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1.
A radio frequency (RF) treatment, with a pulse mode to increase heating uniformity, was examined as a potential quarantine treatment against fifth instars of the codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), in apples, Malus sylvestris L. var. domestica (Borkh.) Mansf., intended for export to Japan. Apples were exposed in water baths to 27.12‐MHz RF energy at 12 kW with a pulse mode of 30 s‐on/30 s‐off for different durations. The temperature uniformity was determined by measurements at 12 sites evenly spaced at two depths in the fruit. The most promising exposure time was 29 min. The efficacy of the treatment with the pulse mode was examined against the codling moth larvae by using exposures between 27 and 30 min and up to 30 min of holding time in bath after treatment. The treatment that killed all larvae with the least amount of energy was the 29‐min exposure with 50‐min holding time. This treatment was appraised for fruit quality in “Delicious” apples. Some injury was observed when treated fruits were removed from 1C storage after 30 days. When these fruits were held at 25C for 1 week, all were too damaged to evaluate for fruit quality. Although pulse mode increased heating uniformity in the fruit, the thermal requirements to control codling moth larvae may exceed the injury threshold of the fruits.  相似文献   

2.
“Loring” and “Elberta” peaches and “Golden Delicious” apples were irradiated with UV (254nm) to doses of 0.84 × 104 to 40 × 104 erg/mm2 then stored. “Loring” were stored 10 days and “Elberta” 20 days at 12°C. “Golden Delicious” were stored 30 days at 20–25°C in a dark room. Fruit were examined and differences in percentage rot and in physical-chemical properties determined. Percentage rot decreased with increasing UV dose. Fruit were firmer, pH and soluble solids lower and acidity higher for UV-treated than for nontreated peaches; pH was lower and acidity and ascorbic acid higher in UV treated than in nontreated apples. Percentage weight loss was less for UV-treated apples. The results indicated that UV treatment not only reduced storage rots but also delayed ripening of peaches and apples.  相似文献   

3.
This study investigated the efficacy of 3 GRAS‐status, plant‐derived antimicrobials (PDAs), trans‐cinnamaldehyde (TC), carvacrol (CR), and β‐resorcylic acid (BR) applied as an antimicrobial wash for killing Escherichia coli O157:H7 on apples. “Red delicious” apples inoculated with a 5 strain mixture of E. coli O157:H7 were subjected to washing in sterile deionized water containing 0% PDA (control), 0.15% TC, 0.35% TC, 0.15% CR, 0.30% CR, 0.5% BR, or 1% BR for 1, 3, and 5 min at 23 °C in the presence and absence of 1% soil, and surviving pathogen populations on apples were enumerated at each specified time. All PDAs were more effective in reducing E. coli O157:H7 compared to the water wash treatment (P < 0.05) and reduced the pathogen by 4‐ to 5‐log CFU/apple in 5 min. Chlorine (1%) was the most effective treatment reducing the pathogen on apples to undetectable levels in 1 min (P < 0.05). Moreover, the antimicrobial effect of CR and BR was not affected by the presence of soil, whereas the efficacy of TC and BR was decreased in the presence of soil. Further, no bacteria were detected in the wash solution containing CR and BR; however, E. coli O157:H7 was recovered in the control wash water and treatment solutions containing TC and chlorine, in the presence of 1% soil (P < 0.05). Results suggest that the aforementioned PDAs, especially CR and BR could be used effectively to kill E. coli O157:H7 on apples when used as a wash treatment. Studies on the sensory and quality characteristics of apples treated with PDAs are needed before recommending their usage.  相似文献   

4.
Inactivation of pectinmethylesterase (PME) and polygalacturonase (PG) is required to minimize quality loss in tomato products. Tomato juice was subjected to thermosonication (TS) (24 kHz), at amplitudes of 25, 50 and 75 μm at 60, 65 and 70 °C or heat only treatments. The TS treatment at 60 °C, 65 °C and 70 °C for 41.8, 11.7 and 4.3 min exposure, respectively reduced PME activity by 90%. The heat only treatment at 60 °C, 65 °C and 70 °C for 90.1, 23.5 and 3.5 min, respectively inactivated PME by 90%. TS treatments with 25–75 μm amplitude had no significant impact on the inactivation efficiency between 60 and 70 °C. After TS the average particle size decreased noticeably (< 30 μm) and viscosity increased 2–4 fold, compared to the heat treated or untreated juice (180 μm). These results suggest that TS at 60 and 65 °C could be useful to obtain tomato juice with a low residual PME activity and high viscosity.Industrial relevanceThe processed tomato industry is constantly in search for potential alternative processes to conventional “cold break” and “hot break” treatments that could inactivate the pectic enzymes of importance. The findings of this study would help the industry to inactivate pectinmethylesterase (PME) enzyme at a lower temperature range and also achieve a higher viscosity due to the mechanical effects of thermosonication. Low temperature treatment would enable the retention of fresh-like properties of tomato juice. Based on the findings of this study, thermosonication could be considered as a potential alternative to conventional “cold break” and “hot break” treatments of tomato juice.  相似文献   

5.
‘Valencia’ oranges [Citrus sinensis (L.) Osbeck] were harvested at optimal maturity and either dipped in hot water at 53 °C for 3 or 6 min or at 48 °C for 12 min or cured at 53 °C for 1 or 6 h or at 48 °C for 12 h. The fruits were not degreened, waxed or treated with any post‐harvest fungicides. All fruit samples were stored at 4 °C for 6 months following the treatments. Both hot water dip and curing treatments reduced chilling injury and decay when compared with the untreated control. The most effective treatments were curing of fruit at 53 °C for 6 h and at 48 °C for 12 h. Weight loss and juice yield were higher in cured fruits than those from other treatments, but the heat treatments had no consistent effects on titratable acid, soluble solids, ascorbic acid and peel colour. It was concluded that a pre‐storage hot water dip and curing at high temperatures might be beneficial in preventing chilling injury and decay of ‘Valencia’ oranges for 6 months of storage at 4 °C.  相似文献   

6.
Wounding during processing triggers physiological reactions that limits shelf life of fresh‐cut apples. Exposure of “Empire” and “Crispin” apples at harvest to the ethylene antagonist, 1‐methylcyclopropene (1‐MCP), on the maintenance of fresh‐cut quality was evaluated in combination with post‐cut dipping of NatureSealTM Efficacy of 1‐MCP on fresh‐cut physiology and quality depended on the storage duration and apple cultivar. Ethylene production of apple slices was inhibited by 1‐MCP but not by NatureSeal. Total volatiles produced by fresh‐cut apples were not affected by NatureSeal but by 1‐MCP when 1‐month stored “Crispin” apples were used. 1‐MCP influenced the quality attributes of fresh‐cut slices prepared from apples stored either 4 months in cold storage or 6 months in controlled atmosphere. Enzymatic browning and softening of the cut‐surface, TSS and total microbial growth were suppressed by 1‐MCP in “Empire” apples. The influence of 1‐MCP on quality attributes in “Crispin” apple slices was marginal.  相似文献   

7.
The effect of hot water pre-treatment of in-shell pecans on physicochemical properties, consumer acceptance and purchase intent of dehulled and roasted kernels was evaluated. In-shell pecans were first subjected to hot water at 70, 80 and 90 °C for 8.6, 6.6 and 4.6 min respectively and kernels were later dry roasted at 160 °C for 10 min. The physicochemical properties of hot water treated and untreated nuts, before and after roasting were determined. Furthermore, consumer acceptance and purchase intent of the roasted kernels were determined. Hot water treatment, alone and subsequent roasting had minimal effect on pecans’ physicochemical properties. Consumers liked (< 0.05) the colour and aroma of treated pecans. No effect (> 0.05) of pre-treatment was observed on the acceptability of other sensory attributes. Safety claim increased treated pecans’ overall liking; however, it decreased purchase intent. Hot water treatment showed promise as a post-harvest microbial intervention strategy without affecting the physicochemical properties and consumer acceptability.  相似文献   

8.
BACKGROUND: The efficacy of hot water treatment in facilitating successful reconditioning of processing potato (Solanum tuberosum L.) cultivar Hermes following 6 months cold storage at 4.5 °C was examined. Tubers were subjected to hot water treatments (HWTs) at 52.5, 55.0, 57.5 and 60.0 °C for 0–60, 0–50, 0–40 and 0–20 min, respectively, and then reconditioned for 20 days at 16 °C before evaluated for sprouting, fresh weight loss, membrane permeability, sugar content and processing quality. RESULTS: The study demonstrates that in order to achieve complete inhibition of sprouting during potato reconditioning HWTs must exceed the thermal tolerance threshold of the tubers. Short‐duration HWT was effective in retarding sprout growth and tuber dehydration without significantly affecting storage parenchyma membrane permeability, tuber sugar content or processing quality. On the contrary, prolonged HWT caused extensive heat damage, loss of membrane integrity and induced an increase in tuber sucrose and reducing sugar content resulting in deterioration of chip colour in proportion to treatment duration. CONCLUSION: Although HWT at 52.5–60 °C following long‐term cold storage did not improve the processing quality of potato tubers after 20 days of reconditioning, future work is needed to evaluate the effect of short‐duration HWT on the permissible extent of reconditioning and subsequent processing quality. Copyright © 2008 Society of Chemical Industry  相似文献   

9.
The effect of hot water dipping (HWD) at 40, 44 and 48 °C for 6 and 12 min on germination of conidia of brown rot fungus (Monilinia laxa) in vitro and the effect of HWD at 48 °C for 6 and 12 min on the fruit quality and development of M. laxa on peach cv. “Roig” and nectarine cv. “Venus” after artificial inoculation in cold storage were studied. Temperature and duration of treatment significantly affected germination of conidia. After HWD at 48 °C for 12 min, the lowest germination of conidia (9%) was recorded, which was more than 10 times lower than control (93%). After 3 days from inoculation, there were 80% of inoculated spots with visual symptoms of decay caused by M. laxa on control peaches and 40% of such spots on control nectarines. Successful infections were recorded on only 5% of inoculated spots of nectarine and 10% of inoculated spots of peach after HWD at 48 °C for 12 min. HWD at 48 °C for 12 min significantly decreased titratable acidity and increased soluble solids concentration/titratable acidity ratio in nectarines. No visual symptoms of heat damage were found on fruits as a consequence of any of the studied treatments. The results show that it is possible to control postharvest brown rot (M. laxa) on peach using HWD at 48 °C for 12 min and on nectarine using HWD at 48 °C for 6 min without a significant loss of fruit quality.  相似文献   

10.
Since methyl bromide fumigation has an adverse effect on human health and environment, it is urgently needed for developing a non-chemical method to replace chemical fumigation for disinfesting milled rice. The purpose of this research was to study possible applications of radio frequency (RF) energy for disinfesting milled rice without affecting product quality. A pilot-scale, 27.12 MHz, 6 kW RF system was used to study RF heating uniformity and develop a treatment protocol for achieving 100% insect mortality and finally evaluating quality attributes in RF treated milled rice during storage. The results showed that the heating time needed only 4.3 min to heat the 3.9 kg milled rice from 25 °C to 50 °C using RF energy, but 480 min for milled rice to reach 48 °C using hot air at 50 °C. After comparing three selected electrode gaps, an appropriate gap of 11 cm was obtained to achieve the heating rate of 5.8 °C/min for further heating uniformity tests. An RF treatment protocol was finally developed to combine 1.0 kW RF power with a forced hot air heating at 50 °C, movement of the conveyor with the speed of 12.4 m/h, two mixings, and holding at 50 °C hot air for 5 min, followed by forced room air cooling through single-layer (2 cm thick) samples. There were no significant differences in quality parameters (moisture, protein, fat, starch, hardness, and color) between RF treatments and untreated controls during storage (P > 0.05). Therefore, RF treatments may provide a practical, effective and environmentally friendly method for disinfesting milled rice.  相似文献   

11.
Thermal inactivation kinetics of heat resistant strains of Salmonella Enteritidis in shell eggs processed by hot water immersion were determined and the effects of the processing on egg quality were evaluated. Shell eggs were inoculated with a composite of heat resistant Salmonella Enteritidis (SE) strains PT8 C405, 2 (FSIS #OB030832), and 6 (FSIS #OB040159). Eggs were immersed in a circulating hot water bath for various times and temperatures. Come‐up time of the coldest location within the egg was 21 min. SE was reduced by 4.5 log at both hot water immersion treatments of 56.7 C for 60 min and 55.6 °C for 100 min. Decimal reduction times (D‐values) at 54.4, 55.6, and 56.7 °C were 51.8, 14.6, and 9.33 min, respectively. The z‐value was 3.07 °C. Following treatments that resulted in a 4.5 log reduction (56.7 °C/60 min and 55.6 °C/100 min), the surviving population of SE remained static during 4 wk of refrigerated storage. After processing under conditions resulting in 4.5 log reductions, the Haugh unit and albumen height significantly increased (P < 0.01) and yolk index significantly decreased (P < 0.05). The shell dynamic stiffness significantly increased (P < 0.05), while static compression shell strength showed no significant difference (P < 0.05). Vitelline membrane strength significantly increased (P < 0.05); although, no significant difference (P < 0.05) was observed in vitelline membrane elasticity. In summary, the hot water immersion process inactivated heat resistant SE in shell eggs by 4.5 log, but also significantly affected several egg quality characteristics.  相似文献   

12.
Quarantine regulations require domestic cherries exported to Japan be treated to control for codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae). The current procedure, methyl bromide fumigation, uses a restricted chemical, reduces fruit quality, and involves health, safety and environmental concerns. Single and double hot water dips were evaluated using fresh ‘Bing’ and ‘Sweetheart’ sweet cherries from Washington state as a potential replacement. The double dip procedure had a pretreatment bath at 40C for 5 min. For both procedures, submersions in heated water from 48 to 55C for 2–14 min were examined for treatment efficacy against third‐instar codling moth and fruit quality. Although a 100% mortality response was found for each temperature and procedure, the submersion durations significantly damaged fruit and stem parameters for both cultivars. Thus, hot water dips are not feasible for Pacific Northwest cherries at this time.  相似文献   

13.
‘Qiandaowuhe’ persimmon fruits (Diospyros kaki L.) were stored at 20 °C after exposed to 20 °C (control), 44 °C (T 44), 48 °C (T 48) or 52 °C (T 52) hot air for 3 h, respectively. Firmness, weight loss, peel color, total carotenoids content, soluble solids content (SSC), titratable acidity (TA), respiration, and ethylene production and cell wall hydrolysis enzymes activities were monitored to determine the efficacy of hot air treatment in delaying persimmon fruit ripening. Results showed that ‘Qiandaowuhe’ persimmon fruit displayed a typical climacteric pattern of respiration and ethylene production. Peak of CO2 and ethylene production was observed after 4 days. Fruit softening was accompanied by a progressive increase in weight loss, total carotenoids content and decrease in h°. The activities of pectinmethylesterase (PME) and polygalacturonase (PG) sharply increased and reached maximal values after 4 and 6 days, respectively. Hot air treatment significantly delayed the onset of climacteric ethylene production, respiration, PME and PG activities in persimmon fruit. Moreover, it also significantly retarded the increase in carotenoids content and SSC, while decreased the firmness, h°, and TA. The hot air treatment promoted fruit weight loss. The shelf-life of persimmon ripening increased 4 days by T 44, and 6 days by T 48 or T 52. Results suggest that hot air treatments can greatly extend the postharvest life of ‘Qiandaowuhe’ persimmon fruit.  相似文献   

14.
Two different heat treatments were compared as to their efficacy in preventing decay and maintaining post-harvest quality of Golden Delicious (Malus domestica Borkh). The apples were treated with a hot water rinsing and brushing machine (HWRB) for different temperatures, and compared to apples given a dry heat treatment (96 h at 38°C) and untreated apples. HWRB at 55°C for 15 s significantly reduced (at P=0.05) decay development in Penicillium expansum-inoculated fruit after 4 weeks at 20°C, or in naturally infected fruit after prolonged storage of 4 months at 1°C plus 10 days at 20°C. This treatment inhibited ripening processes as measured by relatively low respiration rate and ethylene evolution and a slow colour development, compared with non-heated control, and fruit quality was maintained. Heat damage was observed on fruit rinsed and brushed at 60 or 65°C for 15 s. Although similar results were obtained in decay control and fruit quality of HWRB-55°C treated fruit and dry heated fruit, the commercial application of this short pre-storage heat treatment is more feasible than the dry heat treatment.  相似文献   

15.
The influence of pulsed vacuum (PVOD) and ohmic heating (OH) on the osmotic dehydration (OD) kinetics and structure of apples was evaluated. Apple cubes (1 cm3) were immersed in a 65 ºBrix sucrose solution at 30, 40 and 50 °C for 300 min. The PVOD treatment was conducted at 5 kPa for 5 min, and the OH treatment was conducted at 100 V (electric field of 13 V/cm). The water loss, solid gain, aw, color and firmness were measured, and the microstructure was analyzed using electronic microscopy. The largest water loss was observed with the OD/OH treatment at 50 °C. The greatest amount of solute uptake and smallest firmness loss were obtained with the PVOD/OH treatment at 50 °C. Color differences were associated with the loss of clarity and corresponded to the transparency gain. OH treatments led to changes in the microstructure, cell walls and tissues of the apples due to the electroporation effect, which explained the increase of mass transference.

Industrial relevance

The aim of this research was to determine the response of apple samples to osmotic dehydration using combined treatments of pulsed vacuum and ohmic heating. Two different technologies, vacuum and ohmic heating at mild temperatures, were used to determine and observe the mass transfer kinetics and microstructure of osmodehydrated apples. In several ohmic heating treatments, the time reduction reached 50% as compared to conventional heating. The increases of temperature, vacuum application and electroporation effect promoted the gain of osmotic solution into the tissue pores, thus reaching equilibrium in the sample with less water loss. Among the investigated conditions, the PVOD/OH treatment at mild temperatures was the best minimal processing method to preserve the fresh-like properties of the apples.  相似文献   

16.
The use of methyl bromide (MeBr) did not detract from the firmness or skin color of‘Delicious’, ‘Golden Delicious’ or ‘Granny Smith’ apples. Fruit fumigation with MeBr resulted in a darkening of the objective and subjective internal flesh color of ‘Delicious apples, particularly unwaxed apples treated with 48g MeBr/m3 at 20°C for 2 hr. Internal flesh color of ‘Golden Delicious’ apples was not influenced at 48g MeBr/m3 at 6°C for 2 hr. Fumigation with 32g MeBr/ m3 at 20°C or 56g MeBr/m3 at 6°C for 2 hr did not detract from the firmness or internal color quality of ‘Delicious’, ‘Golden Delicious’ or ‘Granny Smith’ apples after 60 days in storage. MeBr-treated apples displayed greater acidity and less ethylene production than control fruit. Higher MeBr treatment temperature and the use of wax on fruit directly influenced the reaction of apples to MeBr fumigation.  相似文献   

17.

ABSTRACT

Since many years, the mass density of many agricultural products has been used as a quality‐sorting criterion, and automatic machines have been developed for that purpose. According to the literature, apple flesh density seems to be related to flesh stiffness, but this behavior is not common among all cultivars. However, there is a lack of information on the evolution of apple density during storage. This study aims to investigate changes of “Delicious Pilafa” apple density during storage. Fruits have been preserved at 0, 10 and 16C. Experiments have been repeated for three successive storage periods. Linear equations between density and mass loss have been developed for two ranges of storage temperatures, 0–10C and 10–16C. Moreover, an efficient multifactor linear equation that relates density to storage time and mass loss has also been calculated. “Delicious Pilafa” apples are characterized by a high mass loss rate during storage. Thus, the relationships developed in this study could be useful for quality assessment of stored fruits according to their mass loss.

PRACTICAL APPLICATIONS

Mass loss of “Delicious pilafa” apple during storage can be estimated via fruit density and storage time using the developed equations that refers to a variety of storage conditions. Fruit density can be easily measured as well as storage time can be accurately estimated at a certain moment of storage. Such mass loss correlation is important for “Delicious pilafa” apples, characterized from high mass loss rates during storage and thus this prediction procedure could be very useful as an objective quality criterion during storage. Equations that relate mass loss and storage time with fruit density could be also useful for the estimation of fruit's volume. This is particularly important for respiration rate measurements, where fruits volume is required. Using such relations the estimation of volume is feasible only with weighting and without immersing fruits in water that could affect respiration activity and favor spoilage development.
  相似文献   

18.
Effects of prestorage heat treatment on the texture of three apple cultivars: 'Gloster,'Golden Delicious' and 'Jonagold' (Malus domestica Borkh.) were studied before and after heat treatments at different time-temperature combinations. Changes of apple firmness, extractable juice content, background color, soluble solids concentration (SSC) and pH values were determined after 4 months cold storage (2C, 95% RH). Prestorage heat treatment can inhibit 'Golden Delicious' softening during cold storage but less effective for 'Jonagold' apples. Severe internal browning was found for heat treated 'Gloster' apples after cold storage. Heat treatments had no benefit on apple juiciness maintenance. Heat treated apples showed more physiological disorders compared with the nontreated apples after 4 months cold storage. The effect of prestorage heat treatment seems to be cultivar dependent.  相似文献   

19.
The flesh browning that appears during commercialization period is the main postharvest disorder that is limiting the market of “Rojo Brillante” persimmon in the Mediterranean area. Previous studies have suggested that mechanical damage suffered by the fruit during packing line operations is the trigger of this alteration when fruit is previously subjected to the required deastringecy treatment. In the present work, the effect of hot water treatments (HWTs) on flesh browning incidence of Rojo Brillante persimmon has been investigated. For that, fruits submitted to the commercial deastringency treatment were hot water treated at 45 °C for 30 min or 50 °C for 20 min and then subjected to different intensity of mechanical damage in packing line. Fruit bathed at 25 °C for 25 min and fruit hand-packed acted as control treatments. Our results confirmed that mechanical damage during packing is a decisive factor in the incidence of flesh browning, and this alteration is found to increase the damage intensity. HWTs significantly alleviated flesh browning disorder by affecting the antioxidative system enzymes; the activity of catalase and ascorbate peroxidase was increased by HWTs while the activity of peroxidases was reduced. No changes were observed in polyphenol oxidase and phenylalanine ammonia lyase activity. Therefore, the application of HWTs may be a useful postharvest technology to reduce flesh browning of persimmon induced by packing line operations.  相似文献   

20.
Papaya (Carica papaya L.) fruit is very perishable with a maximum postharvest life of 4 weeks. The effect of forced moist (100% RH) or dry (50%) hot air with or without Thiabendazole (TBZ at 1.2 g active ingredient/L) on the chilling injury (CI), fungi development and quality of ‘Maradol’papaya fruit stored at 5C or 20C for up to 42 days was investigated. Moist hot air at 48.5C or 50C for 4 h caused fruit injury. Dry air at 48.5C for 4 h, alone or in combination with TBZ, decreased CI intensity and fungi development, and the best effect was achieved by combining dry heat treatment and TBZ, without causing negative effects on fruit quality and without causing heat injury. Hot air treatment, especially in combination with TBZ, decreased growth of inoculated Colletotrichum gloeosporioides. Trehalose was not detected in papaya, probably due to the presence of trehalase. Hot water treatment, with or without TBZ, did not cause any negative effect on the content of β-carotene and lycopene.  相似文献   

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