Short Hot Water Research Articles

Quality Maintaining of Stored Cucumbers Under Cold Stress and Shelf Life at Room Conditions by Integrating Calcium Chloride and Short Hot Water

Quality Maintaining of Stored Cucumbers Under Cold Stress and Shelf Life at Room Conditions by Integrating Calcium Chloride and Short Hot Water

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.

Short hot water as safe treatment induces chilling tolerance and antioxidant enzymes, prevents decay and maintains quality of cold-stored cucumbers

This study investigated the effects of treating cucumbers with short hot water dipping at 45 (SHW45) and 55 °C (SHW55) for 5 min compared to fruit dipped in 25 °C water (C). The purpose was to alleviate chilling injury, prevent decay, maintain sensory quality and induce antioxidant enzymes during storage. The cucumbers were held at 4 °C for 7, 14 and 21 d and shelf life at 20 °C for 2 and 4 d. Weight loss, appearance, decay, color, firmness, taste, soluble solids content (SSC), chilling injury (CI), total, reducing and non-reducing sugars, phenolics, electrolyte leakage (EL), peroxidase (POD) and catalase (CAT) activity were measured. The results revealed that SHW55 treatment had the lowest weight loss, CI, EL and POD activity, and had the best appearance, color, taste, and the highest CAT activity during cold storage and shelf life compared with C and SHW45. However, no significant effects were found between C, SHW45 and SHW55 on total, reducing sugars and SSC. No decay appeared on cucumber fruit with SHW55 treatment during the storage period. It may be possible to use SHW55 in a packinghouse as a safe commercial treatment to maintain quality, prevent decay and mitigate chilling injury, prolong storage period and possibility to store cucumber fruit at a non-optimal low temperature.

Hydrothermal pretreatment of wood by mild steam explosion and hot water extraction

The aim of this work was to compare the two most common hydrothermal pre-treatments for wood – mild steam explosion and hot water extraction – both with the prospect of enabling extraction of hemicelluloses and facilitating further processing. Although both involve autohydrolysis of the lignocellulosic tissue, they are performed under different conditions: the most prominent difference is the rapid, disintegrating, discharge employed in the steam explosion opening up the structure. In this comparative study, the emphasis was placed on local composition of the pre-treated wood chips (of industrially relevant size). The results show that short hot water extraction treatments lead to significant variations in the local composition within the wood chips, while steam explosion accomplishes a comparably more even removal of hemicelluloses due to the advective mass transport during the explosion step.

Temperature and Time of Steeping Affect the Antioxidant Properties of White, Green, and Black Tea Infusions.

Tea (Camellia sinensis) is the most highly consumed beverage in the world next to water. The common way of preparation is steeping in hot water which is varying for different type of tea. We investigated the antioxidant properties of 6 type of tea leaves under different time and temperatures of extraction method used. In general, all samples tested in this study demonstrated high levels of antioxidant capacity and antioxidant activity. The results indicate that the antioxidants activity is significantly affected by time and temperature of steeping and the highest was depending on the variety. White state values, green and black teas showed different levels of antioxidants under different extraction conditions. Overall, the highest activity for white tea was in prolonged hot and in some assays prolonged hot and cold extracts, whereas for green tea the highest activity observed in prolonged cold steeping while, for black tea was in short hot water infusion. The results of this study showed the antioxidant capacity of white and green tea was greater than black tea.

Cold quarantine responses of ‘Tarocco’ oranges to short hot water and thiabendazole postharvest dip treatments

This study investigated the effects of brief hot water and thiabendazole (TBZ) postharvest dip treatments on ultrastructural changes of fruit epicuticular wax (ECW), TBZ residues, decay development and quality traits of ‘Tarocco’ oranges [Citrus sinensis (L.) Osbek] subjected to cold quarantine, subsequent simulated transport and shelf-life. Commercially mature fruit were submerged in water at 20°C (control fruit) or TBZ at 1000mg/L and 20°C for 60s, or in hot water without or with TBZ at 300mg/L and 53, 56, or 59°C for 60, 30, and 15s respectively. Following treatments, fruit were stored for 3 weeks at 1°C (simulated quarantine conditions for fruit disinfestations against Mediterranean fruit fly, Medfly), followed by 4 days at 3°C (simulated long distance transport), and finally kept at 20°C for 3 days (shelf-life, SL). Scanning electron microscopy (SEM) analysis of ‘Tarocco’ orange surface showed that the typical wax platelets, lifting around edges of wax plates and areas free of epicuticular wax (ECW), that disappeared after hot water dips at 53–59°C for 60–15s, become visible again after storage for 21 days at 1°C (quarantine conditions), and changes involving the appearance of rough ultrastructure, presence large curled plates, fissured wax crusts, and areas with ECW deficiencies, became much more pronounced after shelf-life. These occurrences were related to the transient effect of hot water treatment in decay control. Conversely, treatments with 300mg/L TBZ 53°C for 60s or 56°C for 30s effectively reduced decay after quarantine. These treatments were as effective as standard treatment with 1000mg/L TBZ at 20°C and produced similar TBZ residue levels in fruit, without impairing fruit quality traits such as visual appearance, weight loss, compression test, sensory attributes, juice color parameters (a*, b*, h, L*, and Chroma), and juice chemical characteristics (soluble solids content, titratable acidity, ascorbic acid, glucose, sucrose, citric acid, total phenols, total anthocyanins, and total antioxidant activity).

短時間温湯処理によるマンゴー炭疽病の防除

短時間温湯処理によるマンゴー炭疽病の防除

Control of Postharvest Diseases of Fruit by Heat and Fungicides: Efficacy, Residue Levels, and Residue Persistence. A Review

Extensive research has been done in recent years to reduce the heavy dependence on chemical fungicides to control postharvest diseases and disorders of horticultural crops. Alternative strategies were based on improved cultural practices, biological control, plant-defense promoters, and physical treatments such as UV illumination, radiofrequency treatment, heat therapy, and storage technologies. Among these, postharvest heat treatments such as hot water dips, short hot water rinsing and brushing, and hot air conditioning have reduced rot development and enhanced fruit resistance to chilling injury in sensitive cultivars while retaining fruit quality during cold storage and shelf life. Additive or synergistic increases in effectiveness were observed by integrating heat therapy with various chemical compounds, thus leading to significant reductions in the application of active ingredients to protect produce from decay. This paper highlights the knowledge on this topic with emphasis on heat therapy effects and factors affecting the uptake, persistence, and performance of fungicide residues when they are applied in combination with hot water.

Effect of yeast antagonist in combination with hot water dips on postharvest Rhizopus rot of strawberries

The potential of using an antagonistic yeast alone or in combination with short hot water dips (at 55 °C for 30 s) for the control of postharvest Rhizopus rot and natural infections of strawberries, and its effects on postharvest quality of fruit was investigated. Cryptococcus laurentii was effective in controlling Rhizopus rot of strawberries. The concentrations of antagonist had significant effects on biocontrol effectiveness: the higher the concentrations of the antagonist, the lower the disease incidence. Rapid colonization of the yeast in wounds was observed during the first 2 days at 20 °C, and then the populations stabilized for the remaining storage period. On strawberry wounds kept at 4 °C, the increase in population density of C. laurentii was lower than at 20 °C, but continued over 20 days after application of the antagonist until it reached a high level. In the experiment to evaluate the effect of hot water dips and yeast antagonist on decay development in artificially inoculated fruits, hot water dips and antagonist yeast, as stand-alone treatments, were capable of reducing the percentage of infected wounds from 96.7% to 65% and 63.3%, respectively. However, in fruit treated with combination of hot water dips and C. laurentii, the percentage of infected wounds was only 43.3%. Incidence of natural decay on treated fruits were similar to that of inoculated fruit. None of the treatments did impair quality parameters of fruit. Thus, the combination of C. laurentii and short hot water dips could be an alternative to chemicals for the control of postharvest Rhizopus rot on strawberries.

Isolation of four heat shock protein cDNAs from grapefruit peel tissue and characterization of their expression in response to heat and chilling temperature stresses

In order to continuously supply horticultural products for long periods, it is essential to store them after harvest in low temperatures. However, many tropical and subtropical fruits and vegetables, such as citrus, are sensitive to chilling. In previous studies, the authors have shown that a short hot water rinsing treatment (at 62°C for 20 s) increased chilling tolerance in grapefruit. In order to gain more insight into the molecular mechanisms involved in heat‐induced chilling tolerance, PCR cDNA subtraction analysis was performed which isolated four different PCR fragments whose expression was enhanced 24 h after the heat treatment, and that showed high sequence homology with various plant HSP18‐I, HSP18‐II, HSP22 and HSP70 genes. It was found that the short hot water treatment given at 62°C for 20 s, but not at lower temperatures of 20 or 53°C, increased the expression of the various HSP cDNAs in grapefruit peel tissue. However, when the fruits were kept at ambient temperatures, the increases in HSP mRNA levels following the hot water treatment were temporary and lasted only between 6 and 48 h. Similar temporary increases in the HSP mRNA levels were detected following exposure of the fruit to a hot air treatment at 40°C for 2 h. Nevertheless, when the fruits were treated with hot water but afterwards stored at chilling temperatures of 2°C, the mRNA levels of the various HSP18‐I, HSP18‐II, HSP22 and HSP70 cDNAs increased and remained high and stable during the entire 8‐week cold‐storage period, suggesting their possible involvement in heat‐induced chilling‐tolerance responses. The chilling treatment by itself increased the expression of the HSP18‐I cDNA, but had no effect on the mRNA levels of any of the other HSP cDNAs. Exposure of fruit to other stresses, such as wounding, UV irradiation, anaerobic conditions and exposure to ethylene, had no effect on the expression of the various HSPs. Overall, the study explored the correlation between the expression and persistence of various HSP cDNAs in grapefruit peel tissue during cold storage, on the one hand, and the acquisition of chilling tolerance, on the other hand, and the results suggest that HSPs may play a general role in protecting plant cells under both high‐ and low‐temperature stresses.

A heat treatment induced the expression of a Na +/H + antiport gene ( cNHX1) in citrus fruit

In previous studies, we showed that a short hot water treatment (at 62 °C for 20 s) increased chilling tolerance in grapefruit. In order to gain more insight into the molecular mechanisms involved in heat-induced chilling tolerance responses, we performed cDNA differential display analysis and isolated a 600-bp polymerase chain reaction (PCR) fragment whose expression was enhanced 24 h after the heat treatment, and that showed high sequence homology with the 5′ region of various NHX1 vacuolar Na +/H + antiporter genes. The full-length cDNA sequence of cNHX1 (for citrus NHX1) was further isolated by 3′-RACE; it had a total length of 2135 bp with an open reading frame of 1626 bp, and encoded a predicted polypetide of 542 amino acids with a molecular mass of 59.8 kDa. The cNHX1 protein shares 83, 78 and 56% identity with the other recently isolated Arabidopsis thaliana, Atriplex gmelini and Oryza sativa NHX1 proteins, respectively. It has been reported that the Arabidopsis AtNHX1 gene partially complemented a salt-sensitive yeast mutation and that overexpression of this gene significantly increased salt tolerance in transgenic plants. In the current study, we showed that the expression of the cNHX1 gene was temporarily induced by a heat treatment, and that its mRNA levels markedly increase during a 6-week cold storage period at 2 °C in heat-treated fruit but not in control untreated fruit, thus suggesting its possible involvement in heat-induced chilling tolerance responses. The expression of the cNHX1 gene was also markedly induced by salt stress, but not by other stresses, such as exposure to ethylene or UV irradiation.

Control of brown rot and blue mold of peach and nectarine by short hot water brushing and yeast antagonists

Abstract We examined the possible use of a hot water brushing (HWB) treatment to disinfect nectarine and peach fruit. In vitro studies showed Monilinia fructicola to be more sensitive than Penicillium expansum to high temperature. In vivo studies of inoculation of peach and nectarine fruit with M. fructicola followed by HWB at 55 or 60 °C for 20 s gave 70 and 80% decay inhibition, respectively, compared with the control. The inhibition percentage of M. fructicola with HWB were similar, if HWB was applied shortly after inoculation or 24 h later. In contrast, the sensitivity of P. expansum spores inoculated into wounds increased when the fruit were treated with HWB 24 h after the inoculation, compared with treatment just after inoculation. The combination of HWB with the application of yeast antagonists was also investigated. We found that treating fruit with HWB at 60 °C for 20 s and then dipping them into a cell suspension (108 cells per ml) of Candida spp. 24 h after inoculation with P. expansum reduced decay development by 60% compared with the controls. Another yeast antagonist, Candida oleophila was inferior in its ability to control Penicillium expansum and M. fructicola compared with other Candida spp. The combination of HWB and Candida spp. showed no significant additional effect against M. fructicola, compared with HWB alone. HWB alone, at 60 °C for 20 s, reduced brown rot development to very low rates. In storage experiments covering 30 days at 0 °C and 10 days of shelf life, HWB and Candida spp. applied separately were each able to reduce natural decay incidence to commercially acceptable levels (

A short hot water rinsing and brushing reduces chilling injury and enhances resistance against Botrytis cinerea in fresh harvested tomato

The effectiveness of a short prestorage hot water rinsing and brushing (HWRB) on resistance to decay development and chilling injury (CI) was studied on pink tomato fruit that were kept for 15 days at 5 or 12°C plus threedays at 22°C. HWRB-52°C for 15 s, or dipping the fruit at 52°C for 1 min (Hot water dip= HWD), significantly reduced decay development and completely inhibited CI symptoms after storage and marketing simulation. The HWRB-52°C treatment enhanced fruit resistance against artificially inoculated Botrytis cinerea when fruit were inoculated 24 hr after treatment. Resistance was less pronounced when the fruit were inoculated 6 hr after treatment, and disappeared completely in fruit inoculated 48 hr after HWRB treatment. On a commercial scale, treatments with hot water dips may be difficult to accomplish since 60 s is considered a long treatment time. Therefore, the alternative method of a very short (15 s) HWRB-52°C treatment would be desirable for treating fresh-harvested tomatoes. This treatment extends storability well over three weeks at 5°C by minimizing CI and enhancing resistance against pathogens during storage.

Host–pathogen interactions modulated by heat treatment

Prestorage heat treatment appears to be a promising method of postharvest control of decay. Heat treatments against pathogens may be applied to fresh harvested commodities by hot water dips, by vapour heat, by hot dry air or by a very short hot water rinse and brushing. Heat treatments have a direct effect slowing germ tube elongation or of inactivating or outright killing germinating spores, thus reducing the effective inoculum size and minimising rots. Heat treatment can also indirectly affect decay development via physiological responses of the fruit tissue. These responses include inducing antifungal-like substances that inhibit fungal development in the fruit tissue, or enhancing wound healing. Heat treatment can induce PR proteins such as chitinase and β-1,3 glucanase, stabilise membranes, elicit antifungal compounds, or inhibit the synthesis of cell wall hydrolytic enzymes (polygalacturonases), and delay the degradation rate of pre-formed antifungal compounds that are present in unripe fruit. Additionally, curing, as a heat treatment can cause the disappearance of wax platelets normally present in untreated fruit and make the fruit surface relatively homogeneous. Thus, cuticular fractures, microwounds and most stomata are partially or completely filled, and early-germinated spores are encapsulated and inactivated by molten wax. The occlusion of possible gaps for wound pathogens as well as the encapsulation and inactivation of early-germinated spores have been considered as additional factors in fruit protection against decay.

Reduction of postharvest decay in organic citrus fruit by a short hot water brushing treatment

Abstract The marketing of organic citrus fruit has markedly increased during the last few years. However, these fruits are not treated with chemical fungicides and suffer from relatively high rates of decay. In this study, we examined the possible use of a new hot water brushing (HWB) treatment, to disinfect the fruits and reduce decay development during postharvest storage. Preliminary observations have shown that a minimum exposure period of 20 s at 56°C was required to inhibit Penicillium digitatum (Pers.: Fr.) Sacc spore germination in vitro. In vivo studies, carried out by rinsing and brushing the fruit 24 h after artificial inoculation with a P. digitatum spore suspension, indicated that HWB at 56, 59 and 62°C for 20 s, reduced decay development in the infected wounds to only 20, 5 and less than 1%, respectively, of that in untreated control fruits or fruits treated with tap water. The effects of HWB at 56, 59 and 62°C for 20 s on epiphytic microflora, was further confirmed by the reduction of the microbial counts (CFU) on the fruit surface to only 24, 12, and less than 1%, respectively, of those on fruit that had been rinsed and brushed with tap water. Scanning electron microscopy showed that HWB at 56°C for 20 s had smoothed the fruit epicuticular waxes and thus covered and sealed stomata and cracks on the fruit surface, which could have served as potential pathogen invasion sites. Postharvest storage experiments using various organically grown citrus cultivars such as ‘Minneola’ tangerines, ‘Shamouti’ oranges and ‘Star Ruby’ red grapefruit, showed that HWB at 56°C for 20 s reduced decay development by 45–55%. The HWB treatment at 56°C did not cause surface damage, and did not influence fruit weight loss or internal quality parameters.

Control of Postharvest Decay of Papaya1

Abstract Thiabendazole (TBZ) applied in a carnauba wax formulation provided effective control of postharvest diseases of papaya (Carica papaya L.) for up to 14 days at 10°C plus ripening at room temperature. Slightly greater control of disease was observed when TBZ was used immediately after a short hot water spray treatment (54°, 1.5 minute). A more severe hot water dip treatment (48°, 20 minutes) was not significantly more effective than TBZ alone. Sodium o-phenylphenate (SOPP) in wax did not reduce decay when used alone or in combination with TBZ.