壳聚糖涂膜对鲜切苹果品质的影响

以山东红富士苹果为原材料,研究了不同浓度复合的壳聚糖、抗坏血酸及柠檬酸对鲜切苹果的外观和内部品质的影响。采用L9(34)正交实验设计,测定了贮藏过程中各组鲜切苹果的腐烂率、色泽、pH、可滴定酸、还原性糖等指标的变化情况。根据模糊权重法对贮藏4d的鲜切苹果外观和内部品质进行了综合评定。结果表明:选用2.0%柠檬酸、1.0%壳聚糖配制涂膜液和0.5%抗坏血酸溶液作为护色液,对鲜切苹果具有良好的保鲜效果。     

Postharvest Physiology and Quality Maintenance of Sliced Pear and Strawberry Fruits

Sliced strawberries (cvs.‘Pajaro’ and 'G-3′) and partially ripe pears (cv.‘Bartlett’) were dipped in various solutions (citric acid, ascorbic acid, and/or calcium chloride) and stored in air or in controlled atmospheres (CA) for 7 days at 2.5°C followed by one day at 20°C. Fruit slices respired at a higher rate than whole fruits at both temperatures. CA storage suppressed respiration and ethylene production rates of sliced fruits. Firmness of strawberry and pear slices was maintained by storage in air + 12% CO₂ and in a 0.5% O₂ atmosphere, respectively, or by dipping in 1% calcium chloride. These treatments also resulted in lighter colored pear slices than the air control treatment.     

Effects of Anti-browning Combinations of Ascorbic Acid, Citric Acid, Nitrogen and Carbon Dioxide on the Quality of Banana Smoothies

The effects of 0.2 % ascorbic acid?+?0.2 % citric acid (AA?+?CA), 0.2 % ascorbic acid?+?0.2 % citric acid?+?N₂ (AA?+?CA?+?N₂) and 0.2 % ascorbic acid?+?0.2 % citric acid?+?CO₂ (AA?+?CA?+?CO₂) on the quality of banana smoothies were investigated. An obvious anti-browning effect was observed after each treatment, which resulted from a significant decrease in the polyphenol oxidase activity (p?<?0.05) and the exclusion of oxygen by infusion with inert N₂ or CO₂. The AA?+?CA?+?N₂ treatment exhibited the lowest change of browning index (ΔBI) indicating the best anti-browning effect on the banana smoothies. Compared with the Herschel–Bulkley model, the Power Law was less complex and more suitable for describing the rheological properties of the banana smoothies. AA?+?CA, AA?+?CA?+?N₂ and AA?+?CA?+?CO₂ treatments all significantly increased the pectin methylesterase activity of the banana smoothies (p?<?0.05). The AA?+?CA treatment increased the cumulative volume of the larger particles in the banana smoothies. The viscosity of the banana smoothies decreased after the three different treatments. In terms of the comprehensive results, the inclusion of AA?+?CA?+?N₂ in the production of banana smoothies was the best processing method applied.     

Effect of Natural Antibrowning Agents on Color and Related Enzymes in Fresh-Cut Fuji Apples as an Alternative to the Use of Ascorbic Acid

ABSTRACT:  Polyphenoloxidase (PPO) and peroxidase (POD) were evaluated in fresh-cut Fuji apple slices and the effect of the individual or combined use of ascorbic acid, 4-hexylresorcinol, N-acetylcysteine, and glutathione on their respective activities was determined. Additionally, color changes during storage at 4 °C were measured throughout 14 d of storage. PPO activity increased with storage time and was inhibited by the individual use of N-acetylcysteine and glutathione. POD activity in the apple slices was effectively inhibited by the combined use of ascorbic acid with any of the other antibrowning agents. On the other hand, an individual treatment with 1% N-acetylcysteine helped in maintaining the color of fresh-cut apples during 14 d of storage, whereas the use of ascorbic acid was not enough to prevent color deterioration of the apple slices from the 1st day of storage. The results obtained corroborated the effectiveness of other natural antibrowning agents over the traditional use of ascorbic acid in the control of the enzymatic browning in the fresh-cut fruit industry.     

曲酸、抗坏血酸及柠檬酸对鲜切苹果褐变的影响

以鲜切苹果为试材,分别用曲酸、抗坏血酸和柠檬酸浸泡3 min,于4℃存放9 d,对鲜切苹果的硬度、色泽、总酚、可溶性醌、多酚氧化酶活性、维生素C等指标进行分析。结果表明,3种有机酸对鲜切苹果的硬度和多酚氧化酶的影响差异不显著(P>0.05),而对褐变、总酚和维生素C影响差异显著(P<0.05)。综合来看,3种有机酸均对鲜切苹果褐变都有抑制效果,而曲酸明显优于柠檬酸和抗坏血酸,说明曲酸是一种潜在的鲜切苹果保鲜和护色剂。     

柠檬酸处理对鲜切苹果的保鲜效果

为研究柠檬酸处理对鲜切苹果品质的影响,将鲜切‘寒富’苹果分别放入0.5%、1.0%、1.5%柠檬酸溶液中浸泡2 min后沥干,用0.11 mm厚度的聚乙烯保鲜膜包装后置于4 ℃冷库中贮藏,每2 d检测与成熟衰老相关生理生化指标。结果表明,适当质量分数的柠檬酸处理可保持苹果切块的感官品质,延缓营养物质的下降,抑制微生物的繁殖,对鲜切苹果有较好的护色效果;1.5%柠檬酸溶液浸泡处理能在8 d贮藏期内4 ℃冷藏条件下保持着鲜切苹果的良好品质,能有效延迟果肉褐化进程,降低褐变程度,抑制硬度和可溶性固形物、可滴定酸及抗坏血酸含量的下降,并能延缓相对电导率和丙二醛含量的上升,降低多酚氧化酶、过氧化物酶的活性。     

POLYPHENOLOXIDASE ACTIVITY OF MINIMALLY PROCESSED 'JONAGORED' APPLES (MALUS DOMESTICA)

The influence of three chemical dips using ascorbic acid (AA), citric acid (CA) and calcium chloride (CC) on the polyphenoloxidase (PPO) activity and on the total phenolic content of minimally processed (MP) apple (Malus domestica, cv. Jonagored) during cold storage was evaluated and a potential relationship with enzymatic browning was investigated. An ascorbic acid dip (42.6 mM) of 5 min duration was the most efficient chemical treatment in reducing the PPO activity of apple cubes. A 92% inhibition was achieved after 7 days of storage at 4C. All treatments were advantageous in comparison to the control in reducing color changes. Color changes, determined by absorbance at 420 nm (soluble pigments) and lightness (L) (insoluble pigments) of apple cubes treated with ascorbic acid were correlated with total phenolic content. No correlation was observed between PPO activity and tristimulus color parameters, browning index or total phenolic content of AA‐treated apple cubes.     

QUALITY OF APPLE SLICES PROCESSED BY COMBINED TECHNIQUES

The effectiveness of single pretreatments and combinations of pretreatments on the prevention of enzymatic browning during freezing and thawing of apple slices was investigated. The combinations of blanching and dipping, either of which alone could not control enzyme activity, were studied. Blanching of apple slices caused a significant decrease of firmness even before the freezing-thawing phase. The use of a “light” dip after a short blanch allowed the product to be cooled and helped the antioxidant agents (ascorbic and citric acids) to enter apple tissue. The anti-browning action of sodium chloride, even at very low levels in dipping solutions, was confirmed. Partial drying avoided the loss of firmness but negatively affected the color. “Mild pretreatments”, including partial drying, gave satisfactory results in terms of firmness and color.     

Quality of Fresh-cut Apple Slices as Affected by Low-dose Ionizing Radiation and Calcium Ascorbate Treatment

ABSTRACT: Although ionizing radiation effectively inactivates food-borne bacterial pathogens in fresh-cut fruits and vegetables, it may adversely affect product quality. In this study, the effects of calcium ascorbate (CaA) and ionizing radiation on quality of 'Gala' apple slices under modified atmosphere packaging were investigated. 'Gala' apple slices, treated with water or 7% CaA followed by either nonirradiation (0 kGy) or irradiation at 0.5 and 1.0 kGy, were stored at 10°C for up to 3 wk. The titratable acidity, pH, firmness, ascorbic acid content, color, and microflora population were measured weekly throughout storage. Irradiation did not affect titratable acidity and pH of sliced apples. Fruit slices softened during irradiation and storage, but this decrease in firmness during storage was reduced by the CaA treatment. Although the ascorbic acid content of apple slices treated with CaA decreased rapidly during storage, the ascorbic acid content was always higher in those treated samples than in the apple slices treated with water. Irradiation decreased both L * and hue values of apple slices. Hue values decreased during the entire storage period while L * increased during the 1st wk of storage, then decreased between 1 to 3 wk of storage. CaA increased L * and hue values of apple slices, suggesting CaA reduced browning, even in irradiated samples. The microflora population of apples slices was not affected by CaA, and CaA treatment did not alter the reduction in microflora by irradiation. The combination of CaA and irradiation enhanced microbial food safety while maintaining quality of fresh-cut apple slices.     

Effect of fluidized bed drying on properties of dehydrated apples

Three sorts of apple (Idared, Golden Delicious and Jonathan) were dried in a laboratory-type fluidized bed dryer. Apples were cleaned, cored, peeled and cut into 10 × 10 × 10 mm cubes or into slices 5 × 3 mm thick and 40 mm long. A part of the samples was dipped for 3 min prior to drying in 0.1% ascorbic acid solution. Drying temperature was 80 °C. Some physicochemical and sensory properties of fresh and dried apples were determined. Moisture content in dried samples varied between 9 and 12%. Greater quantity of water results in lower sensory characteristics. The sensory characteristics of apples were determined by a scoring system with weighed factors in a 20-point scale. Glucose, fructose, saccharose, citric acid, malic acid and ascorbic acid levels were analysed by enzymatic methods. Contents of glucose, fructose and saccharose in dried apples were substantially unchanged compared to fresh apples. The drying process had the most influence on contents of citric and malic acids. Higher rehydration ratios were measured in spaghetti-like sclices and in ascorbic acid treated samples. Idared had the best characteristics with regard to physicochemical and sensory results.     

褐变抑制剂对干制香蕉片护色效果的影响

为了提高香蕉片干制后的颜色品质,获得最佳护色方法,以褐变度和L*值为考察指标,研究植酸、抗坏血酸、氯化钠、EDTA、柠檬酸5种褐变抑制剂对干制香蕉片颜色品质影响,并优选出提高干制香蕉片颜色品质的护色方法。结果表明:单一护色剂护色效果依次为植酸柠檬酸EDTA氯化钠抗坏血酸,将鲜切香蕉片放入植酸(质量分数为0.9%)和柠檬酸(质量分数为0.3%)组成的复合护色液中浸泡20 min,干制后的香蕉片L*值达65.93,褐变抑制率达84.4%。     

INFLUENCE OF CHEMICAL TREATMENT ON QUALITY OF CUT APPLE (cv. JONAGORED)

The quality of a new variety of apple, ‘Jonagored’, after peeling and cutting was evaluated during ten days of storage in air at 4C. The objective was to evaluate the shelf-life of apple cubes by detecting the limiting parameter and to test the influence of different chemical dips on the cut apple quality with the aim of extending shelf-life. Color, i.e. browning at the cut surface, was found to be the critical quality parameter determining the shelf-life of the cut apple to less than three days. There were no significant differences between the dip treatments in measurements of CIE values. When apple cubes were treated with ascorbic acid, ascorbic acid plus calcium chloride or ascorbic acid plus calcium chloride and citric acid, the 0.75% ascorbic acid dip was found to be the most effective preservation treatment in terms of reducing color change of the cut surface. Both 0.75% ascorbic acid and 0.75% ascorbic acid plus 0.75% calcium chloride inhibited the loss of firmness of apple cubes. When citric acid was added to the dip treatment, there were color changes similar to those of the control.     

可食性复合涂膜保鲜剂对延长鲜切苹果货架期的研究

本文主要研究了可食性涂膜剂与抗褐变剂复配后对鲜切苹果的保鲜效果。研究表明:25℃条件下,苹果切块经卡拉胶(0.5%)涂膜剂和乳清浓缩蛋白WPC(5%)涂膜剂处理后,其呼吸强度可分别降低5%和20%。在可食性涂膜剂中添加不同的抗褐变剂对苹果切块有良好的护色效果,添加1%CaCl2可增加产品的硬度,同时这些复合保鲜剂可提高苹果切块的感官指标和抑制微生物繁殖,而5%WPC涂膜液+1%CaCl2+1%抗坏血酸复合液浸泡苹果切块,3℃条件下贮藏2w后保鲜效果最佳。     

紫外线照射与柠檬酸处理对鲜切苹果的保鲜作用

目的研究柠檬酸、紫外线照射、柠檬酸和紫外线照射联合处理对鲜切苹果生理生化的影响。方法以富士苹果为实验材料,分成4组,分别是0.5%柠檬酸(CA)溶液中浸泡5 min、紫外照射(UV)5 min/面、0.5%柠檬酸溶液中浸泡5 min+紫外照射(CA+UV)5 min/面、不处理的对照组(KB)。分别于0、1、3、5、7、10、13、15 d测定鲜切苹果的色差、多酚氧化酶(PPO)、过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)活性。结果富士苹果经过切分后,褐变严重。PPO、POD活性升高,PAL活性变化曲折,总体呈上升趋势。柠檬酸、紫外、柠檬酸和紫外联合处理的3三种处理方式都可以抑制鲜切苹果的褐变,降低PPO、POD、PAL的活性。在4种处理方法比较中,柠檬酸和紫外联合处理的效果比较好。结论柠檬酸和紫外联合处理是鲜切苹果的理想的保鲜方法。     

Osmotic dehydration of guava: influence of replacing sodium metabisulphite with honey on quality

Guava slices were subjected to pre-treatment by soaking in a solution containing 0.25% (w/v) sodium metabisulphite, 0.5% (w/v) ascorbic acid, 1% (w/v) citric acid, 1% (w/v) calcium chloride and either 0%, 1% or 3% (v/v) honey. A higher concentration of metabisulphite [0.5% (w/v)], but no honey, was also prepared as a reference. After osmotic dehydration, the guava slices were dried at 60 °C. During 24 weeks of storage, the measured texture values of products indicated that an addition of honey significantly delayed the increase in hardness and cutting work in guava slices compared to other treatments ( P  ≤   0.05). Pre-treatment with 0.5% (w/v) metabisulphite without honey or 0.25% (w/v) metabisulphite with 1% (v/v) honey maintained colour during storage better than with 0 or 3% (v/v) honey. The result showed good agreement with colour score evaluation. Overall results suggested that 1% (v/v) honey was the best pre-treatment condition.     

Antibrowning and Antimicrobial Properties of Sodium Acid Sulfate in Apple Slices

ABSTRACT: There are few available compounds that can both control browning and enhance microbial safety of fresh‐cut fruits. In the present study, the antibrowning ability of sodium acid sulfate (SAS) on “Granny Smith” apple slices was first investigated in terms of optimum concentration and treatment time. In a separate experiment, the apple slices were treated with water or 3% of SAS, calcium ascorbate, citric acid, or acidified calcium sulfate for 5 min. Total plate count, color, firmness, and tissue damage were assessed during a 21‐d storage at 4 °C. Results showed that the efficacy of SAS in inhibiting browning of apple slices increased with increasing concentration. A minimum 3% of SAS was needed to achieve 14 d of shelf life. Firmness was not significantly affected by SAS at 3% or lower concentrations. Antibrowning potential of SAS was similar for all treatment times ranging from 2 to 10 min. However, SAS caused some skin discoloration of apple slices. When cut surface of apple slices were stained with a fluorescein diacetate solution, tissue damage could be observed under a microscope even though visual damage was not evident. Among the antibrowning agents tested, SAS was the most effective in inhibiting browning and microbial growth for the first 14 d. Total plate count of samples treated with 3% SAS was significantly lower than those treated with calcium ascorbate, a commonly used antibrowning agent. Our results suggested that it is possible to use SAS to control browning while inhibiting the growth of microorganisms on the apple slices if the skin damage can be minimized. Practical Application: Fresh‐cut apples have emerged as one of the popular products in restaurants, schools, and food service establishments as more consumers demand fresh, convenient, and nutritious foods. Processing of fresh‐cut apples induces mechanical damage to the fruit and exposes apple tissue to air, resulting in the development of undesirable tissue browning. The fresh‐cut industry currently uses antibrowning agents to prevent discoloration. However, the antibrowning solutions can become contaminated with human pathogens such as Listeria monocytogenes, and washing of apple slices with the contaminated solutions can result in the transfer of pathogens to the product. It would be ideal if an antibrowning compound prevented the proliferation of human pathogens in solutions and minimized the growth of pathogens during storage. The study was conducted to investigate antibrowning and antimicrobial properties of sodium acid sulfate (SAS) in comparison with other common antibrowning agents on Granny Smith apples. Results showed that among the antimicrobial agents we tested, SAS was the most effective in inhibiting browning and microbial growth for 14 d at 4 °C. However, SAS caused some skin discoloration of apple slices. Overall, SAS can potentially be used to inhibit tissue browning while reducing the microbial growth on apple slices. The information is useful for the fresh‐cut produce industry to enhance microbial safety of fresh‐cut apples while minimizing browning, thus increasing the consumption of the health benefiting fresh fruit.     

EFFECTS OF BRINING PRETREATMENT AND STORAGE ON CARAMBOLA (AVERRHOA CARAMBOLA L.) PICKLES

Mature, green carambola (Averrhoa carambola L.) were pretreated in 5, 10 or 15% NaCl for 24 h, hot-filled with vinegar, sucrose and spices, and pasteurized at 78 ± 1C for 15 min. No differences (P ≤ 0.05) in appearance, taste and texture were due to prebrining treatments, but most panelists (62%) preferred pickles in 10% brine. This pickle was stored either at 10C or 25C for 8 weeks. Some pickles had sodium benzoate (0.025%) or citric acid (1%) with ascorbic acid (0.25%) in pickling liquor. Interactions of treatments by storage resulted (P ≤ 0.05) in darkening of color, less greenness, more yellowness, softer texture, increase in pH and less than 10 CFU/g microbes in carambola pickles. Carambola slices with ascorbic acid and citric acid were the brightest and most green (P ≤ 0.05) after pickling and remained one of the least dark after storage (P ≤ 0.05). Storage of pickles at 10C minimized quality changes.     

MODELING THE SENSORY QUALITIES OF PROCESSED APPLES AFTER CONTROLLED ATMOSPHERE STORAGE AND FROZEN STORAGE1

Durational effects of controlled atmosphere storage (CA) and frozen storage on apple quality were studied for commercially processed pies made from Northern Spy, Idared and Nova Spy apples. Sensory tests on apple pie quality indicated that the duration of apples in CA significantly affected the quality of the processed apple. Extending the CA duration of the apples to 45 weeks resulted in a pie filling with reduced apple flavor, tartness and astringency, and with increased sweetness and off‐flavor. To minimize flavor/taste changes throughout the processing season, close attention must be given to the product's sugar/acid formulation: by week 27 for Idared apples and by week 33 for Northern Spy and Novaspy apples. The texture and appearance of processed Novaspy and Idared fruits were affected earlier in CA than Northern Spy apples. The frozen product was relatively stable for all three varieties, especially for apples processed early in the storage season (15–27 weeks). A strategy that utilizes short‐ to medium‐term CA with longer‐term frozen storage would optimize quality across the season.     

菠萝果汁抑制香蕉加工过程中酶褐变的初步研究

对菠萝果汁抑制香蕉片和香蕉果浆的酶褐变效果进行了研究。以蒸馏水、pH3.9柠檬酸溶液、10mmol/L异抗坏血酸溶液、5mmol/L亚硫酸氢钠溶液、新鲜菠萝果汁和热处理菠萝果汁分别对香蕉片和香蕉果浆进行处理,然后在不同时间测定香蕉片和香蕉果浆的L值。结果表明,新鲜菠萝果汁和热处理菠萝果汁具有相同的酶褐变抑制效果,而且显著优于蒸馏水、pH3.9柠檬酸溶液和10mmol/L异抗坏血酸溶液,与5mmol/L亚硫酸氢钠溶液的效果相似;其抑制酶褐变的机理不是单一的抗坏血酸或低pH值或柠檬酸或蛋白酶的作用,可能是多因素综合作用的结果。     

新型凉果褐变抑制剂的研制

为解决广式凉果中二氧化硫超标的问题,本研究以苹果切片和青梅作为模型,进行单一因素和复配试验,通过测定白度、吸光度并结合感官评价,研发出新型的抑制凉果褐变添加剂.结果表明:鲜切苹果片腌制1d的抑制褐变效果最为理想;1.25 mg/gL-半胱氨酸盐酸盐、2 mg/g异抗坏血酸、5 mg/g柠檬酸和0.625 mg/g亚硫酸氢钠对苹果片(腌制1d)褐变均有较好抑制效果;由感官评价可知,L-半胱氨酸盐酸盐的抑制凉果褐变效果强于亚硫酸氢钠;用异抗坏血酸、柠檬酸、L-半胱氨酸盐酸盐进行复配试验,得出最佳配方:1.25 mg/gL半胱氨酸盐酸盐、5mg/g柠檬酸、1mg/g异抗坏血酸.试验表明:L-半胱氨酸盐酸盐及其复配可用于抑制凉果褐变.