 3 °C, fruit firmness of all cultivars increased an average of 30% after 9 weeks of storage. Changes in fruit firmness varied between cultivars and ranged from no change in `Coville' fruit held at 3 °C to an increase in firmness of 9 g·mm–1 per week in `Burlington' fruit held at 3 °C. CO2 inhibited the postharvest firming of blueberry fruit and at higher concentrations induced softening. At 0 °C, fruit firmness decreased below initial values when held in concentrations of CO2 >12% for `Burlington' and >10% for `Coville' and `Jersey'. At 3 °C, fruit were more tolerant to CO2 and softening occurred at CO2 concentration >17% for `Burlington', and >12% for `Coville' and `Jersey' fruit. CO2-induced softening was enhanced by increased storage time. CO2 also was effective in reducing fruit decay. After 9 weeks, 2% and 36% of fruit held in air at 0 and 3 °C, respectively, were decayed. However, all fruit held in 10 to 25% CO2 had <1% decay. Controlled atmospheres of 10% to 15% CO2 reduced decay while maintaining fruit firmness.

Optimizing Flat Design for Forced-air Cooling of Blueberries Packaged in Plastic Clamshells

Forced-air cooling rates of highbush blueberries (Vaccinium corymbosum L.) packaged in 6-oz (177-mL) or 1-pt (473-mL) clamshell containers were affected by positions of vent holes in corrugated flats. Most rapid cooling occurred in flats with vents across the top of the flat. Additional vents aligned in front of clamshells resulted in more rapid and uniform cooling than vents placed between clamshells. Vent holes in the bottom of flats had no effect on cooling rates. Clamshells cooled more slowly in the front of the pallet where cold air entered than in the back of the pallet where cold air exited. Fruit in 6-oz clamshells cooled faster than fruit in 1-pt clamshells.

Fresh-cut Mango Fruit Slices

Preparation and handling procedures for fresh-cut mango slices were developed using `Tommy Atkins', `Haden', and `Palmer' mangoes. Fruit with yellow flesh color (no green color remaining) were optimum maturity for fresh-cut in terms of maintenance of acceptable appearance, texture, and taste; riper fruit developed flesh breakdown and more browning. Postharvest life of fresh-cut mango at 5 °C was 8 to 10 d with no evidence of chilling injury and was limited by flesh browning and loss of firmness. Respiration rates ranged from 32 to 40 mg CO2/kg per hr and ethylene production was typically ≤0.1 μl·kg–1·hr–1. The SSC changed little during storage, while pH varied from 3.5 to 4.8 and TA typically declined by 30% to 40%. Peeling to a depth of at least 2 mm and trimming flesh near the stem scar was necessary to minimize browning. Imported fruit that had been heat-treated for insect quarantine showed more severe browning than Florida fruit that had not been heat-treated. Preparation in aseptic conditions and dipping fruit in a 100 ppm NaOCl solution at pH 7 before and after peeling protected against decay during storage but dipping in chlorine after slicing without removal of excess liquid resulted in flesh translucency and breakdown. Dipping in 1% CaCl2 solution had no effect on flesh firmness (Instron) or browning. Storage in an unvented plastic clamshell container, which developed an atmosphere of 2.25% CO2 plus 19% O2, did not improve shelf life, but a MA of 10% CO2 plus 10% O2 was subjectively judged to slow browning and softening and resulted in no off flavor compared to air storage.