Suitability for minimal processing of non‐melting clingstone peaches

Clingstone non‐melting peach cultivars (Prunus persica L. Batsch) are used primarily for canning, but their processing as fresh‐cut products is also of interest. Four clingstone peach cultivars (‘Andross’, ‘Babygold 8′, ‘Calante’ and ‘Romea’) were evaluated for their suitability for minimal processing (washing, peeling and slicing) followed by storage for 9 days at 4 °C in a modified atmosphere using microperforated films. Romea cultivar, which has low polyphenol oxidase (PPO) enzymatic activity, proved to be the most suitable cultivar for minimal processing, given its lower degree of browning as well as the results from a sensory evaluation. Maturity indicators varied slightly during storage at a different degree depending on cultivars. We have found that PPO activity and browning potential are adequate indicators for surface browning in fresh‐cut non‐melting peaches.     

Screening quality and browning susceptibility of five artichoke cultivars for fresh‐cut processing

BACKGROUND: Artichoke is a rich source of bioactive compounds, mainly phenols, in the Mediterranean diet, but its consumption is limited by the complexity of time‐consuming trimming operations. Fresh‐cut processing would therefore add convenience to its consumption, even though the severity of post‐cutting browning of artichoke pieces is still a major problem. Since susceptibility to browning may vary widely among genotypes, the choice of the cultivar is a very critical step in the fresh‐cut process. In this study, five different Italian cultivars (C3, Catanese, Tema, Violetto Foggiano and Violetto Sardo) were screened for their initial quality and composition, and their post‐cutting performance during storage at 5 °C and 20 °C. RESULTS: C3 showed the highest phenol content (3.4 g GA kg^?1) and antioxidant activity (24.5 mmol L^?1 kg^?1), but the worst quality in terms of appearance and colour changes, also due to its high PPO activity (62.2 U g^?1). Catanese showed the highest vitamin C content (117.7 mg kg^?1), the lowest phenol content (1.8 g GA kg^?1), and the best post‐cutting quality. Tema, Violetto Foggiano and Violetto Sardo showed an intermediate phenol content, the latter showing the lowest appearance score after C3. CONCLUSION: These results confirmed the role of phenols in browning processes of fresh‐cut artichokes, giving the first available information on artichoke cultivar suitability to be processed as a fresh‐cut product. Copyright © 2009 Society of Chemical Industry     

Effect of minimal processing on the textural and structural properties of fresh‐cut pears

The feasibility of minimal processing and modified atmosphere packaging to preserve the original textural quality of fresh‐cut pears was evaluated throughout storage under refrigeration. Fresh‐cut pear firmness could be extended up to several weeks with low‐O₂ atmospheres. A packaging atmosphere of 100% N₂ combined with the use of plastic bags with an O₂ permeability of 15 cm³ m^?2 bar^?1 day^?1 maintained cell structure and partially avoided membrane breakdown and exudate accumulation in intercellular spaces. Under the other conditions studied, pear texture underwent dramatic deterioration, which could be related to complete inundation of the extracellular environment. Firmness decreased linearly throughout the storage period studied, with rate constants ranging from 0.0097 to 0.040 day^?1. The consideration of other textural variables also gave valuable information, similar to that provided by firmness data. © 2002 Society of Chemical Industry     

Microbiological hazards involved in fresh‐cut lettuce processing

BACKGROUND: The increasing consumption of produce all over the world has resulted in increasing concern by the regulatory agencies with respect to the level of safety performed by the processors. The objective of the present study was to investigate the hazards involved in the various steps of fresh‐cut lettuce processing (reception/selection of raw material, washing, rinsing, sanitisation and final product) by means of microbiological analyses of microbial groups used as indicators of hygienic conditions and of pathogens. RESULTS: High microbial loads of mesophilic and psychrotrophic bacteria and Pseudomonas spp. were found in the ram reception (～6 log colony‐forming units (CFU) g^?1), which were reduced by a single logarithmic cycle for the last two microbial groups after the sanitisation step (P < 0.05), the latter being ineffective against the first microbial group (P > 0.05). Lower counts of yeasts and moulds, total coliforms (35 °C) and faecal coliforms (44 °C) were observed in the initial step (3.49–4.53 log CFU g^?1, 0.65–1.55 log most probable number (MPN) g^?1 and 0.50–0.90 log MPN g^?1 respectively), these values increasing significantly after the sanitisation step for yeasts and moulds (～5 log CFU g^?1) but remaining unaltered for coliforms (P > 0.05). Salmonella spp. were not found in any of the experiments carried out, while the presence of Escherichia coli was observed in the final product. CONCLUSIONS : Practices compromising the hygienic quality of the final product during commercial storage were observed and corrective measures suggested. To the best of the authors' knowledge, these are the first data on microbiological safety in Brazilian fresh‐cut processing plants. Copyright © 2008 Society of Chemical Industry     

Modelling changes in anthocyanins,total vitamin C and colour as a consequence of peracetic acid washing disinfection of two cultivars of strawberries for fresh‐cut processing

The aim of the study was to quantify and model the retention of total anthocyanins (TAR), ascorbic acid (AAR) and total vitamin C (Vit C), and the colour changes of fresh‐cut strawberries after washing disinfection with peracetic acid (PAA) at different concentrations (0–100 mg L^?1), times (10–120 s) and temperatures (4–40 °C). Two strawberry cultivars (Camarosa and Selva) were used. TAR (%) and AAR (%) were principally affected by PAA concentration and processing time in both cultivars. There was an approximately 90% Vit C retention at any condition in the experimental domain for Camarosa cultivar. However, in the case of Selva cultivar, total vitamin C retention and colour changes were affected by the processing variables.     

Browning inhibition on fresh‐cut chestnut kernel by exogenous nitric oxide

The potential usage of nitric oxide (NO) as a powerful anti‐browning agent in fresh‐cut chestnut kernels was investigated. Chestnut kernels were dipped in 0, 1, 5 or 10 μm NO solutions for 10 min, respectively, and then stored at 20 °C. Changes of browning index and colour were evaluated, while content of total phenols, activities of polyphenol oxidase (PPO) and peroxidase (POD) and individual phenolic compounds were measured. The results showed that NO treatment delayed browning and lightness of chestnut kernels and 5 μm NO treatment had the best control effect compared with others. PPO and POD activities were inhibited and total phenolic content was increased in NO‐treated fruit, and 5 μm NO significantly increased the content of catechin, chlorogenic acid, syringic acid, phloretic acid and ferulic acid but inhibited that of tannic acid. However, it had no significant effect on caffeic acid.     

Antioxidant properties and shelf‐life extension of fresh‐cut tomatoes stored at different temperatures

BACKGROUND: The feasibility of using modified atmosphere packaging (5 kPa O₂ + 5 kPa CO₂) to maintain the antioxidant properties of fresh‐cut tomatoes during shelf‐life was assessed through storage at different temperatures (5, 10, 15 and 20 °C). Health‐related compounds, antioxidant capacity, microbiological counts, physicochemical parameters and in‐package atmosphere of tomato slices were determined. RESULTS: Initial lycopene, vitamin C and phenolic contents and physicochemical parameters of tomato slices were well maintained for 14 days at 5 °C. Lycopene and total phenolic contents were enhanced over time in tomato slices stored at 15 and 20 °C. However, this increase in antioxidant compounds of fresh‐cut tomatoes during storage may be associated with excessive amounts of CO₂ (R² = 0.5679–0.7328) in the packages due to microbial growth. Although keeping tomato slices at temperatures above 10 °C increased their antioxidant content, the shelf‐life of the product was reduced by up 4 days. CONCLUSIONS: A storage temperature of 5 °C is appropriate for maintaining the microbiological shelf‐life of fresh‐cut tomatoes for up to 14 days and also allows the antioxidant properties of tomato slices to be retained over this period, thus reducing wounding stress and deteriorative changes. Copyright © 2008 Society of Chemical Industry     

The effect of calcium chloride and calcium lactate pretreatment concentration on peach cell integrity after high‐pressure processing

The objective of this study was to determine the effect of calcium chloride and calcium lactate pretreatments at different concentrations (1, 1.5 and 2% w/v) on enzymatic browning of clingstone and freestone peaches following high‐pressure processing (HPP) at 200 MPa for 10 min. Proton nuclear magnetic resonance (¹H‐NMR) relaxometry indicated that following calcium pretreatment and HPP, both peach types had lower percentages of water in the vacuole compartment and a simultaneous increase in the percentage of water in the cytoplasm compartment. Calcium pretreatment of freestone peaches did not affect the development of browning, regardless of the form of calcium or the concentration, whereas calcium lactate pretreatment undesirably enhanced clingstone peach discoloration. Calcium pretreatments have the potential to reduce the loss of cell integrity that results from HPP; however, in this study, the effect was not sufficient to inhibit the interaction between the polyphenol oxidase enzyme that catalyses browning and its substrates.     

Optimization of processing of fresh‐cut pear

BACKGROUND: Successful processing of pears to render fresh‐cut fruits requires a thorough knowledge of their sensitivity to browning reactions, their respiratory metabolism, and their behaviour under modified atmosphere packaging. RESULTS: First, three different varieties of pear (Williams, Conference, Passacrassana) that had reached their commercial ripening stage were evaluated for suitability for minimal processing. Two antioxidant treatments were tested (treatment 1: 2% ascorbic acid + 1% citric acid + 1% CaCl₂; treatment 2: 2% ascorbic acid + 0.01% 4‐hexylresorcinol + 1% CaCl₂) to decide which one was the most effective against enzymatic browning. Finally, a modified atmosphere packaging was designed after two previous tests: measurement of respiratory activity of the peeled and cut pear at three temperatures (4, 15 and 25 °C); and evaluation of fruit tolerance to three different atmospheric compositions (21% O₂ + 10% CO₂; 2% O₂ + 0% CO₂; 2% O₂ + 10% CO₂). CONCLUSIONS: Conference pear was found to be the most suitable variety. Among the antioxidant treatments the one consisting of ascorbic acid, 4‐hexylresorcinol and CaCl₂ was proven to be the most effective against browning. The samples were packaged in a modified atmosphere with a composition of 10% O₂ + 10% CO₂ + 80% N₂. Copyright © 2008 Society of Chemical Industry     

Improving the quality of fresh‐cut melon through inactivation of degradative oxidase and pectinase enzymatic activities by UV‐C treatment

This work investigated the effect of exposure of fresh‐cut melon (Cucumis melo L. var. reticulatus) to ultraviolet‐C (UV‐C, 254 nm, 0.04 kJ s^?1 m^?2) radiation for different times (30, 60, 120 s) on main degradative enzymatic activities (polyphenol oxidase, peroxidase, pectin methylesterase and polygalacturonase) and quality parameters (firmness, colour) during storage at 5 °C. Enzymatic activities in samples washed with water and treated with UV‐C radiation were similar to samples washed with 100 mg L^?1 NaOCl and significantly lower than untreated samples, especially after 7 days of storage at 5 °C. Tissue softening was noticed in all samples although those treated with UV‐C light resulted 7–12% firmer than untreated ones. The lowest perceptible colour variation, expressed as ΔE*, was in samples exposed to 120 s radiation (ΔE = 8.58), while the highest value was noticed in untreated sample (ΔE = 11.06). Postcut UV‐C fruit treatment was effective in extending the shelf life of minimally processed ‘Galia’ melon.     

Hot water,UV‐C and superatmospheric oxygen packaging as hurdle techniques for maintaining overall quality of fresh‐cut pomegranate arils

BACKGROUND: In recent years there has been increasing consumer pressure to avoid the use of agrochemicals such as chlorine on fresh plant products for extending their shelf life. The combined use of eco‐sustainable techniques may be an alternative. The effect of hot water (HW), ultraviolet‐C (UV‐C) light and high oxygen packaging (HO) on the overall quality of fresh‐cut pomegranate arils stored under modified atmosphere packaging (MAP) for up to 14 days at 5 °C was studied. RESULTS: Arils extracted manually, washed with chlorine (100 µL L^?1 NaClO, pH 6.5, 5 °C water), rinsed and drained were exposed to single or combined (double and triple) hurdle techniques. The HW treatment consisted of a 30 s immersion in water at 55 °C followed by air surface drying. A 4.54 kJ m^?2 dose was used for the UV‐C treatment before packaging. Active MAP with initial 90 kPa O₂ was used in the HO treatment. The respiration rate remained relatively constant throughout shelf life, with no differences among treatments. CO₂ accumulation was higher within HO packages. HW induced a slight reduction in total soluble solids, while no changes in titratable acidity were found. HO‐treated arils had the highest phenolic content, while the lowest was found in HW‐treated arils. The lowest antioxidant activity was found in HW + UV‐C + HO and the highest in UV‐C + HO and HO treatments. HW alone or in combination with UV‐C and HO inhibited mesophile, mould and yeast growth, while UV‐C + HO was most effective for controlling yeast and mould growth. CONCLUSION: UV‐C and HO either alone or in combination are promising techniques to preserve the quality of pomegranate arils for up to 14 days at 5 °C. © 2012 Society of Chemical Industry     

不同品种桑椹加工品质比较研究

该实验对四川地区8种不同品种桑椹的出汁率、pH值、可滴定酸、可溶性总糖、还原糖、糖酸比、密度及原花青素等多种指标 进行分析,并对各指标进行主成分分析（PCA）和系统聚类分析（CA）。结果显示,8个品种的品质指标差异较大,桑椹品种无核大十的 出汁率最高（75.25%）,且原花青素含量最高（0.674 g/100 g）。主成分分析结果表明对桑椹加工品质影响最大的是糖酸比、可溶性总糖 及密度,方差累计贡献率为92.58%。 桑椹品种无核大十最适宜深加工,德果1号、台湾四季桑及嘉陵30号等桑椹品种次之。     

Influence of hot‐air treatment,superatmospheric O2 and elevated CO2 on bioactive compounds and storage properties of fresh‐cut pomegranate arils

The impact of heat treatment using hot air (HT 45 °C and 55 °C for 1 h) and two active modified atmosphere packaging (MAP) conditions of high oxygen atmosphere (HOA: 80 kPa O₂, 20 kPa N₂) and high CO₂ atmosphere (HCA: 20 kPa CO₂, 80 kPa N₂), individually or combined, on the antioxidant capacity, polyphenols, vitamin C content, total anthocyanins, polyphenoloxydase (PPO) activity and shelf life of fresh‐cut (FC) pomegranate arils stored for 14 days at 4 °C was studied. The results indicate that HT 45 °C along with HOA inhibited PPO activity and prevented loss of antioxidant capacity, vitamin C and phenolic compounds in arils, in comparison with control and HT 55 °C. All treatments reduced the accumulation of anthocyanins, but HCA‐treated arils lost more anthocyanins besides having worse a* colour parameter values. No significant differences in titrable acidity (TA) and total soluble solids (TSS) were observed between treatments. The combination of HOA and HT 45 °C enhanced the benefits of applying each treatment separately and could be useful to improve and extend postharvest life of pomegranate FC arils.     

Reassessment of treatments to retard browning of fresh‐cut Russet potato with emphasis on controlled atmospheres and low concentrations of bisulphite

The cultivar Pacific Russet with high browning susceptibility was used for most testing. Controlled atmospheres (0.3%, 3% and 21% O₂ in combination with 0%, 6% or 12% CO₂) and anti‐browning chemicals were studied in relation to quality retention and wound‐induced phenolic metabolism of fresh‐cut slices for up to 16 days at 5 °C. The 3% O₂+ 12% CO₂ atmosphere was most effective among those tested, and retarded increases in phenolics and phenylalanine ammonia lyase activity, but had only slight benefit on visual quality. A 1.25% ascorbic acid +1.25% citric acid treatment was ineffective, but when combined with 3% O₂+ 12% CO₂, it was comparable with 0.025% sodium bisulphite. Bisulphite concentrations from 0.05% to 0.25% provided similar effective control of discolouration. Bisulphite as low as 0.025% with 3% O₂+ 12% CO₂ resulted in a visual quality score at the limit of marketability after 8 days at 5 °C. Chemical treatments did not retard increases in phenolic concentrations or phenolic enzyme activities.     

基于GC-MS和PCA对怒江州4个主要产地及不同加工方式漆油成分分析

为研究怒江州不同产地漆油成分差异,比较传统工艺(手工)和现代工艺(机器压榨)制取漆油的优缺点,了解白漆油和黑漆油的区别,找到漆油中除脂肪酸外其他功能性成分,采用气相色谱-质谱(GC-MS)联用技术对怒江州漆油成分进行测定,并结合主成分分析(PCA)对怒江州4个不同产地漆油脂肪酸组成及含量进行分析。结果表明:怒江州4个不同产地漆油脂肪酸组成主要为饱和脂肪酸,其含量差异显著,泸水产地的漆油品质较优;传统工艺与现代工艺制取的漆油脂肪酸含量差异显著,但两种工艺各具优点;白漆油脂肪酸含量和黑漆油相差不大;从4个不同产地漆油样品中还检测到了壬二酸、十七烯、角鲨烯,其在工业生产、医疗保健等方面都具有重要作用。     

Quality of fresh‐cut baby spinach grown under a floating trays system as affected by nitrogen fertilisation and innovative packaging treatments

BACKGROUND: Alternative techniques for cultivation of leafy vegetables such as a floating tray system and unconventional gas mixtures for post‐harvest active modified atmosphere packaging (MAP) could be of interest in the minimally processed vegetable industry. RESULTS: The combined effect of three pre‐harvest fertilisation doses (8, 12 or 16 mmol N L^?1) and three post‐harvest MAP conditions (passive, super‐atmospheric or N₂O‐enriched) on the main quality attributes of fresh‐cut baby spinach leaves throughout 10 days at 5 °C was studied. After 8 days of shelf life, spinach leaves fertilised with 8 and 16 mmol N L^?1 and stored under N₂O‐enriched MAP showed the lowest microbial growth, with good sensory quality. Such combined treatments also preserved the total antioxidant capacity sampled at harvest (8 g ascorbic acid equivalent antioxidant capacity kg^?1 f.w.). A decrease of 10–20% in total vitamin C content regardless of N fertilisation and packaging treatment was found during shelf life. Total phenolics content at harvest was 2 g gallic acid equivalents kg^?1 f.w., which was slightly decreased or preserved during shelf life while total chlorophylls were preserved for all treatments assayed around 550 mg kg^?1 f.w. CONCLUSION: No clear effect of fertilisation doses was observed during post‐harvest storage on overall quality of fresh‐cut baby spinach leaves, while N₂O‐enriched atmospheres seems to be a promising alternative to passive MAP for extending shelf life. Copyright © 2010 Society of Chemical Industry