Light exposure during storage preserving soluble sugar and l-ascorbic acid content of minimally processed romaine lettuce (Lactuca sativa L.var. longifolia)

Minimally processed romaine lettuce (MPRL) leaves were stored in light condition (2500 lux) or darkness at 4 °C for 7 d. Light exposure significantly delayed the degradation of chlorophyll and decrease of glucose, reducing sugar, and sucrose content, and thus preserved more total soluble solid (TSS) content at the end of storage in comparison with darkness. While, it did not influenced starch content that progressively decreased over time. The l-ascorbic acid (AA) accumulated in light-stored leaves, but deteriorated in dark-stored leaves during storage. The dehydroascorbic acid (DHA) increased in all leaves stored in both light and dark condition, of which light condition resulted in less DHA than darkness. In addition, the fresh weight loss and dry matter significantly increased and these increases were accelerated by light exposure. Conclusively, light exposure in applied intensity effectively alleviated MPRL quality deterioration by delaying the decreases of pigments, soluble sugar, TSS content and accumulating AA.     

Improving quality of fresh‐cut mango using polysaccharide‐based edible coatings

This study was aimed at evaluating the effect of coatings with alginate (AL), pectin (PE), carboxymethyl cellulose (CMC) or chitosan (CH) on microbial stability, physicochemical attributes, total phenolics and carotenoids content, antioxidant capacity and sensory properties of fresh‐cut mango during 14 days at 4 ± 1 °C. Coated fresh‐cut mango kept microbial counts below 6 logs CFU g^?1, being CH‐coated fresh‐cut mango those that exhibited the lowest microbial counts (1 log CFU g^?1) along entire storage. AL, PE and CMC coatings maintained yellow colour of fresh‐cut mango throughout storage. AL and CH coatings, which have different monomers in their chain, improved the content of antioxidant compounds in fresh‐cut mango as related to uncoated. AL‐coated fresh‐cut mangoes were the toughest, among those coated, during 14 days. The highest consumer acceptance was achieved in AL (90.2%) coated fresh‐cut mango. CH would be the most suitable coating to extend the quality of fresh‐cut mango throughout storage.     

Slicing increases antioxidant capacity of fresh‐cut lotus root (Nelumbo nucifera G.) slices by accumulating total phenols

Slicing is an abiotic stress during fresh‐cut lotus root slices (FLS) preparation. To evaluate the potential ability of slicing to induce antioxidant capacity (AC) in FLS, fresh lotus roots were sliced into 0.4 cm thick slices and stored at 7 °C for 7 days using intact root segments as control. Results showed slicing induced 68.3% higher phenylalanine ammonia‐lyase (PAL) activity and parallel 130.5% more total phenol (TP) accumulation after 7 days storage compared to control. AC values in FLS assayed by FRAP and ABTS^●+ were 41.5% and 93.8% more than those in control samples at the end of storage, respectively. Such increases in AC values were mainly attributed to TP accumulation as a positive correlation existed between AC and TP. However, slicing significantly accelerated FLS browning by increasing the polyphenol oxidase (PPO) activity during storage. Nevertheless, FLS was still marketable with the maximum browning index of 1.9 after 7 days storage.     

Chemical stability of extra-virgin olive oil added with oregano essential oil

Extra virgin olive oil is highly consumed and well known for its nutritional and health benefits. However, it is fatty food highly susceptible to lipid oxidation. The objective of this study was to evaluate the preserving effect of oregano (Origanum vulgare L. spp vulgare called "oregano compacto") essential oil on physical and chemical properties in extra virgin olive oil during storage. Oregano essential oil composition was analyzed by GC-MS. This essential oil was added into extra virgin olive oil at 0.05%. The samples were stored in 3 different conditions: darkness, light exposure, and temperature (60 °C). Chemical indicators of lipid oxidation (peroxide value, p-anisidine value, conjugated dienes, free fatty acidity, and carotenoid and chlorophyll contents) were measured. High content in carvomenthol (22.52%), terpinolene (19.77%), thymol (13.51%), and γ-terpinene (10.30%) were detected in oregano essential oil. Olive oil samples without oregano essential oil stored at 60 °C and exposure at artificial light had the highest peroxide values during storage. Higher p-anisidine and K232 values after day 7 of storage were detected in temperature, darkness, and light exposure treatments. Light treatment was the main factor that degraded chlorophyll causing loss of color. The highest chlorophyll content (3.87 mg/kg) was observed in olive oil with essential oil at the end of storage. In general, olive oil samples added with oregano essential oil had lower peroxide, conjugated dienes, and p-anisidine values and higher chlorophyll and carotenoid contents during storage. Oregano essential oil retards lipid oxidation process in olive oil prolonging its shelf life. PRACTICAL APPLICATION: Oregano essential oil was and is used with the purpose of flavoring and aromatizing food. This essential oil due to its composition has shown antioxidant activity. Synthetic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) are thought to be promoters of carcinogenesis. Extra virgin olive oil is widely consumed because of its nutritional benefits and sensory properties which are very important to be preserved in the product. In this study, the oregano essential oil showed remarkable antioxidant activity in olive oil. Therefore, this essential oil could be considered for the industry as natural antioxidant not only to be used in olive oil but also in other fatty food products to substitute synthetic ones.     

Quality of fresh‐cut purple‐fleshed sweet potatoes after X‐ray irradiation treatment and refrigerated storage

The effect of X‐ray irradiation on the quality of fresh‐cut, refrigerated purple‐fleshed sweet potato (PFSP) cubes was investigated. Packaged sweet potato cubes were treated with 0, 250, 500, 750 or 1000 Gy X‐ray irradiation and stored at 4 ± 1 °C for 14 days. After 14 days, total aerobic bacteria counts were 4.1 and 3.2 log₁₀ CFU g^?1, and mould–yeast counts were 3.3 and 3.0 log₁₀ CFU g^?1 in 750 and 1000 Gy treated samples, respectively. Doses up to 1000 Gy did not affect the firmness, moisture content and anthocyanin content of PFSP cubes throughout storage. PFSP cubes' flesh colour did not change during the first week of storage, but lightness (L*) increased after 14 days. Also, irradiation doses at 750 and 1000 Gy decreased saturation (C*) significantly, producing duller flesh colour than controls. Results indicate that X‐ray irradiation treatment at doses up to 1000 Gy can reduce microbial populations while maintaining the physical quality and anthocyanin content of PFSP cubes up to 14 days of storage.     

Effects of rind removal on physicochemical quality characteristics of fresh‐cut watermelon [Citrullus lanatus (Thunb) Matsum & Nakai] during cold storage

The impact of removing the rind from fresh‐cut watermelon slices was assessed on the quality of the product during storage at 4 °C for 9 days. Flesh lycopene declined from 55.4 to 47.9 mg kg^?1 f.w. and colour lightness (L*) increased from 43.2 to 45.8 after 2 days of storage. Initial heart and placental flesh firmness increased from 7.3 and 9.8 N, respectively, to 9.5 and 12.8 N after 9 days, but were unaffected by rind processing. Electrolyte leakage from placental tissue was unaffected by storage and rind. Rind presence limited juice run‐off by 47.2% and maintained mean total soluble sugar concentration in the slices at 86.0 mg mL^?1 as opposed to 76.8 mg mL^?1 in rind‐less slices. Change in the quality was most pronounced between 0 and 2 day of storage. Removing the rind accelerated senescence and off‐flavour production, while the presence of rind improved the overall storage stability of fresh‐cut watermelon slices.     

Influence of postharvest UV‐C treatment on refrigerated storage of minimally processed broccoli (Brassica oleracea var. Italica)

Minimally processed broccoli was treated with UV‐C light (8 kJ m^?2) and subsequently stored for 21 days at 4 °C. The UV‐C treatment delayed yellowing and chlorophyll degradation during storage. Treated broccoli florets displayed lower electrolyte leakage and respiratory activity, indicating higher tissue integrity. Treated samples showed higher phenolic and ascorbic acid contents as well as higher antioxidant activity than controls. Treated samples also had a higher content of soluble sugars, but no differences in the content of soluble proteins between control and treated samples were detected. The UV‐C treatment also affected bacterial and mould populations. After 21 days at 4 °C the number of colony‐forming units of both populations was lower in treated than in control broccoli florets. The results suggest that UV‐C treatment reduces tissue damage of minimally processed broccoli during storage at 4 °C, thus maintaining nutritional quality and reducing microbial growth. Copyright © 2007 Society of Chemical Industry     

Quality of fresh‐cut tomatoes as affected by salt content in irrigation water and post‐processing ultraviolet‐C treatment

BACKGROUND: There is little information available concerning the effect of sanitizing agents, including ultraviolet (UV‐C) light, on nutritional composition of fresh‐cut produce. In this study, the influence of UV‐C light irradiation (3.2–19.2 kJ m^?2) on the nutritional quality of fresh‐cut tomato cv. Durinta grown under either low (2.4/2.8 dS m^?1) or high (4.9/7.7 dS m^?1) electrical conductivity (EC) of the hydroponic nutrient influx/efflux solution was investigated. RESULTS: When grown under low EC UV‐C light treatment reduced development of microbial population of fresh‐cut tomato, increased phenolic content and delayed degradation of vitamin C after 7 days of storage at 4–6 °C. UV‐C light irradiation had no significant effect on appearance, color or lycopene content of fresh‐cut tomato. In recently harvested intact tomatoes, the lycopene and vitamin C contents were 30% higher in tomatoes irrigated with high EC, whereas the phenolic content was unaffected by the salt treatment. After fresh‐cut processing, phenolic and vitamin C contents of fresh cuts produced from tomatoes treated with high EC decreased by > 10%. This decline was initially accelerated in tomato treated with UV‐C light irradiation. CONCLUSIONS: Our results revealed that fresh‐cut tomatoes are affected dissimilarly by UV‐C treatments, depending on the degree of salt stress undergone by plants before harvest. We determined the impact of a sanitizing procedure on nutritional composition, an effect often overlooked but with great significance to ensure overall quality of fresh produce. Our findings revealed the need for more nutritional studies addressing the effect of multiple stress factors from pre‐harvest to post‐processing stages. Copyright © 2008 Society of Chemical Industry     

Effect of ozone and calcium lactate treatments on browning and texture properties of fresh‐cut lettuce

The effects of three treatments, 1 mg L^?1 ozone at 18–20 °C, 15 g L^?1 calcium lactate (CLac) at 50 °C and a combination thereof, were compared on fresh‐cut lettuce over 10 days of refrigerated storage. Respiration rate, browning and texture were examined as main quality indicators. The use of ozone produced a significantly (P < 0.05) higher oxygen decline than the use of CLac (from day 3 to day 10). At the end of storage, CLac (alone or combined with ozone) samples had higher oxygen content (～9%) than ozone samples (～6%). Enzymatic activity decreased significantly (P < 0.05) in ozone samples. Polyphenol oxidase activity in fresh‐cut lettuce treated with ozone (alone or combined with CLac) showed lower values on day 1 (<2500 units g^?1) and at the end of storage (<3000 units g^?1) than CLac samples (4000–4800 units g^?1). Ozone also reduced peroxidase activity to ～300 units g^?1 after treatment. Finally, pectin methylesterase activity was also reduced with ozone, showing a negative effect on textural properties. Data suggested that CLac maintained quality markers better than treatments with ozone and ozone/CLac combination over 10 days of storage. Copyright © 2006 Society of Chemical Industry     

Consumers' acceptance and quality stability of olive oil flavoured with essential oils of different oregano species

The objective of this study was to evaluate chemical and physical stability and consumers' acceptance of olive oil flavoured with oregano essential oils (EOs; Compacto, Cordobes, Criollo and Mendocino). Samples of olive oil were added with 0.05% EO and stored in dark (D) and light (L) conditions for 126 days. Samples with oregano EO had lower lipid oxidation indicator values [K232, K269, peroxide value (PV) and anisidine value], especially in darkness. Olive oil with Cordobes EO in D had the lowest PV (18.71 meqO₂ kg^?1). Using prediction equations, 20 meqO₂ kg^?1 PV in olive oil should be reached in 34 days in L control sample and in 126 days in the Cordobes EO sample in darkness. Samples with Cordobes and Criollo EOs in darkness had the highest chlorophyll content after 126 days (2.91 and 2.88 mg kg^?1, respectively). Sensory analysis showed that oregano EO addition in olive oil was detected by panellists in discriminative test and affected consumer acceptance.     

The effects of different UV‐B radiation intensities on morphological and biochemical characteristics in Ocimum basilicum L.

BACKGROUND: The effects of short‐term ultraviolet B (UV‐B) irradiation on sweet basil (Ocimum basilicum L. cv. Cinnamon) plants at the 3–4 leaf pair and flowering stages were examined in controlled environment growth chambers. Plants were exposed to 0 (reference), 2 and 4 kJ UV‐B m^?2 day^?1 over 7 days. RESULTS: Exposure of basil plants to supplementary UV‐B light resulted in increased assimilating leaf area, fresh biomass and dry biomass. Stimulation of physiological functions in young basil plants under either applied UV‐B dose resulted in increased total chlorophyll content but no marked variation in carotenoid content. At the flowering stage the chlorophyll and carotenoid contents of basil were affected by supplementary UV‐B radiation, decreasing with enhanced UV‐B exposure. Both total antioxidant activity (2,2‐diphenyl‐1‐picrylhydrazyl free radical assay) and total phenolic compound content were increased by UV‐B light supplementation. Young and mature basil plants differed in their ascorbic acid content, which was dependent on UV‐B dose and plant age. UV‐B radiation resulted in decreased nitrate content in young basil plants (3–4 leaf pair stage). CONCLUSION: These results indicate that the application of short‐exposure UV‐B radiation beneficially influenced both growth parameters and biochemical constituents in young and mature basil plants. © 2012 Society of Chemical Industry     

Effect of frozen storage on thermal stability of sarcoplasmic protein and myofibrillar protein from common carp (Cyprinus carpio) muscle

Thermal stability of sarcoplasmic protein and myofibrillar protein extracted from fresh and frozen common carp was comparatively studied. Total sulphydryl content (SH) in sarcoplasmic protein solution from 5‐month frozen carp decreased by 19.43% compared with fresh sample. The SDS‐PAGE patterns showed that all the bands of sarcoplasmic protein from frozen‐stored samples were almost invisible at 80 °C. Myofibrillar protein from fresh sample exhibited lower turbidity and surface hydrophobicity and higher Ca²⁺‐ATPase activity and SH content than frozen‐stored sample when heated from 20 to 80 °C. The Ca²⁺‐ATPase activity from fresh (M0), 2 (M2)‐ and 5 (M5)‐month frozen‐stored carp was completely lost at 48, 46 and 46 °C, respectively. When heated to 80 °C, the SH content of myofibrillar solutions in M0, M2 and M5 decreased by 26%, 60% and 70%, respectively. Sarcoplasmic and myofibrillar proteins from frozen carp were more susceptible to aggregate during heating treatment.     

Bioactive components,ABTS radical scavenging capacity and physical stability of orange,yellow and purple sweet potato (Ipomoea batatas) powder processed by convection‐ or vacuum‐drying methods

This study aims to investigate the antioxidant properties and physical stability of convection‐ or vacuum‐dried orange, yellow and purple sweet potato (Ipomoea batatas) powder upon room temperature storage at different relative humidity (RH) of 33%, 43%, 54% and 75% for 25 days. Both convection and vacuum‐dried samples had lower total phenolic content (TPC), anthocyanin content and antioxidant activity compared to the fresh samples. Vacuum‐dried powder retained higher antioxidant activity than convection‐dried powder. Storage of the powder at high RH of 75% resulted in apparent clump formation, which was likely attributed to the decrease of glass transition temperature (T_g). In general, purple sweet potato powder contained the highest TPC (255.0 mg GAE 100 g DW^?1) and antioxidant activity (1924.0 μmol TEAC 100 g DW^?1), while orange powder had the highest beta‐carotene content (127.2 mg 100 g DW^?1). Vacuum‐dried sweet potato powder, which has relatively higher antioxidant activity, could be a potential functional ingredient or natural colourant for the food industry.     

Microbial inactivation and quality improvement of tomatoes treated by package film with allyl isothiocyanate vapour

In‐package sanitisation was developed using polylactic acid (PLA) films with allyl isothiocyanate (AIT) vapour. Tomatoes were artificially inoculated with Escherichia coli, Geotrichum candidum and Fusarium oxysporum and stored in clamshell boxes with the film fixed to the underside of the lid. The changes in bacterial and fungal populations and the quality of tomatoes during storage at 4 and 10 °C were evaluated. The results revealed that the film treatment (4 × 8 cm² film in 1 L box) reduced the populations of inoculated bacteria and fungi on tomatoes by 2–3 log CFU g^?1, and then significantly (P < 0.05) inhibited their growth during the 21‐day storage period at both temperatures. Tomatoes subject to film treatment had fewer changes in quality (colour, firmness, contents of total soluble solid, titratable acids and vitamin C) than the control samples during storage. The antimicrobial PLA film can be used for in‐package sanitisation to extend the shelf‐life of packaged tomatoes or similar perishable vegetables.     

Phytochemicals and quality characteristics of candied paprika (Capsicum annuum L.) during storage

In this study, we prepared candied paprika from various coloured fresh paprika and compared the changes in phytochemicals and quality for 42 days by analysing carotenoids, ascorbic acids and total phenolic content, and by assessing sensory and instrumental qualities. We identified five types of carotenoids from candied red paprika (CRP) and three from candied orange paprika (COP) and candied yellow paprika (CYP). At 0‐day storage, capsanthin and β‐carotene in CRP were quantitatively analysed to 26.96 μg g^?1 fw and 3.81 μg g^?1 fw, zeaxanthin and β‐carotene in COP were 9.35 μg g^?1 fw and 4.16 μg g^?1 fw, and lutein and β‐carotene in CYP were 0.27 μg 100 g^?1 fw and 0.70 μg 100 g^?1 fw, respectively. After 42‐days storage, CRP retained approximately 68.6% carotenoids, COP retained 40%, and CYP retained 33%. Ascorbic acid and total phenolic content decreased during storage as carotenoids did. However, rates of decrease were different in different coloured paprika, especially, ascorbic acid in COP and phenolic acid in CRP were considerably conserved for 42 days. Hardness, springiness and chewiness in all samples were significantly increased by 14‐days storage and maintained until 42‐days storage, and all the sensory parameters, including colour, appearance, odour, texture, paprika flavour and overall consumer preference showed no differences until 28 days.     

Oxidative enzymes and functional quality of minimally processed grape berries sanitised with ozonated water

Thompson Seedless (TS) and Black (BS) grapes sanitised with 2, 4, 6, 8 mg L^?1 O₃ or NaOCl (100 mg L^?1) were stored 21 days at 5 °C. Ozonated water stimulated the respiration rate, especially after 5 days of storage, and increased superoxide dismutase and catalase activity compared to NaOCl‐sanitised grapes. Total polyphenol content (TPC) was 23–50% higher in TS and 18.5–28% higher in BS samples sanitised with ozonated water. Twofold higher total antioxidant capacity (TAC) was registered in TS at all of the evaluated O₃ doses while the doses of 6 and 8 mg L^?1 increased TAC by 19–30% in BS. The use of ozonated water as a sanitising method, especially at 6 and 8 mg L^?1 doses, improved the functional quality and maintained low microbial counts on fresh‐cut grapes being a good alternative for the industry.     

光线照射下芫荽和蕹菜常温贮藏效果比较

比较了芫荽(Coriandrum sativum L.)和蕹菜(Ipomoea aquatica Forsk)在20±1℃下光照处理的贮藏效果。在4d贮藏期内,用光合量子通量密度(PPED)为5μmol/m2•s的红光每天连续照射24h。结果表明,与黑暗条件下芫荽和蕹菜贮藏效果相比,光照有利于累积还原糖和减少叶绿素和VC损失,并且光照条件下蕹菜的贮藏效果好于芫荽;贮藏结束时,光照处理的芫荽和蕹菜中叶绿素含量分别比同期黑暗处理的高出76.82%和93.36%,还原糖含量分别高出32.69%和20.57%,VC保存率分别高出2.31和2.38倍;芫荽根部和蕹菜嫩茎切口吸收水分而使其保持鲜嫩状态,两者含水量变化与光照无关。     

Advances in the use of white light on broccoli and kale postharvest shelf life

In this work, the effect of irradiation with three different intensities of white light-emitting diodes (LED) on the quality and senescence of refrigerated broccoli and green and red kale was studied. A high increase in weight loss was observed in samples exposed to high (80 μmol m⁻² s⁻¹) and low (10 μmol m⁻² s⁻¹) LED intensity. Samples stored under mid-intensity (30 μmol m⁻² s⁻¹) significantly reduced the change of total color (∆E), hue angle, and lightness (L*) values. Broccoli florets and green kale subjected to mid-intensity illumination retained higher chlorophyll levels than the other treatments (P < 0.05), and about 30% more compared to the dark stored samples. These differences were even more evident in red kale. Mid-intensity illumination also markedly reduced sugar losses and improved carotenoid contents. As a whole, results show that the selected intensity of white light used for postharvest illumination has a key influence on treatment efficacy.Industrial relevancePostharvest shelf life of green vegetables is very limited and there is a need to use environmentally friendly tools to extend it. The use of white light during storage has been proven to be a clean and non-chemical methodology to delay vegetable senescence, but the appropriate illumination conditions to maximize the quality of unprocessed vegetables are still unknown. In the present work, the effect of different lighting conditions on the visual and nutraceutical quality of refrigerated broccoli and green and purple kale was studied, and the best condition was defined. The selected light intensity may be considered for fresh market storage.     

Changes in in vitro protein digestion of retort‐pouched pork belly during 120‐day storage

To investigate the effect of long‐term storage on in vitro protein digestion of the retort‐pouched pork belly. The products were stored at 25 °C for 0, 30, 60 and 120 days and digested with pepsin and trypsin at each time point. SDS‐PAGE and LC‐MS‐MS were applied to separate and identify proteins and their digested products. In vitro protein digestibility decreased from 47.7% after 60‐day storage to 25.4% after 120‐day storage for the samples digested by pepsin, and from 63.9% to 45.7% for the samples digested by pepsin and trypsin at corresponding time points. LC‐MS‐MS demonstrated changes in peptide composition and abundance with storage time. Long‐term storage could deteriorate nutritive values of meat products by reducing digestible protein content.