1-Methyl cyclopropene extends postharvest life of spinach leaves

Senescence of detached spinach leaves either untreated or treated with 0.1 or 1.0 μL L^?1 1-MCP has been investigated. 1-MCP treated leaves had higher chlorophyll content and photosystem II potential quantum yield (Fv/Fm) and lower solute leakage than untreated leaves after storage in darkness at 23 °C for 6 d, indicating a delay of senescence. Ethylene production was increased in spinach supplemented with 1-MCP after 3 d storage and then declined to the rates of untreated leaves. 1-MCP treated spinach had higher ascorbic acid and glutathione concentrations, and a low oxidised/reduced ratio for both antioxidants. Accumulations of ammonium and protein degradation were reduced by 1-MCP. The results presented here indicate that inhibition of ethylene sensitivity can be successfully used to extend the postharvest life of spinach leaves.     

Low irradiance pulses improve postharvest quality of spinach leaves (Spinacia oleraceae L. cv Bison)

The aim of this work is to extend and improve the postharvest life of mature spinach leaves using clean technologies like the use of short pulses of light at low irradiance. After harvest spinach leaves were immediately sealed in polyethylene bags in the laboratory. These bags were placed in a dark chamber at 23 °C under continuous dark or with the application of light pulses (LP) consisting of 15 min each 2–6 h or 7 min each 2 h for 3 d. The chosen irradiance, 30 μmol m⁻² s⁻¹ PPFD, corresponded to the light compensation point previously measured in spinach plants under greenhouse conditions. After the leaves were treated with LP for 3 d, all the samples were transferred to a chamber at 4 °C under continuous dark for another week. Senescence was triggered in leaves under continuous dark after 3 d of storage and delayed in those receiving LP. In addition ascorbic acid and glutathione contents were kept higher in LP-treated than in untreated spinach. These trends were conserved after storage under continuous dark and refrigeration for another week. When LP was applied in combination with 1-MCP the antioxidant capacity was further improved. These results demonstrate that short LP of low irradiance can be used to extend and to improve postharvest life of mature spinach leaves.     

Application of low intensity light pulses to delay postharvest senescence of Ocimum basilicum leaves

Fresh basil (Ocimum basilicum L.) is a highly perishable leafy green vegetable with a storage life of 4–5 d at room temperature. Exposure of basil leaves to temperatures below 12 °C during storage results in chilling injury; therefore, refrigeration cannot be used to extend postharvest life of basil. Typically, leafy vegetables are stored in darkness or extremely low irradiance. Darkness is known to induce senescence, and the initial phase of senescence is reversible by exposure to light. In this work, we studied the effects of low-intensity white light pulses at room temperature on postharvest senescence of basil leaves. Daily exposure for 2 h to 30–37 μmol m⁻² s⁻¹ of light was effective to delay postharvest senescence of basil leaves. Chlorophyll and protein levels decreased, ammonium accumulated and leaves developed visual symptoms of deterioration (darkening) during storage in darkness. Light pulses reduced the intensity of these senescence symptoms. The photosynthesis light compensation point of basil leaves was 50 μmol m⁻² s⁻¹ i.e., higher than the intensity used in this study, and the effect of treatment with red light was the same as with white light, while far red light was ineffective. Light pulses exerted a local effect on chlorophyll loss, but the effect on protein degradation was systemic (i.e., spreading beyond the illuminated parts of the leaf blade). The results of this study indicate that daily treatment for 2 h with low intensity light (30–37 μmol m⁻² s⁻¹ every day) during storage at 20 °C is an effective treatment to delay postharvest senescence of basil leaves. The delay of postharvest senescence by low intensity light pulses seems to be mediated by phytochromes, and it is systemic for protein, and partially systemic for chlorophyll degradation.     

Can hot water treatments enhance or maintain postharvest quality of spinach leaves?

It has been reported that a short duration hot water treatment, applied as a heat shock, improves subsequent postharvest quality in bagged spinach and rocket leaves. This study has established that the maximum hot water temperature and duration before spinach leaves showed damage, was 45 °C for 60 s. Subsequent detailed studies compared postharvest quality of leaves treated at 45 °C for 60 s immediately after harvest with untreated leaves after 5 and 10 days of storage at 4 °C. Heated leaves were significantly lighter and more yellow suggesting enhanced senescence, but leaf membrane integrity and associated gas composition of the storage atmosphere were not significantly different. Hot water treatment at 45 °C for 60 s applied immediately after harvest had a mixed effect on the biochemical constituents of the leaves; total carotenoid concentration was maintained compared to untreated leaves but the contents of ascorbic acid, dehydroascorbic acid, chlorophyll a and b were not affected. These observations suggest that in contrast to other reports, hot water treatments have limited commercial potential for postharvest quality improvement of spinach leaves.     

Effect of cutting on ascorbic acid oxidation and recycling in fresh-cut baby spinach (Spinacia oleracea L.) leaves

Fresh-cut spinach during processing undergoes several mechanical procedures such as cutting, which may induce stress responses. These stresses may trigger the accumulation of harmful reactive oxygen species (ROS). Plants respond through a wide range of mechanisms and ascorbic acid (AsA) has an important role. The combined effect of cutting, temperature and storage time on AsA recycling route in spinach fresh-cut leaves was studied. AsA, gene expression and activities of the enzymes involved in the AsA oxidation and recycling were considered. Spinach leaves were cut in six pieces and stored at 4 °C or 20 °C. AsA content and enzymes activities were measured over six days of storage, while gene expression analyses were performed in a time-point experiment within 24 h after cutting. Results showed that AsA decreased after cutting (from 19.41 mg/100 g FW to 15 mg/100 g FW) and generally was higher in samples stored at 4 °C. After six days, AsA was 10 mg/100 g in control and 5 mg/100 g FW in cut leaves. The expression of genes and activities of the enzymes involved in the AsA oxidation and recycling route were, for some enzymes, in accordance with AsA levels. The APX (EC 1.11.1.11) activity after cutting increased up to 290 nmol AsA mg⁻¹ prot min⁻¹ compared to the control with 190 nmol AsA mg⁻¹ prot min⁻¹. AsA reduction is firstly affected by temperature and aggravated by cutting procedures. AsA represents a valuable postharvest quality indicator of freshness in spinach leaves.     

Alternative strategies for nitrogen fertilization of overwinter processing spinach (Spinacia oleracea L.) in Southern Italy

To identify the best practice for nitrogen (N) fertilization of overwinter processing spinach, two field experiments were carried out in the Foggia plain (Southern Italy), one of the most vocated area for leafy vegetables production. The field trials were aimed to define and suggest the proper fertilizer dose, typology and the right time of application. Experiment 1 evaluated four N fertilizer doses (0, 150, 225, 300 kg ha⁻¹) in a two-year field trial. Experiment 2 was aimed to assess the effect of the split distribution of prilled urea fertilizer in comparison with the application of nitrification inhibitor (DMPP) containing urea fertilizer, broadcasted at sowing.Spinach yield, yield quality (nitrate – NO₃⁻ – and carotenoids content), N-use efficiency and risk of soil nitrate (NO₃⁻-N) leaching were evaluated. The processing spinach yielded 37.8 and 3.6 t ha⁻¹ of fresh and dry yield, respectively (average of the two experiments). Fresh and dry yield among the fertilizing treatments were similar. Also the β-carotene and the lutein content of spinach leaves (19.5 and 38.1 mg kg⁻¹, respectively) were not affected by the N fertilizer dose. Conversely, the N dose strongly influenced the NO₃⁻ content of the leafy vegetable tissues (1286 mg kg⁻¹ on average, 58% lower than the limits imposed by the EC regulation). As expected, the different rainfall pattern influenced both the leaf NO₃⁻ content and the risk of soil NO₃⁻-N leaching. The results achieved demonstrated that, in order to get a favorable trade-off, among yield, yield quality, N-use efficiency and environmental impact, the processing spinach growers of the Foggia plain area should be encouraged to apply 225 kg N ha⁻¹ as maximum fertilization rate. Also, the split urea fertilizer application appeared as the more effective strategy for N fertilization of overwinter spinach in comparison with the use of the nitrification inhibitor containing urea fertilizer, being the last strategy not able to adequately match the N crop demand.     

Extension,anatomy and metabolic activity of leaves in minimally processed leek stalks

When leeks are processed as trimmed stalks, the major problem that arises is inner leaf extension. With the aim to study leaf extension in trimmed stalks, leek pseudostems were initially trimmed at 20 cm from their base and sorted into three experiments. In the first experiment, the stalks were further cut at 2, 4, 6, 8, 10, 12, 14, 16 or 18 cm from the base resulting in two complementary parts: the lower part of 0–2, 0–4, 0–6, 0–8, 0–10, 0–12, 0–14, 0–16 or 0–18 cm and the respective upper part of 2–20, 4–20, 6–20, 8–20, 10–20, 12–20, 14–20, 16–20 or 18–20 cm; in the second experiment, the leaves were detached from the stalk base and marked at 2 cm intervals (leaf-parts), and in the third experiment, detached leaves were grouped into inner (1st–4th), intermediate (5th–7th), and outer (8th–10th) leaves and all experimental material was then stored at 8 °C for 10 d. Maximum leaf extension and leaf-part extension were measured at the end of storage in the first and second experiments, respectively, while metabolic activity measured as CO₂ and C₂H₄ production was monitored during storage in the third experiment. Additionally, leaf material was sampled from the base and mid leaf area of an inner and an outer leaf for anatomical evaluation. The results showed that after 10 d storage at 8 °C of leek pseudostems with 10 leaves trimmed at 20 cm from the base, the inner four leaves were metabolically very active and had the highest leaf extension, which was restricted to the basal 0–8 cm leaf-part. This inner leaf-part constitutes the growth zone in trimmed leek stalks, where cell division and subsequent cell elongation occur, while the outer leaf tissues have already fully expanded.     

Temperature abuse timing affects the rate of quality deterioration of commercially packaged ready-to-eat baby spinach. Part I: Sensory analysis and selected quality attributes

Temperature abuse of fresh-cut products occurs routinely during transport and retail store display. However, the stage of product shelf life during temperature abuse and its impact on sensory attributes have not been studied. This study evaluated the effect of temperature abuse occurring immediately after processing and late in shelf life through measurements of sensory attributes, and membrane integrity of commercially packaged ready-to-eat baby spinach. The packaged products were received within 2 days of processing. Samples subject to early temperature abuse were immediately placed at 1, 4, 8, 12, 16 and 20 °C storage upon arrival, and those subject to late temperature abuse were stored at 1 °C for six days, and then transferred to 4, 8, 12, 16 and 20 °C storage. Package headspace gas composition, in-package visual appeal, purchase intent, product color, off-odor, decay, texture, overall quality, and tissue electrolyte leakage were evaluated every 1–2 day up to 16 day total. Results indicate that when the product temperature is maintained at 1–4 °C, the quality of commercially packaged baby spinach can be retained for up to 18 days post-processing. However, storage temperature of 8 °C or above, significantly (P < 0.001) shortened product shelf life as exhibited by accelerated tissue electrolyte leakage, product yellowing, decay and off-odor development. Most importantly, the product's shelf life stage significantly affected its response to temperature. Quality deterioration proceeded more rapidly when temperature abuse occurred in late as opposed to early shelf life stage.     

Low-intensity light cycles improve the quality of lamb's lettuce (Valerianella olitoria [L.] Pollich) during storage at low temperature

The influence of light on fresh-cut vegetables during storage is controversial, since both positive and negative effects on shelf-life and quality of such products have been observed. In this work, the effect of low-intensity light treatments on lamb's lettuce, a fresh-cut leafy and ready-to-eat vegetable, was investigated during storage at low temperature (6 °C), in comparison with conventional storage (in the dark at 4 °C). Although continuous light treatment (1 cycle of 8 h per day) was deleterious, cycles of light treatments (8 cycles of 1 h per day; 16 cycles of 0.5 h per day) showed positive effects, assessed by evaluating the content of chlorophylls, carotenoids, ATP, glucose and ascorbate. These analyses were performed at the beginning and after 6 days of storage, in comparison with samples stored in the dark at 4 °C. Under low-intensity light treatments, even if performed at a higher temperature (6 °C), the content of such bioactive compounds increased or was at least similar to that found in samples stored in the dark at the same temperature. We suggest that continuous low-intensity light treatments during cold storage of lamb's lettuce are able to promote photosynthesis but, at the same time, induce photo-damage. On the contrary, under intermittent low-intensity light cycles, photosynthesis is only partially activated, while the metabolism of the green tissues is still able to provide carbon moieties for the synthesis of bioactive molecules involved in delaying senescence. Therefore, low-intensity light cycles at 6 °C could contribute to maintain quality of lamb's lettuce, with respect to samples stored in the dark at both 6 and 4 °C. Finally, setting the temperature at 6 °C allows reduction of refrigerator energy consumption during storage.     

Color and textural quality of packaged wild rocket measured by multispectral imaging

Green color and texture are important attributes for the perception of freshness of wild rocket. Packaging of green leafy vegetables can postpone senescence and yellowing, but a drawback is the risk of anaerobic respiration leading to loss of tissue integrity and development of an olive-brown color. The hypothesis underlying this paper is that color and textural quality of packaged wild rocket leaves can be predicted by multispectral imaging for faster evaluation of visual quality of leafy green vegetables in scientific experiments. Multispectral imaging was correlated to sensory evaluation of packaged wild rocket quality. CIELAB values derived from the multispectral images and from a spectrophotometer changed during storage, but the data were insufficient to describe variation in sensory perceived color and texture. CIELAB values from the multispectral images allowed for a more detailed determination of color compared to measurement with a spectrophotometer with an 8 mm aperture. Furthermore, the multispectral images enabled subtraction of background information of the sample and gave more accurate results on visual color of wild rocket leaves. The combination of wavelengths in the NIR range describing textural changes, and wavelengths in the VIS range describing color changes was optimal for quantification of sensory perceived color and textural quality of packaged wild rocket.     

The relationship between chilling injury and membrane damage in lemon basil (Ocimum × citriodourum) leaves

Leaves of lemon basil (Ocimum × citriodourum) were stored in sealed polyethylene bags at 4 °C and 12 °C. At 4 °C, leaf browning, the visible symptom of chilling injury, occurred earlier and was more severe in mature leaves than in young leaves. No positive correlation was found, when comparing young and mature leaves stored at 4 °C, between browning and either substrate levels (free phenolics) or the activities of peroxidase or catechol oxidase, which might catalyse these reactions. The levels of saturated and unsaturated fatty acids differed only slightly and were not correlated with chilling injury. Compared to young leaves, mature ones showed higher lipoxygenase activity throughout the period of low temperature storage. This might indicate more degradation of membrane unsaturated fatty acids. In addition, mature leaves exhibited lower catalase activity than young ones. This suggests lower protection against membrane oxidation in mature leaves. The data thus suggest a correlation between lipoxygenase activity, antioxidant defense, and chilling injury.     

Relationships between the instrumental and sensory characteristics of four peach and nectarine cultivars stored under air and CA atmospheres

‘Big Top’ and ‘Venus’ nectarines and ‘Early Rich’ and ‘Sweet Dream’ peaches were picked at commercial maturity and stored for 20 and 40 d at −0.5 °C and 92% RH under either air or one of the three different controlled atmosphere regimes (2 kPa O₂/5 kPa CO₂, 3 kPa O₂/10 kPa CO₂ and 6 kPa O₂/17 kPa CO₂). Physicochemical parameters and volatile compounds emission were instrumentally measured after cold storage plus 0 or 3 d at 20 °C. Eight sensory attributes were assessed after cold storage plus 3 d at 20 °C by a panel of 9 trained judges, in order to determine the relationship between sensory and instrumental parameters and the influence of storage period and cold storage atmosphere composition on this relationship.A principal component analysis (PCA) was undertaken to characterize the samples according to their sensory attributes. PCA results reflected the main characteristics of the cultivars: ‘Big Top’ was the nectarine cultivar with the highest values for sweetness, juiciness and flavor; ‘Sweet Dream’ was the sweetest peach and was characterized by high values for crispness and firmness, while ‘Venus’ and ‘Early Rich’ were characterized by their sourness. To assess the influence of storage period and CA composition on sensory properties, a PLS model of the flavor of the different samples was constructed using standard quality attributes and volatile concentrations as the X-variables. The model with 2 factors accounted for more than 80% of flavor variance. PLS results indicated that the main influence on flavor perception was storage period. Atmosphere composition also had an influence on flavor perception: flavor perception decreased from samples stored in a 2/5 O₂/CO₂ atmosphere composition to those of 3/10 and 6/17. These results can be qualitatively extended to juiciness and sweetness since all these sensory properties were strongly correlated.     

Effect of cold storage and harvest date on bioactive compounds in curly kale (Brassica oleracea L. var. acephala)

In this study, curly kale stored at 1 °C for 3 and 6 weeks was compared with plants remaining in the field regarding several properties related to human health and sensory quality. Cold storage had no effect on the antioxidant capacity (ORAC assay), total phenols (Folin-Ciocalteu assay) or flavonol content, but reduced the content of vitamin C and soluble sugars. The ratio ascorbic:dehydroascorbic acid decreased from about 3 to 0.5 upon storage. The largest changes in the content of bioactive compounds were found in plants that remained in the field for 6 additional weeks, including many frost days. In these plants, the levels of flavonols, total phenols and antioxidant capacity were reduced by 25–35% and the vitamin C content by more than 50%, whereas soluble sugars and dry matter increased by roughly 20% and 30%, respectively. Among all the curly kale samples, the antioxidant capacity was positively correlated with the level of total phenols (r = 0.73, P < 0.001) and total flavonols (r = 0.70, P < 0.001). Values obtained with a non-destructive method based on chlorophyll fluorescence (ChlF) were well correlated with the flavonol content in the leaves, with the highest correlation found for quercetin (r = 0.76, P < 0.001). Using the ChlF method, the kinetics of the flavonol content during the experiment was recorded. The same method also showed gradients of flavonol content within the plant, with the highest values in the upper leaves and in the tip of the leaves. ChlF measurement, therefore, proved to be a quick and cost-effective alternative to chemical analyses of the flavonol content in curly kale.     

Effects of low temperature storage and sucrose pulsing on the vase life of Lilium cv. Brindisi inflorescences

Lilium cv. Brindisi inflorescences were stored at 2.5 °C for 5, 10, 15 or 20 d, comparing dry storage with storage of the stem ends in water. Prior to storage, inflorescences were treated with 20 or 100 g L⁻¹ sucrose in water, for 20 h at 20 °C. After storage the inflorescences were individually placed in water at 20 °C. The floral buds were still closed at the end of cold storage. In experiments carried out in summer, the time to bud opening was hastened by storage at 2.5 °C in water, more so after a longer period of cold storage. The time to tepal senescence after cold storage in water decreased with the time of storage. The time to tepal abscission was about 1 day longer than the time to tepal senescence. Repeat experiments in late fall and winter additionally showed early leaf yellowing after cold storage. Compared to the experiments in summer, more desiccated floral buds were found in the fall. Pulse treatment with 100 g L⁻¹ sucrose prior to cold storage reduced the number of desiccated buds. However, leaf yellowing was aggravated by the 100 g L⁻¹ sucrose pulse treatment. Compared to cold storage in water, dry storage at 2.5 °C further hastened the time to bud opening and also further hastened tepal senescence and abscission. Dry storage also produced more buds that desiccated or opened poorly. Sucrose treatment (100 g L⁻¹) alleviated the effects of dry storage on tepal senescence and bud desiccation. The data showed that lily cv. Brindisi inflorescences are prone to chilling injury, but can be stored, depending on the treatment, for 5–10 d, during most of the year.     

Non-destructive quality determination of pecans using soft X-rays

Use of soft X-ray digital imaging for non-destructive quality evaluation of pecans was explored. Unshelled pecans were imaged at various X-ray tube voltages from 15 to 50 kVp and currents from 0.1 to 1 mA. Pecan images with good contrast image were identified. The cavity inside the pecan shell and the nutmeat portion were segmented manually in the pecan radiographs. Percent nutmeat area, mean pixel intensity, and local intensity variation adequately determined nutmeat quality, non-destructively. Pecan nutmeat weight was estimated with an error of less than 10% from images taken at 35 kVp–0.75 mA, 40 kVp–0.5 mA, and 45 kVp–0.5 mA. Defects and insects were clearly differentiated in X-ray images after applying contrast stretching or high-frequency emphasis techniques.     

Variation of total FOS,total IOS,inulin and their related-metabolizing enzymes in burdock roots (Arctium lappa L.) stored under different temperatures

Burdock roots were stored for six weeks at three temperatures, 0, 15 and 20 °C, and activity of sucrose hydrolase (SH), 1-kestose hydrolase (1-KH), inulin hydrolase (InH), sucrose:sucrose 1-fructosyltransferase (1-SST) and fructan:fructan 1-fructoslytransferase (1-FFT) were assessed. Simultaneously, total fructooligosaccharides (FOS), total inulooligosaccharides (IOS) and inulin were also assessed during storage. During storage, SH showed an irregular variation at 15 and 20 °C, and was significantly higher at 0 °C showing a continuous increase during the storage period. 1-KH decreased progressively at 15 and 20 °C, but showed a sharp increase at 0 °C after two weeks and decreased afterwards. InH showed a different although more regular pattern by decreasing progressively at 0, 15 and 20 °C. However, the decrease was more significant at 15 and 20 °C during the first two weeks, while at 0 °C the decrease was significant after four weeks storage. 1-SST and 1-FFT activities decreased progressively in a pseudo-linear regression during storage, and showed similar patterns. At 15 and 20 °C, total FOS increased during the first three weeks then decreased, while at 0 °C FOS increased progressively during storage. Total IOS increased during storage, however, this increase was much higher at 0 °C than that observed at 15 and 20 °C. Inulin content decreased during storage and final content was lower at 20 °C. The inulin to total FOS plus total IOS ratio decreased sharply during the first two weeks of storage, then progressively during the last four weeks, while the ratio of hydrolyzing to synthesizing activities was quite stable at 15 and 20 °C, but showed a peak at 0 °C after two weeks. The results suggest that carbohydrate metabolism in stored burdock depends partly on temperature and other physiological factors.     

Opening of cut Iris x hollandica flowers as affected by temperature,dry storage,and light

Flower opening in Iris (Iris x hollandica) depends on elongation of the pedicel + ovary. This elongation lifts the bud above the point where the sheath leaves no longer mechanically inhibit lateral tepal movement. We here report on the effects on flower opening of storage at various temperatures, of holding the flowers dry rather than in water, and of a 12 h light/dark cycle instead of darkness, in cv. Blue Magic. During 3 d of storage in darkness at 11 °C or 6 °C the flowers placed in water opened. Flowers stored at 3.0 °C did not open during the storage period but did so during subsequent vase life at 20 °C. Flowers stored in water at 0.5 °C remained closed, even during subsequent vase life at 20 °C. None of the flowers that were stored dry for 3 d at 15 °C, 11 °C, 6 °C, 3 °C or 0.5 °C opened during vase life. Compared to flowers placed in continuous darkness, a rhythm of 12 h light and 12 h darkness inhibited opening during a 3 d storage period at 20 °C. It is concluded that cut Iris flowers (a) can be stored in water at 3 °C for more than a week, but cannot be stored for 3 d or more in water at 15 °C, 11 °C, 6 °C or 0.5 °C, and (b) cannot be stored dry for long (under the present conditions 3 d or longer) at any of these temperatures. Iris flowers were found to be chilling-sensitive, although only at temperatures of about 0.5 °C.     

Off-odour development in modified atmosphere packaged baby spinach is an unresolved problem

A major problem associated with minimally processed baby spinach (Spinacia oleracea L.) is strong off-odours when stored under modified atmosphere packaging (MAP) with low O₂ and high CO₂. Although the influence of O₂ and CO₂ levels on the quality and shelf-life of baby spinach has been extensively studied, results have been inconsistent and the benefits and disadvantages are not well understood. In this study, the effects of 3 different MAP conditions with low O₂ with CO₂ (stabilizing near 1% O₂ + 11% CO₂), low O₂ alone (stabilizing near 1% O₂, CO₂ scrubber) and moderate O₂ with CO₂ (stabilizing near 10% O₂ + 9% CO₂) were studied during storage at 7 °C for 12 days. Different parameters related to physiology, tissue structure, microbial population and metabolite production were evaluated. Samples exposed to low O₂ with CO₂ had the lowest quality at the end of storage due to high development of off-odours, while off-odours of spinach in low O₂ alone were intermediate but higher than in moderate O₂ with CO₂. Increasing CO₂ concentration significantly increased tissue damage with ammonia release and decreased protein content. Decreasing O₂ concentration significantly reduced the development of aerobic psychrophilic bacteria and Pseudomonas. Senescence occurred more rapidly in baby spinach held in moderate O₂ with CO₂. Baby spinach quality remained acceptable during 7 days of storage at 7 °C, independent of MAP conditions tested. Appropriate MAP for baby spinach must be associated with maintenance of quality and extension of shelf-life.     

Gamma irradiation increases storability and shelf life of minimally processed ready-to-cook (RTC) ash gourd (Benincasa hispida) cubes

Radiation treatment in a dose range of 0.5–2.5 kGy in combination with low temperature storage (4–15 °C) was attempted for improvement in shelf life of ready-to-cook (RTC) ash gourd (Benincasa hispida). Parameters such as microbial load, color, firmness and sensory attributes were monitored during storage. Optimum processing conditions (2 kGy; 10 °C) resulted in improved shelf life of seven days compared to the non-irradiated controls. Total bacterial count of 1.57 × 10³ CFU/g was recorded at the end of storage period (12 d). Higher total phenolic content and total antioxidant activity was observed in irradiated samples as compared to control. Irradiated samples had total phenolic content of 103.3 ± 5.2 mg kg⁻¹ and total antioxidant activity of 384.2 ± 9.7 mg kg⁻¹ while corresponding values for control samples were 67.8 ± 5.4 and 115.5 ± 7.0 mg kg⁻¹ at the end of storage period. Irradiated samples (2 kGy) showed excellent sensory and visual qualities during entire storage period.