Hot Water Dip Research Articles

Influence of hot water dipping, modified atmosphere packaging, and storage periods on pomegranate fruits storability

Influence of hot water dipping, modified atmosphere packaging, and storage periods on pomegranate fruits storability

Combined effect of hot water dipping and Cistus creticus L. leaf extracts on the storage quality of fresh Valencia oranges

Abstract This research was designed to test the combined efficacy of hot water dipping (HWD) and leaf extracts of Cistus creticus L. subsp. creticus on the storage quality of fresh Valencia oranges. Experiments were laid down according to a completely randomised design with 10 different treatments. Five replications, with five fruits in each replication, were used in the current study, and research was designed to continue for 150 days. Quality characteristics were observed with 30-days interval. The applications of this study were (1) Control [dipping in water at 25°C for 5 min]; (2) HWD at 50°C for 5 min; (3) HWD + Additives (A) [Arabic gum (0.2%), potassium sorbate (0.05%), citric acid (0.05%) and vitamin C (0.05%)] at 50°C for 5 min; (4) Additives alone at 25°C for 5 min; (5) 1.0% C. creticus leaf + HWD + A; (6) 1.0% C. creticus leaf + A; (7) 0.5% C. creticus leaf + HWD + A; (8) 0.5% C. creticus leaf + A; (9) 0.5% C. creticus leaf + HWD and (10) 0.5% C. creticus leaf. According to the results obtained, both the HWD and C. creticus, alone or in combination, were effective in preserving orange weight during storage, preventing pathogenic decay, maintaining visual quality and fruit firmness, delaying the reduction in titratable acidity, increasing ascorbic acid content and reducing respiration rate of the orange fruits. Results also suggested that the combined effect of HWD with C. creticus leaf extracts provided the highest efficacy.

Determination and Improvement of the Postharvest Storability of Little Mallow (Malva Parviflora L.): A Novel Crop for a Sustainable Diet

Little mallow (Malva parviflora L.) has been traditionally used as an alternative food source. To the authors’ knowledge, there is no available published information about the postharvest storability of little mallow. This study was conducted in three steps. It aimed to determine the postharvest storability of little mallow leaves and to improve its storability using different strategies. First, the effects of four different storage conditions on the storability of little mallow leaves were tested to determine the most favorable conditions for further studies: 5 ± 1 °C and 95% relative humidity (RH); 9 ± 1 °C and 95% RH; 13 ± 1 °C and 95% RH; and 24 ± 1 °C and 55% RH as control. Preliminary experiments suggested that the best temperature and RH combination is 9 ± 1 °C and 95% RH. Hence, the effects of hot water dipping (HWD) were tested at three different temperatures (40, 45, and 50 °C) for two different durations (60 and 120 seconds); the results suggested that the 40 °C treatment is the most suitable heat treatment for improving the storability of mallow. The final experiments were conducted with 15 different treatments, including HWD, eco-friendly edible bio-materials, modified atmosphere packaging, and ultraviolet radiation. Results showed that low-density polyethylene (LDPE) (60 × 60 cm; thickness, 50 μ) and polypropylene (PP) (35 × 50 cm; thickness, 35 μ) packaging provide the highest efficacy for preserving overall quality. The edible quality of little mallow can be extended to 15 days with PP and 12 days with LDPE. However, both materials caused an abnormal odor after that time. Further studies involving additional edible coatings are necessary to determine if the storage duration of little mallow leaves could be extended.

Chitosan and hot water treatments reduce postharvest green mould in ‘Murcott’ tangor

AbstractThis study aims to evaluate the efficacy of hot water and chitosan treatments to control green mould caused by Penicillium digitatum in 'Murcott' tangor. P. digitatum conidial germination and mycelial growth were evaluated in assays in vitro to verify whether chitosan (0.5, 1 and 2%) or hot water (45, 50, and 55°C, for 30 s, 1, 2, and 5 min) acts directly on fungus development. In vivo assays consisted of inoculating the fruit with P. digitatum (105 conidia ml−1) 4 hr before the chitosan and hot water treatments. Subsequently, green mould incidence and severity were evaluated in fruits stored at 25°C/80% RH for 4 days. Also, treatments combining chitosan and hot water were investigated for controlling green mould and the effect on postharvest quality of fruit stored at 5°C/90% RH. The results showed that P. digitatum conidia germination and mycelial growth were significantly reduced by the hot water treatments especially at 50°C/5 min and 55°C/2 or 5 min in the first case and 50 and 55°C/5 min in the second. These two treatments, when applied alone, 1 min dipping in 2% chitosan or hot water at 50°C/5 min, significantly reduced green mould development in fruit kept at 25°C/80% RH or refrigerated. However, the hot water dip combined with chitosan did not improve green mould control on ‘Murcott’ tangor at room temperature or under refrigeration. Besides, chitosan and hot water did not impair fruit quality. Thus, chitosan and hot water could be an alternative to synthetic fungicides to control green mould in citrus while also contributing to a decrease in the postharvest losses of ‘Murcott’ tangor.

Hot water dipping stimulated wound healing of potato tubers

This study examines the effects of hot water dipping on wound healing of harvested potato tubers and to explore partial mechanisms. The potato ‘cv. Longshu No. 7′ was used as materials, which were artificially wounded and then dipped into 45 °C hot water for 10 min. The wounded tubers were stored at ambient temperature (20−25 °C, RH 70–80%) in dark for wound healing. The weight loss of wounded tubers and the disease index of wounded tubers inoculated with Fusarium sulphureum were determined. The accumulation of suberin poly phenolic, suberin poly aliphatic and lignin at wound sites were observed. The activity of phenylalanine ammonia lyase, peroxidase activity, the content of H2O2, total phenols, flavonoids and lignin were also measured. We found that hot water dipping effectively reduced the weight loss and the disease index of wounded potato tubers. The weight loss of treated tubers was 45.1% lower than the control on the 14 d of healing, and the disease index of treated tubers was 18.2% lower than the control on the 21 d of healing. Hot water dipping significantly stimulated the accumulation of suberin poly phenolic, suberin poly aliphatic and lignin at wound sites. The thickness of suberin poly phenolic, suberin poly aliphatic and lignin cell layers of treated tubers were 28.9%, 23.2% and 18.9% higher than the control on the 21 d of healing, respectively. Moreover, hot water dipping significantly enhanced the activity of phenylalanine ammonia lyase and peroxidase. Meanwhile, the H2O2 content, total phenols, flavonoids and lignin were also significantly promoted at wound sites by hot water dipping treatment during healing. These results suggested that hot water dipping promotes wound healing of potato tubers by activating phenylpropanoid metabolism, increasing H2O2 content and peroxidase activity, promoting the suberin and lignin accumulation at wound sites and decreasing the weight loss and the disease index of tubers during healing.

Effects of hot water dip or heat conditioning of ‘Star Ruby’ grapefruit quality during quarantine treatment and simulated storage duration

Effects of hot water dip or heat conditioning of ‘Star Ruby’ grapefruit quality during quarantine treatment and simulated storage duration

Improving Storability of “Nanfeng” Mandarins by Treating with Postharvest Hot Water Dipping

The current research aimed at studying the possibility of improving the postharvest storability of “Nanfeng” mandarins by hot water dipping (HWD) treatment. The research was conducted in two phases. Firstly, two different temperatures (50 and 55°C) were tested for three different dipping durations (2, 3, and 4 min) on the mandarin fruits, and the best combination was defined for the prevention of weight loss and fruit decay. Next, the optimal treatment (HWD at 50°C for 3 min) was used in further studies to test the effects on the postharvest fruit quality attributes. Regular measurements were performed to determine total soluble solid (TSS) content, titratable acid (TA) content, vitamin C (VC) content, total sugar content, respiration rate, malondialdehyde (MDA) content, and activities of superoxide dismutase (SOD) enzyme, polyphenoloxidase (PPO) enzyme, and peroxidase (POD) enzyme. According to the results obtained, HWD treatment was found to prevent the loss of TSS, TA, and VC contents during the storage period. The HWD-treated fruits were also found to have a lower respiration rate and MDA content as compared with control treatment. Furthermore, HWD treatment significantly enhanced the activities of SOD, POD, and PPO which are known to enhance tolerance to lipid peroxidation and are associated with the fruit protection from injuries and pathogens. Present results also suggest that the activation of the SOD and POD enzymes is highly related to the respiratory activities of the fresh produce. This suggests that the HWD can be used to improve the storability of “Nanfeng” mandarins by maintaining the postharvest physical and biochemical quality.

Physiological responses of Indian jujube (Ziziphus mauritiana Lam.) fruit after postharvest hot water dipping

Physiological responses of Indian jujube (Ziziphus mauritiana Lam.) fruit after postharvest hot water dipping

Influence of Tap and Hot Water Treatment Before Short-Term Storage on Biologically Active Compounds and Sensory Quality of Wild Rocket Leaves (Diplotaxis tenuifolia L.)

Abstract The aim of this study was to determine the influence of dipping in tap and hot water (53 or 55 °C) before storage and conditions during short-term storage: 4 days at 18–20 °C temperature or 7 days at 0 or 5 °C, on contents of total polyphenols, ascorbic acid, antiradical activity, and sensory quality of leaves of wild rocket (Diplotaxis tenuifolia L.). The highest sensory values, ascorbic acid contents, and antiradical activity were found in fresh leaves. Treatments with tap and hot water before storage reduced ascorbic acid contents and antiradical activity, as well as most sensory parameters regardless of storage conditions. The highest overall quality of wild rocket after storage for 4 days at 18–20 °C was found for leaves not dipped or dipped in tap water. Dipping of the wild rocket in the water at 53 or 55 °C for 3 or 5 s did not improve the overall quality of stored leaves compared with leaves not dipped or dipped in tap water.

Combination of hot water treatment and chitosan coating to control anthracnose in papaya (Carica papaya L.) during the postharvest period

Papaya (Carica papaya L.) suffers deterioration, mainly due to anthracnose caused by Colletotrichum fructicola, during postharvest preservation and export periods. The conventional use of synthetic fungicides, to reduce this disease, has been substituted in recent years by alternative methods that are friendlier to human health and the environment. Studies have demonstrated that a combination of these alternative systems is more effective in controlling pathogen development than the same ones used individually. For this reason, hot water dipping followed by coating with different chitosan concentrations has been studied to decrease or substitute the utilization of fungicides during the papaya postharvest period. Results showed that papayas treated with hot water dipping (49 °C for 20 min) and chitosan coating at 20 g L−1 combination presented a higher reduction in anthracnose than papayas treated only with hot water dipping and fruit treated with prochloraz. In addition, this combined treatment reduced maturity symptoms throughout storage, increased the shelf-life period, and did not have a negative effect on sensory characteristics in contrast to chemical treatments and hot water dips applied individually. These results prompted the combination of hot water dipping and chitosan coating as a valid strategy to reduce papaya anthracnose during the postharvest period.

Effects of hot water dipping on apple heat transfer and post-harvest fruit quality

Post-harvest sanitation of fruit and vegetables is one major concern of the food producing industry. In particular, amount and type of microorganisms (MOs) on fresh commodities determine how long a produce can be stored and sold. Therefore, great efforts are put into the development of effective decontamination methods, which reduce the consumers' health risk and extend shelf life of the produce. One relevant method is hot water dipping. Sanitizing fruits with hot water treatment (HWT) has to manage the conflicting priorities of efficient deactivation of MOs and avoiding compromising fruit quality. Comprehensive knowledge of heat transfer properties within the fruit and of tissue physiological responses to heat treatment are prerequisites for an effective optimization of sanitation conditions. Therefore, objectives of this study were to determine the optimal temperature for a limited heating of the fruit surface and to evaluate potential microscopic alterations of the apple peel by heat. Short-term HWTs at 55 °C for 0.5 min exclusively warm the outermost apple layer to 30.1 °C without any microscopic changes of the fruit surface. At apple calyx and stem regions MOs were concentrated 13 - 200-fold compared to the equator area.

Hot Water Dipping and UV Irradiation of Apples to Control Fruit Rots

Hot Water Dipping and UV Irradiation of Apples to Control Fruit Rots

Postharvest hot water dipping and hot water forced convection treatments alleviate chilling injury for zucchini fruit during cold storage

The effects of hot water dipping (HWD) and hot water forced convection (HWFC) treatments on the quality and membrane integrity of zucchini fruit were investigated during cold storage at 4 °C. Zucchini fruit were treated with hot water dipping at 40 °C for 25 min or hot water forced convection at 40 °C at a water flow rate of 2 m/s for 20 min, each of which produced the same heat absorption inside the fruit. Then, all fruit were placed into refrigerated storage at 4 ± 0.5 °C with 85–90 % humidity for 15 d. The results indicated that treatment with HWD or HWFC alleviated chilling injury (CI) in zucchini fruit compared with an untreated group (CK). Nevertheless, the HWFC treatment was more effective in reducing CI, maintaining quality and alleviating membrane injury than was HWD, which decreased the decline in fruit firmness, Total soluble solids (TSS) content and ascorbic acid (AsA) content and reduced relative electrolyte leakage (EL), malondialdehyde (MDA) content and weight loss in zucchini fruit during cold storage. In addition, analysis of heat transfer progress characteristics indicated that the effect of heat treatment on the quality and membrane integrity of zucchini fruit during cold storage was related not only to heat temperature and time but also to heat transfer modes, including forced convection and natural convection. Yielding the same heat absorption inside the zucchini fruit during hot water treatment, the HWFC treatment with a forced convection heat transfer mode could shorten the heating time and provided more advantages in zucchini fruit preservation during cold storage than did the HWD treatment under a natural convection heat transfer mode.

Influence of sprout inhibiting treatments and packaging methods on storage performance of Kufri Chipsona 4 potato

Effect of sprout inhibiting treatments viz., hot water dip treatment (57.5±0.1°C for 20 min), isopropyl N-(3 chlorophenyl) carbamate (CIPC) treatment on Kufri Chipsona 4 variety of potato during storage was investigated. The control and treated potato tubers were packed in net bag packaging (nylon mesh bags), MAP (Modified atmosphere packaging) and vacuum packaging and stored for four months (120 days) at low temperature (12±1°C) conditions. During the study, it was observed that with increasing the storage period of tubers, there was a overall progressive increase in sprouting (49.7%), physiological loss in weight (PLW) (7.2%), decay loss (67.3%) and decrease in firmness (8.8 kg/cm2) of potato tubers at 120th day of storage. The CIPC treatment recorded no sprouting, lowest PLW of 6.1% and decay loss (53.2%) and; higher firmness (10.2 kg/cm2) compared with the other sprouting inhibiting treatments at 120th day of storage. In all packaging methods, the PLW of tubers was significantly lower (2.0%) in vacuum packaging, whereas, the maximum tuber weight loss (16.6%) was observed in net bag packaging while the lowest severity of decay (19.6%) was recorded in net bag packaging followed by MAP (89.8%) and vacuum packaging (92.6%) at 120th day of storage. The sprouting % was signifantly lower (47.4%) in vacuum packaging followed by net bag packaging (49.2%) and highest in MAP (52.5%). Among the interaction effect, the CIPC treated tubers showed no sprouting when packed in any of the used packaging method. The PLW of CIPC treated tubers was lower (1.2%) under vacuum packaging whereas, the lowest decay loss (12.5%) was recorded when CIPC treated tubers were packed in net bag.

Impacts of minimal processing and hot water dipping of ‘Sonata’ strawberries on volatiles emitted during storage

Strawberries flavour attributes are important quality parameters that have a significant impact on consumer acceptability. Minimal processing and postharvest treatments in many cases neglect the importance of flavour attributes or sacrifice them for better appearance and/or longer shelf life. In addition, only few information is available on the impact of postharvest handling on flavour attributes. Thus, the objectives of this paper were to investigate: i) the effects of minimal processing on changes in composition and relative abundance (%) of volatile organic compounds (VOCs) emitted from strawberries; and ii) the effects of hot water treatments (45 °C) at different dipping duration (5 and 10 min) on the shift in VOC composition of ‘Sonata’ strawberries. Based on gas chromatography-mass spectrometry (GC–MS) analysis, the volatile profiles obtained for strawberries were significantly (p ≤ 0.05) influenced by minimal processing. Aldehydes were most abundant in strawberry puree (34.1%) compared to sliced samples (17.5%) and none were detected in the headspace of intact fruit. Esters were most abundant in the sliced samples (62.9%) compared to intact strawberries (51.2%) and fruit puree (≈ 49%) samples. Hot water treatment and dipping durations had significant impact on the synthesis of methyl and ethyl esters and acetaldehyde in comparison to the untreated (control) samples (p ≤ 0.05). At the end of storage, concentrations of methyl acetate (4.9 ± 0.86 mg mL−1), methyl butanoate (6.7 ± 0.05 mg mL−1), ethyl butanoate (0.6 ± 0.37 mg mL−1), and acetaldehyde (3.1 ± 0.99 mg mL−1) were lowest in strawberries dipped in hot water at 45 °C for 10 min. In contrast, hot water treatment with dipping duration of 5 min best maintained and enhanced the synthesis of methyl butanoate and prevented the accumulation of methyl isobutyl ketone. This study showed that minimal processing had a significant impact on the volatile profile of ‘Sonata’ strawberries, and that hot water treatments play a crucial role on the emission of volatile compounds.

Hot water dips elicit disease resistance against anthracnose caused by Colletotrichum musae in organic bananas (Musa acuminata)

Anthracnose of banana is an aggressive disease, difficult to control during export. Moreover, in organic banana the incidence of this pathogen is higher than in traditional crops due to the lack of use of synthetic fungicide during the pre-harvest period. The effectiveness of hot water dips has been studied in order to reduce C. musae growth and to determine their effect on postharvest and shelf-life physicochemical and sensory quality, with the goal to incorporate them into integrated pest management, and to reduce the use of chemicals. Hot water treatment at 40 °C for 20 min elicited a C. musae severity inhibition (49.5%) significantly higher (p < 0.05) than with other hot water dips. Organic bananas dipped at 40 °C for 20 min had lower (p < 0.05) weight, green color, and firmness loss than with other hot water treatments. Global appearance and flavor, were better (p < 0.05) scored in fruit treated with a 40 °C for 20 min than in non-treated fruit during cold storage and shelf-life period. These results suggest that hot water dip may be potentially useful for controlling anthracnose in organic bananas during the postharvest period without negative effect on their physicochemical and sensory quality.

Postharvest Practices for Organically Grown Products

Summary Quality of produce cannot be improved after harvest, only maintained. Postharvest handling depends on the specific conditions of production, season, method of handling, and distance to market. Under organic production, growers harvest and market their produce at or near the peak ripeness more commonly than in many conventional systems. Organic production often includes more specialty varieties whose shelf life and shipping traits are reduced or even inherently poor. Harvesting and handling techniques that minimize injury to the commodity, as well as increased care with field and packinghouse sanitation, (chlorine, ozone, calcium hypochlorite, sodium hypochlorite and chlorine dioxide, acetic acid, peroxyacetic acid, vinegar, ethyl alcohol, hydrogen peroxide, etc.) during postharvest processes are vital components of a postharvest management plan for organic products. Sodium carbonate, sodium bicarbonate, and physical treatments such as heat treatments (as hot water treatment or dips, short hot water rinsing and brushing or hot air) can significantly lower the disease pressure on the harvested commodities. These sanitation practices are very easy to implement in the organic food production chain. They start in the field and continue during harvesting, sorting, packing, and transportation and continue even in the consumer’s home. All those treatments reduce rot development, provide quarantine security, and preserve fruit quality during cold storage and shelf life. In addition, the use chitosan, propolis, methyl jasmonate, essential oils, carnuba wax, biocontrol agents and modified atmosphere packaging can also reduce decay development during prolonged storage. All these treatments can be applied alone or in combination with each other in order to improve decay control after harvest and provide a healthy and safe product to the consumer. The aim of this chapter is to shed more light on the latest information on permitted treatments for organic products and on the possible mode-of-action of these treatments. This chapter summarizes technologies developed over the past five years that explore special physical treatments applied either directly, or in combination with other means to control rot development and insect infestation on fresh produce.

Hot water treatments to control black rot caused byAlternariasp. in yellow pitahaya (Selenicereus megalanthus)

Postharvest fungal infections in yellow pitahaya (Selenicereus megalanthus) cause the majority of losses during export. Synthetic fungicides are the main strategy for disease control, but constraints associated with the use of this kind of products have led to the search for alternative methods to reduce fungal infections. In this research, the efficacy of hot water dips at several temperatures and times for the control of black rot of yellow pitahaya was assessed by measuring lesion diameter on fruit pre-inoculated with Alternaria sp. The results showed that both treatments 50°C for 2 min and the fungicide imazalil (0.4 g L-1) significantly, reduced lesion diameter (62.8 and 71.4% of reduction, respectively) after 21 days of storage at 12°C compared with control fruit (pre-inoculated with Alternaria sp. and non-treated). The hot water treatment had no significant effect on fruit physiological quality, with similar results for color, firmness, titratable acidity and solid soluble content (SSC) were obtained on fruit treated with hot water and fruit treated with chemical fungicide. In conclusion, these results indicated that dips in hot water may provide a non-chemical alternative treatment for postharvest control of black rot caused by Alternaria sp. in yellow pitahaya. It is a residue-free method, respectful with human health and environment.

Influence of hot water treatments on postharvest physicochemical characteristics of Hayward and Jintao kiwifruit slices

The effect of precutting hot water treatments on the quality of minimally processed kiwifruits was studies. Whole fruits were subjected to hot water dipping (HWD) at 45 °C for 25 or 75 min, minimally processed, packed and stored at 0 °C for 8 days. Weight loss, respiration rate, gas composition, texture, color, titratable acidity, pH, soluble solids content, sensory analysis, vitamin C, total polyphenols, antioxidant capacity, and microbial analysis were investigated. An overall beneficial effect of HWD 45 °C/75 min on the postharvest quality was observed. The fruits subjected to this treatment showed lower respiration rate, maintained the initial color and presented a better visual quality compared to the control. Moreover, both in Hayward and Jintao, heat treatments inhibited the microbial growth during storage. The study selected HWD 45 °C/75 min as the optimal combination to retain postharvest quality of fresh-cut kiwifruit for the cold storage period and throughout the supply chain. Practical applications Extending the shelf-life and improving the food safety without chemical treatments will have a positive impact on industry and consumers. The aim of this work was to evaluate the effect of precut hot water treatment on quality characteristics, microbial growth, and visual aspects of fresh-cut kiwifruit slices. In general, hot water treatments significantly controlled weight losses, color parameters, and microbiological quality of minimally processed kiwifruits. The results indicated that postharvest hot water dipping of whole kiwifruits could be used as an emergent, clean, and environmental friendly process to improve the shelf-life.

Mango value chain improvement through postharvest research and development: a developing country case study

Pakistan is one of the major mango-producing and -exporting countries in the world. During 2007-15, significant postharvest research and development (R&D) work was conducted under the Australian-funded ASLP mango supply chain management/value chain improvement projects (two phases). The project started by laying a postharvest foundation R&D infrastructure in 2007. Fruit quality losses in supply chains were documented. Protocols were developed for maturity testing, de-sapping, storage/sea-freighting, and ripening and postharvest disease management of major mango cultivars. Quantity loss (unmarketable fruit) was around 20% while quality loss (affecting price) was 65 and 70% in Sindhri and Samar Bahisht Chaunsa mango, respectively. Sap burn and postharvest diseases were the most important fruit quality issues at retail. Cultivars differed in terms of fruit harvest maturity indicators, postharvest treatment response, controlled atmosphere conditions and temperatures for storage and ripening. Besides physical de-sapping (on racks), lime wash (de-stemming and dipping fruit in 0.5% lime solution for 2-3 min) was also found to be effective, with morning being the best time for fruit picking. Significant relationships of production locality, orchard management, nutrition (Ca, B and K) and pre-cooling were found with postharvest disease incidence. Postharvest hot-water fungicidal dip of Scholar (active ingredient (a.i.) fludioxonil), Amistar (a.i. azoxystrobin) and Sportak (a.i. procholaz) gave significant fruit disease control. An integrated approach of good production practices, right maturity, correct postharvest fungicidal treatments and pre-cooling was an effective strategy for reducing disease incidence and maintaining better shelf-life at retail. On the basis of R&D and interventions, significant improvement was brought to the local mango industry and export. Sindhri mangoes were sea-freighted commercially to the EU and UK with good fruit quality outturn and overall postharvest life of 40-45 days.