Commercial Cold Storage Research Articles

First Report of Neofusicoccum ribis Causing Postharvest Decay of Apple Fruit from Cold Storage in Pennsylvania.

Neofusicoccum ribis (Slippers, Crous & M.J. Wingf.), previously known as Botryosphaeria ribis (Grossenb. & Duggar), is an aggressive fungal plant pathogen that is part of the N. ribis/N. parvum species complex that causes stem cankers on a variety of woody plant species (2). An isolate of N. ribis was obtained from decayed 'Honeycrisp' apple fruit from a commercial cold storage facility located in Pennsylvania in October of 2011. The decayed apple fruit sample had a brownish lesion that was soft, dry, and leathery on the surface while sporulation was not evident. To conduct Koch's postulates, three 'Golden Delicious' apple fruits were wound-inoculated with a 50-μl mycelial suspension, obtained from aseptically scraping a 7-day-old potato dextrose agar (PDA) culture of the fungus, and was repeated using 'Fuji' apple fruit. The inoculated fruit developed lesions, while water-inoculated fruit were symptomless after 5 days at 20°C. N. ribis was reisolated from infected tissue and was morphologically identical to the original isolate. Genomic DNA was isolated, a portion of the β-tubulin gene was amplified with the gene specific primers, and the amplicon was sequenced and analyzed using BLAST (1). The nucleotide sequence (GenBank Accession No. KC47853) had 99% identity with N. ribis SEGA8 isolate (JN607146.1). The N. ribis isolate produced a grayish-white mycelium with abundant aerial hyphae on PDA and had an olive-colored reverse. Microscopic investigation revealed septate mycelia with right angle branching and conidiomata were not evident on PDA, V8, oatmeal agar (OMA), or water agar (WA). Growth on WA was sparse and transparent, and aerial mycelial growth was not produced. Growth rate analyses were conducted on PDA, V8, and OMA and were 10.1 (±1.39), 20.4 (±1.15), and 17.6 (±0.70) mm/day at 20°C and the experiment was repeated. The minimum inhibitory concentrations (MIC) for the N. ribis isolate was carried out for three postharvest fungicides as described by Pianzzola et al. (3). Briefly, 96 well plates were filled with PDA alone (0 ppm) and PDA amended with 10 fungicide concentrations ranging from 1 to 1,200 ppm for thiabendazole (Mertect), and 1 to 1,000 ppm for fludioxonil (Scholar) and pyrimethanil (Penbotec). A mycelial suspension of the fungus was obtained from pure culture, 50 μl of the mycelial suspension was pipetted into each well, and allowed to grow for 72 h at 25°C. The experiment was conducted twice. The N. ribis isolate displayed MIC values of >1 ppm thiabendazole (Mertect), >1 ppm fludioxonil (Scholar), and 50 ppm pyrimethanil (Penbotec), which are all well below the labeled application rates for these postharvest fungicides. To our knowledge, this is the first report of N. ribis causing postharvest decay on apple fruit obtained from a commercial storage facility in Pennsylvania.

Porous medium modeling and parameter sensitivity analysis of 1-MCP distribution in boxes with apple fruit

1-methylcyclopropene (1-MCP) is a gas used commercially in cold storage rooms to delay ripening of fruit. It is currently not known how the gas distributes in the bins and is taken up by the fruit. Here a porous-medium model is developed based on volume averaging of the transport equations of momentum and 1-MCP in the air and product. The proposed model was compared with experimental data and validated direct-CFD model. The velocity field in and around the stack were well reproduced by the porous medium model. Concentration predictions were in average 4% and maximally 7% over the average measured values. The porous medium model also agrees well with the direct-CFD model. Influential model parameters were identified through parameter sensitivity study. Porosity, skin mass transfer coefficient and specific surface area strongly affect the simulation. Accordingly model simplifications were suggested and recommended for commercial cold storage rooms.

Effects of Short Photoperiod on Codling Moth Diapause and Survival

The potential presence of codling moth, Cydia pomonella L., in apples shipped to countries within the 30th latitudes has raised concerns that this pest could establish and spread in these countries. Previous research demonstrated that codling moth in apples handled under simulated commercial cold storage conditions and held under short day lengths could not break diapause and emerge in sufficient numbers to establish a minimum viable population. This study expands the in-fruit work by examining the ability of codling moth to establish a laboratory population under a short photoperiod of 12:12 (L:D) h, as compared with a long photoperiod of 16:8 (L:D) h. Codling moth larvae were collected from field infested fruits in 2010 and 2011. Moths were collected from the infested fruits and separated into two groups representing the two daylength conditions. In total, 1,004 larvae were monitored for adult emergence and ability to generate a subsequent population. Larvae held under the photoperiod of 12:12 (L:D) h generated only one moth in the 2 yr period, whereas larvae held under the photoperiod of 16:8 (L:D) h generated 186 females and 179 males, that sustained subsequent generations on artificial diet under laboratory conditions. These results indicate that under controlled environmental conditions, codling moth cannot complete diapause and emerge in sufficient numbers to sustain a viable population when held under a short photoperiod.

Fate of Codling Moth (Lepidoptera: Tortricidae) in Harvested Apples Held Under Short Photoperiod

Codling moth, Cydia pomonella L., is a cosmopolitan pest of pome and stone fruits. It has been identified as a quarantine pest of concern in a number of countries where it is not known to occur, most of them tropical or subtropical countries. Although considerable work has been done on the basic biology and physiology of this temperate pest, little is known on its potential to develop and establish in tropical environments with short photoperiods and few to no days below 10 degrees C. Apples were harvested over three field seasons (2007-2009) from unmanaged orchards in central Washington State and subjected to simulated commercial cold storage at 1.1 +/- 2 degrees C for up to 119 d. After cold storage, infested fruits were held at 20 degrees C under a 12:12 L:D photoperiod for up to 6 mo. Over the entire experiment only 27% of the larvae collected exited the fruit and cocooned. Of those 27%, only 1.06% of larvae held under a 12:12 L:D photoperiod successfully emerged as moths. No moths emerged when host fruit would be available in a representative importing country in the tropics over the 3 yr of testing. These results indicate that codling moth in apples from the Pacific Northwest pose little threat of surviving and establishing in tropical regions where daylength is insufficient to break diapause and the chilling requirement is not met.

Maturação e qualidade pós-colheita de ameixas 'laetitia' com a aplicação pré-colheita de AVG e GA3

O objetivo deste trabalho foi avaliar o efeito da aplicação pré-colheita de aminoetoxivinilglicina (AVG; 0; 90; 125 mg L-1) e ácido giberélico (GA3; 0 e 100 mg L-1) sobre a maturação e a qualidade de ameixas 'Laetitia' após o armazenamento refrigerado. Foi utilizado o delineamento em blocos casualizados, com seis tratamentos (três doses de AVG x duas doses de GA3) e quatro repetições. A aplicação do GA3 e do AVG foi realizada 28 e 7 dias antes do início da primeira colheita, respectivamente. O experimento foi conduzido em 2007 e em 2009. Em cada ano foram realizadas três colheitas, sendo 11-01-2007, 17-01-2007 e 25-01-2007 (colheita comercial); 15-01-2009, 22-01-2009 (colheita comercial), e 29-01-2009. Em 2007, frutos da terceira colheita foram armazenados em uma câmara fria comercial durante 22 dias, a 0,5ºC, e umidade relativa de 92% e mais cinco dias de exposição em condição ambiente (temperatura média de 23ºC e umidade relativa média de 60%). A aplicação pré-colheita de AVG (125 mg L-1), isoladamente ou GA3, ou GA3 + AVG, retarda a maturação de ameixas 'Laetitia' na planta. O tratamento pré-colheita de ameixas 'Laetitia' com GA3, seguido da aplicação de AVG, manteve maior firmeza da polpa dos frutos após o armazenamento refrigerado.

Absorção de 1-metilciclopropeno aplicado em maçãs 'Royal Gala' armazenadas em atmosfera refrigerada juntamente com madeira

Este trabalho teve por objetivo avaliar a interferência da madeira utilizada na construção das caixas, denominadas de bins, utilizadas no armazenamento comercial, sobre a eficiência da aplicação de doses de 1-metilciclopropeno (1-MCP) em maçãs da cultivar Royal Gala. Os tratamentos avaliados foram: controle (sem 1-MCP e sem madeira); 1-MCP (625nL L-1); 1-MCP (625nL L-1) + madeira de eucalipto (Eucaliptus sp); 1-MCP (625nL L-1) + madeira de cedrinho (Erisma uncinatum Warm); 1-MCP (1.250nL L 1); 1-MCP (1.250nL L-1) + eucalipto e 1-MCP (1.250nL L-1) + cedrinho. Após quatro meses de armazenamento a 0,5°C mais sete dias a 20°C, não foi observada diminuição da qualidade dos frutos tratados com 1-MCP e armazenados na presença e ausência de madeira, evidenciando que as madeiras de eucalipto e cedrinho não absorvem o 1-MCP a ponto de influenciar a eficiência do produto. A atividade da ACC oxidase, a síntese de etileno, a respiração, a firmeza da polpa e a cor da epiderme não diferiram entre as maçãs tratadas com 1-MCP e armazenadas na presença ou não de madeira. Também não houve diferença entre as doses de 1.250nL L-1 e 625nL L-1 de 1-MCP na maturação dos frutos. Conclui-se que os dois tipos de madeira utilizados na construção das embalagens e que são utilizados para o armazenamento de maçãs em câmaras frigoríficas comerciais não interferiram na eficiência de 1-MCP sobre a maturação dos frutos.

Combination of chitosan and ethanol to control postharvest gray mold of table grapes

Gray mold, caused by Botrytis cinerea, is the most important postharvest disease of table grapes. Chitosan, a natural biopolymer with antifungal and eliciting properties, and ethanol, a common food additive with antifungal properties, are both able to reduce postharvest decay of table grapes. The effectiveness of reduced doses of chitosan and ethanol, applied alone or in combination, to control gray mold of table grapes was evaluated. Artificially inoculated single berries or clusters were immersed in chitosan (0.1 and 0.5%), ethanol (10 and 20%), or their mixture. The combination of 0.5% chitosan with 10 or 20% ethanol improved decay control with respect to their single treatments, while combinations of 0.1% chitosan with 10 or 20% ethanol did not improve gray mold control compared to the treatments applied alone. On single berries stored 7 days at 15 ± 1 °C, the highest levels of decay control were observed on grapes treated with the combination of 0.5% chitosan and 10 or 20% ethanol (reductions of 94 and 97% on cv Autumn Seedless and 69 and 73% on Thompson Seedless, respectively, compared to controls). On small clusters stored 60 days at 0.5 ± 1 °C, the highest percent reduction was observed on grapes treated with the combination of 0.5% chitosan and 10 or 20% ethanol (reductions of 47 and 60% in Thompson Seedless, and 70 and 94% in Autumn Seedless, respectively, compared to controls). The tests with small clusters were carried out to simulate commercial prolonged cold storage of table grapes. The combination of reduced doses of chitosan and ethanol improved the control of gray mold of table grapes compared to their application alone, and the effect was at least additive and at times synergistic.

Effect of different storage conditions on E. coli O157:H7 and the indigenous bacterial microflora on lamb meat

Lamb chops inoculated with 2.23–2.83 log cfu/g of E. coli O157:H7 strain NCTC 12900 were packed in air (AP), vacuum (VP), and two modified atmospheres (MAP) consisting of 100% CO 2 and a commercial mixture of 35% CO 2/35% O 2/30% N 2. All samples (initial total counts < 3.5 log cfu/g) were stored in a commercial cold storage facility set at 4 °C and one AP trial also at 12 ± 1 °C in a temperature controlled incubator. Pathogen and indigenous flora evolution, physicochemical and sensory changes, surface packages temperature and MAP gas composition were monitored throughout the lamb meat shelf life. Temperature monitoring revealed that during chilled storage packed chops exceeded 7 °C about 3% of the time for periods of 10–20 min at 6 h intervals corresponding to defrosting cycles. In AP samples under these conditions, the E. coli O157:H7 strain had an overall increase of 0.48 log cfu/g by day 12. This increase, which may be regarded as an artefact of the sampling procedure, might also be a response to fluctuating temperatures. Regardless of rapid proliferation of the background microflora on AP lamb meat kept at 12 ± 1 °C, the pathogen significantly increased by 2.35 log cfu/g after nine days. There was a slight decrease (0.20 log cfu/g) of the pathogen numbers after four weeks cold storage in VP despite a significant increase in lactic acid bacteria (LAB). With a relatively small outgrowth of LAB, chilled storage in 100% and 35% CO 2 resulted in significant differences compared to similar conditions in air (decrease from initial numbers of 0.80 and 0.45 log cfu/g, respectively). Our data confirm the importance of effective temperature control to prevent pathogen growth on raw meat and also that contaminated meat remains hazardous regardless of refrigeration and protective packaging. Further studies are needed to determine the behaviour of E. coli O157:H7 at temperatures that fluctuate around the minimum for growth.

1-Methylcyclopropene Influences ‘Empire’ and ‘Delicious’ Apple Quality during Long-term Commercial Storage

This study evaluated the effects of 1-methylcyclopropene (1-MCP) on ‘Empire’ and ‘Delicious’ apples (Malus ×domestica) in commercial controlled atmosphere (CA) storage for 12 months and in commercial cold storage for 6 months. Apples were harvested and delivered by growers to a local commercial storage facility. Four different grower lots were chosen for each of three ‘Empire’ and two ‘Delicious’ storage rooms. Fruit were treated with 1-MCP (≈0.8–1.0 ppm) for 24 hours, while control fruit samples were held in a similar nearby storage room. After treatment, control samples were placed with matching 1-MCP-treated samples into either CA (2.5% O2 + 2.5% CO2 at 2.2 °C or 0 °C for ‘Empire’ and ‘Delicious’, respectively) or air storage at 0 to 1 °C. Initial maturity was relatively uniform among the grower lots, with internal ethylene concentration (IEC) averaging less than 1 ppm for ‘Empire’ and 2 to 3 ppm for ‘Delicious’. IEC was lower in apples treated with 1-MCP after air (3 or 6 months) or CA (6, 9, or 12 months) storage, but this effect was reduced after a 14-day ripening period at 22 °C, and was less dramatic in fruit from CA than from air storage. Apples treated with 1-MCP were also firmer than non-treated fruit upon removal from air or CA storage, and this difference became greater with increased poststorage time at 22 °C. 1-MCP-treated apples stored in air had higher soluble solids concentration (SSC), while there was no significant effect of 1-MCP on SSC in fruit held in CA. Core browning developed in ‘Empire’ held in air for 6 months or in CA for 9 or 12 months, and in ‘Delicious’ after 9 or 12 months in CA. 1-MCP decreased the incidence of core browning in ‘Empire’, but increased the incidence in ‘Delicious’. There was no significant effect of 1-MCP on the incidence of internal browning and storage rots, which developed in both cultivars.

MODEL TO PREDICT THE COOL‐DOWN CHARACTERISTICS OF VARIABLE AIR TEMPERATURE POTATO COLD STORAGE USING COMPUTATIONAL FLUID DYNAMICS

ABSTRACT In Indian commercial potato cold storage facilities, the air temperature does not remain constant during the loading period. Also, because of stepwise loading pattern, the product loaded on different days would undergo different time‐temperature histories. Under this transient condition, the product takes longer to reach the steady state and loses more moisture of about 1.7% during 1 month of storage period. In addition, the sensible product‐cooling load is different for the product loaded on different days. In the present study, therefore, the product temperature, moisture loss and sensible product‐cooling load were predicted for the product loaded on different days under the condition of variable storage air temperature in the range of 3.5–10C and constant relative humidity of 90% using the computational fluid dynamics technique. It was found that the product loaded during the middle of loading period incurred more moisture loss than that loaded during early and latter stages of loading. However, the former case imposed more sensible product‐cooling load. The trends of temporal variation of average product temperature, moisture loss and sensible product‐cooling load depended on the day of loading of the product in the cold storage facility.

Quality assessment of differently treated mackerel (&lt;i&gt;Scomber scombrus&lt;/i&gt;)

The quality assessment of differently treated mackerel (Scomber scombrus), sourced from commercial cold storage facilities in Owerri, was carried out using 1kg of fish each of the treatments – T 1 , T 2 , T 3 , and T,sub>4 for the brined, salted, marinade, and control (not treated) respectively. The keeping qualities of the differently treated fishes were evaluated on 2-day intervals using a 5-man test panel that assessed them organoleptically. The brined mackerel recorded acceptable level of freshness up to the 14 th day of observation, while the salted product was acceptable up to the 12 th day. The cold marinade product on the other hand, lost almost all observable characteristics of freshness by the second day. The control however did not last up to the next day, before spoilage manifested. The different preservation techniques were therefore observed to have varying effects on the keeping quality of mackerel ( Scomber scombrus ), with brining and salting being the most preferred. Keywords : mackerel, spoilage, brining, marinade, organoleptic assessment, keeping quality Animal Production Research Advances Vol. 1(2) 2005: 93-96

Lysophosphatidylethanolamine Accelerates Color Development and Promotes Shelf Life of Cranberries

Highly colored cranberries are desired for both fresh and juice markets. Berries accumulate more color when allowed to stay on the vines longer. However, early fall frosts often force growers to harvest before the fruit has reached its optimal color. This is especially true for the berries under the canopy. No product is currently available for grower to accelerate the color development in cranberries. Result from recent studies suggests that a natural lipid, lysophosphatidylethanolamine (LPE), can accelerate color production in fruit and, at the same time, promote shelf life. LPE is a natural lipid and is commercially derived from egg and soy lecithin. The influence of LPE on anthocyanin accumulation and storage quality of cranberry fruit (Vaccinium macrocarpon Ait. `Stevens') was studied. Cranberry plants were sprayed with LPE at about 4 weeks before commercial harvest at multiple locations. Experiments were conducted in 1997, 1998 and 1999. Fruit samples were taken at 2 and 4 weeks after spray application to determine the changes in the fruit color. Plots were wet harvested using a standard commercial method and stored in a commercial cold storage facility. Marketable fruit were evaluated at 1 and 2 months after cold storage to determine effect of LPE on shelf life of cranberries. In general, a preharvest application of LPE resulted in a 9% to 27% increase in fruit anthocyanin concentration compared to the control. LPE treatments also resulted in 8% to 12% increase in marketable fruit compared to the control following cold storage. Influence of LPE on fruit quality was more apparent after 1 month of storage. These results are consistent with the observed effects of LPE on tomatoes. Interestingly ethanol application also enhanced storage quality. Our results suggest that a preharvest application of LPE may have the potential to enhance color and prolong shelf life of cranberry fruit.

First Report of Melting Decay of 'Red Globe' Grapes in California.

Since the late 1990s, a melting decay of 'Red Globe' grapes has occasionally been observed in cold storage facilities in California. Symptoms of the decay included a cracking and dissolution of the epidermis followed by the development of sunken decayed areas. In extreme cases, nearly the entire berry liquefied. The affected berries usually were randomly distributed over the cluster but sometimes berry-to-berry spread seemed to have occurred. The disease has not been observed in the field. Initial symptoms are usually observed after 2 weeks of cold storage (-0.5 to 0°C and 90 to 95% relative humidity). In 2003, melting decay developed in 'Red Globe' grapes in many cold storage facilities in California and in grapes stored for export. Microscopic examination under the skin at the edges of the decayed lesions revealed numerous yeast and bacterial cells. Bacillus subtilis (Ehrenberg) Cohn, Cryptococcus laurentii (Kufferath) Skinner, and Aureobasidium pullulans (de Bary) Arnaud were consistently isolated on potato dextrose agar (PDA) from samples submitted from two cold storage facilities. Certified diagnostic laboratories identified the bacterium and two yeasts. To fulfill Koch's postulates, we performed the following experiments. 'Red Globe' grape berries with the pedicel attached were surface disinfested in a solution of 0.084% sodium hypochlorite, 1.5% ethanol, and 0.005% Tween 20 for 4 min, and washed with sterile deionized water. Grape berries were placed on raised plastic screens in a humid chamber. After the surface of the berries dried, 0.25 ml of a cell suspension (108 cells per ml) of each microorganism was placed on the surface of each berry without wounding. Water (150 to 200 ml) was added to the bottom of the container to create >98% relative humidity (measured with a datalogger), and the containers were incubated at 20°C for 7 days or 0.5°C for 6 weeks. With fruit stored at 20°C, the epidermis of all the berries cracked between 24 and 48 h after inoculation. Severe symptoms of melting decay developed 1 week later. With berries incubated at 0.5°C, melting decay symptoms developed after 6 weeks. Symptoms were most severe on berries inoculated with C. laurentii. However, when inoculated berries were preincubated at 20°C for 14 h prior to storage at 0.5°C, symptoms developed after 3 weeks. In this case, and when berries were incubated at 20°C, symptom expression was similar among the three pathogens. A number (>80%) of the affected berries disintegrated and liquefied in a pattern similar to that observed in berries from commercial cold storage facilities. The pathogen used to inoculate the grapes was consistently isolated in pure culture from subsequent lesions. Therefore, a postharvest disease in 'Red Globe' grapes called melting decay can be caused by the bacterium, B. subtilis, or two different yeast species. To our knowledge, this is the first report of B. subtilis or C. laurentii as pathogens of grape berries in the United States and worldwide. A. pullulans has been isolated from Vitis vinifera (1,2), but is reported for the first time as one of the causal agents of melting decay of 'Red Globe' grapes. All three organisms also caused symptoms on 'Crimson Seedless' grapes, but melting decay has not been reported as a problem in this cultivar.

Use of commercial freezers to control cowpea weevil, Callosobruchus maculatus (Coleoptera: Bruchidae), in organic garbanzo beans.

One California processor of organic garbanzo beans (Cicer arietinum L.), unable to use chemical fumigants, relies on 30-d storage at -18 degrees C to disinfest product of the cowpea weevil, Callosobruchus maculatus (F). To determine whether the storage period may be shortened, the most cold-tolerant life stage of the cowpea weevil was identified. Laboratory studies showed that the egg stage was most tolerant to -18 degrees C and that adults were most susceptible. To examine the efficacy of cold storage disinfestation, bags of black-eyed peas, Vigna unguiculata (L.) Walp., infested with cowpea weevil eggs were buried within garbanzo bean bins placed in a commercial cold storage facility kept at approximately -18 degrees C and removed after 7, 14, and 21 d. Survival was highest in eggs located at the center of the bins and coincided with the slowest cooling rate. Although temperatures within the bins did not reach -18 degrees C until after 14-19 d, egg mortality was estimated to be >98% after just 7 d of exposure. Complete mortality of eggs occurred after 14 d of cold storage. A 2-wk treatment regimen may be sufficient for control of cowpea weevil in organic legumes.

Effect of Gaseous Ozone Exposure on the Development of Green and Blue Molds on Cold Stored Citrus Fruit

The effects of gaseous ozone exposure on in vitro growth of Penicillium digitatum and Penicillium italicum and development of postharvest green and blue molds on artificially inoculated citrus fruit were evaluated. Valencia oranges were continuously exposed to 0.3 ± 0.05 ppm(vol/vol) ozone at 5°C for 4 weeks. Eureka lemons were exposed to an intermittent day-night ozone cycle (0.3 ± 0.01 ppm ozone only at night) in a commercial cold storage room at 4.5°C for 9 weeks. Both oranges and lemons were continuously exposed to 1.0 ± 0.05 ppm ozone at 10°C in an export container for 2 weeks. Exposure to ozone did not reduce final incidence of green or blue mold, although incidence of both diseases was delayed about 1 week and infections developed more slowly under ozone. Sporulation was prevented or reduced by gaseous ozone without noticeable ozone phytotoxicity to the fruit. A synergistic effect between ozone exposure and low temperature was observed for prevention of sporulation. The proliferation of spores of fungicide-resistant strains of these pathogens, which often develop during storage, may be delayed, presumably prolonging the useful life of postharvest fungicides. In vitro radial growth of P. italicum, but not of P. digitatum, during a 5-day incubation period at 20°C was significantly reduced by a previous 0.3 ± 0.05 ppm ozone exposure at 5°C for 4 days. Inoculum density did not influence the effect of gaseous ozone on decay incidence or severity on oranges exposed to 0.3 ± 0.05 ppm ozone at 20°C for 1 week. Susceptibility of oranges to decay was not affected by a previous continuous exposure to 0.3 ± 0.05 ppm ozone at 20°C for 1 week. A corona discharge ozone generator was effective in abating ethylene in an empty export container.

Biological control of blue mould on apple by a strain of Candida sake under several controlled atmosphere conditions

The biocontrol potential of the yeast Candida sake (CPA-1) against Penicillium expansum decay of apples under several controlled atmosphere conditions was investigated. In a laboratory trial under different commercial cold storage conditions, increasing concentrations of C. sake improved decay control. A maximum reduction of decay was achieved at 3% O 2–3% CO 2 atmosphere. It amounted to a 97% lesion reduction after treatment with a suspension containing 2.4×10 6 CFU/ml of C. sake (CPA-1). In a semi-commercial trial at 1°C with wounded fruits, the reduction in decay diameter caused by C. sake exceeded 80% after 60 days at 21% O 2 and 60% after 120 days of storage under controlled atmosphere conditions. For seven controlled atmosphere conditions studied, a significant influence by C. sake on the P. expansum decay was observed, and the lesion size was reduced more than 70% by C. sake at 10 7 CFU/ml. The populations of C. sake (CPA-1) on the apple surface followed the same pattern under all controlled atmosphere conditions studied. They decreased 4–10-fold during the first 2 weeks, followed by an increase to the initial level after 45 days, and thereafter the count remained constant for the period of 90 days examined. This indicated the capacity of C. sake (CPA-1) to colonize the surface of apples under various storage conditions. The ability to colonize was even higher in apple wounds.

INSTRUMENTAL TEXTURE PROFILE ANALYSIS OF PECANS OF VARIOUS OIL AND MOISTURE CONTENTS AFTER FREEZING TREATMENTS

ABSTRACTFreezing of pecans is done to maintain flavor but has a lesser‐known effect on other quality factors such as texture. Pecans were frozen by various methods, thawed and tested for texture by 50% compression of 3‐mm dia. × 5‐mm long cylinders. The Texture Profile Analysis (TPA) parameters, which were, affected most were fracturability, hardness and Area 1. The most extreme, slowest and fastest, freezing rates produced similar TPA values and were different from intermediate freezing rates that simulate commercial cold storage practices. The effect of the various freezing treatments on texture was similar for full‐oil and reduced‐oil pecans and for those sprayed or not sprayed with water.

Nitrogen Applications Alter Tissue and Soil N Levels but Not Postharvest Quality of Boston Lettuce Grown on Ohio Muck Soils

Unreplicated nitrogen rate demonstrations in 1996 indicated that nitrogen fertilizer rates may reduce storage life and postharvest quality of Boston lettuce grown on Linwood muck. A field trial using three planting dates, four nitrogen rates, and six replications was conducted using Boston lettuce cv. Esmirelda. All nitrogen, phosphorus, and potassium was broadcast and disked-in prior to planting. The spring planting used greenhouse-grown plugs. The summer and late summer sowings were direct-seeded. Soil and plant tissue tests were taken and correlated with fertilizer N rate and yield. In the spring planting, each plot was harvested at maturity, rather than all at once. Twenty-four trimmed heads were boxed, hydrocooled, and stored in a commercial cold storage room at 0 to 1 °C. The boxes of lettuce were weighed before and after cooling, and every 24 to 48 h thereafter, until all boxes were deemed not salable. Samples were rated for soft rot symptoms after the final weighing. The spring planting was the only one to show significant differences in days to crop maturity among nitrogen rates. No differences in head weight, weight loss during storage, or number of heads with rot symptoms were found in the mid- or late summer crops. Wrapper leaf nitrate levels at harvest increased with applied nitrogen rate. Residual soil nitrate increased with applied nitrogen in the late summer trial.

Controlled-Atmosphere Cold Storage as a Quarantine Treatment for Nondiapausing Codling Moth (Lepidoptera: Tortricidae) Larvae in Apples

Nondiapausing larvae of Cydia pomonella (L.) in immature apples were held in commercial controlled-atmosphere cold storage at 0 ± 0.28°C, 95-100% RH, and atmospheric components of 1.5-2.0% O2, <1% CO2, with the remainder being mainly N2. Based on adult emergence, survival decreased from 73% at 0 wk to 0% after a 13-wk exposure. A large-scale test of infested apples held in controlled-atmosphere cold storage for 13wk resulted in no adult emergence from an estimated 142,021 immature larvae, including an estimated 40,389 fifth instars, the most tolerant stage. No live larvae or pupae were found when infested apples were sampled after treatment. Because codling moth eggs are also susceptible to low temperatures, controlled-atmosphere cold storage for a minimum of 13 wk is a potential quarantine treatment for codling moth eggs and larvae in apples.

COMMERCIAL ROOM COOLING, HYDROCOOLING, AND FORCED-AIR COOLING OF SNAP BEANS IN WOODEN CRATES AND CORRUGATED CARTONS: EFFECTS ON QUALITY.

Snap beans were room cooled (RC) or forced-air cooled (FA) in a 4.5°C commercial cold storage room, or hydrocooled (HC) in a commercial flume-type unit with 4°C water containing 175 ppm NaOCl. The beans were packed in wirebound wooden crates (WC) or waxed corrugated fiberboard cartons (FC) before (RC, FA) or after (HC) precooking and stored one week at 10°C before evaluation. Ascorbic acid, chlorophyll and fiber contents did not differ among treatments, while moisture content and per cent unshrivelled beans were lowest in FA and highest in HC, and lower in WC than in FC containers. HC reduced development of mechanical damage symptoms (browning) and decay compared to RC and FA. The former effect was attributable to the presence of NaOCl rather than leaching or increased cooling rate in HC. HC beans packed in FC had the highest per cent sound beans and lowest per cent beans showing mechanical damage symptoms of all the treatment combinations tested.