不同包装结合低温贮藏对‘保研-7号’红毛丹品质的影响

比较三种包装对红毛丹(Nephelium lappaceum L.)果实在低温贮藏下品质的影响,获得实用的绿色保鲜技术。以海南红毛丹‘保研-7号’为材料,在(6±1) ℃下,以不包装作为对照CK,研究聚乙烯袋(PE)、硅窗袋(SW)、复命袋(FM)3种包装及CK对红毛丹果实贮藏品质的影响。结果显示贮藏16 d,PE、SW、FM包装及CK果实褐变指数分别为0.67、0.62、0.64和0.92,好果率分别为45.56%、53.33%、65.56%和5.56%;PE、SW、FM包装的果肉可溶性固形物分别为17.60%、18.47%、19.80%均高于CK 16.70%,可滴定酸分别为0.47%、0.56%、0.60%也高于CK 0.40%,可溶性蛋白分别为29.29、29.53、31.92 mg·100 g-1高于CK 27.75 mg·100 g-1;PE、SW、FM包装的红毛丹果皮相对电导率和丙二醛增长速率小于CK,FM包装的果皮相对电导率40.88%和丙二醛10.21 mmol·g-1·FW为最低;贮藏后期红毛丹果皮总酚含量均减少,PE、SW、FM包装的红毛丹总酚7.82、8.81、9.87 OD₂₈₀·g-1均高于CK 6.22 OD₂₈₀·g-1;果皮花青素在贮藏期间也不断下降,FM包装红毛丹果皮花青素下降速率最慢,贮藏后花青素含量0.75 U·g-1为最高;贮藏第16 d,PE、SW、FM包装的红毛丹多酚氧化酶活性(354、313、290 U·g-1)均小于CK(367 U·g-1),过氧化物酶活性(13.22、13.78、12.19 U·g-1)同样也小于CK(21.19 U·g-1)。与CK相比,3种包装均能有效抑制红毛丹品质劣变并保持其新鲜品质,FM包装红毛丹果肉和果皮在低温贮藏中11个指标变化均最小,保持新鲜品质最好,是3种包装中保持品质最佳的包装,可为红毛丹采后包装技术的应用提供技术支撑。     

不同的亲水胶体对银杏浊汁稳定性的影响

将不同的亲水胶体添加于银杏浊汁中,结果发现高酯果胶、瓜儿豆胶和亚麻籽胶对银杏浊汁的稳定效果较好。对分别加入这3种胶体的银杏浊汁进行储藏稳定性研究,结果表明:0.05%(w/v)的亚麻籽胶对银杏浊汁在储藏期间保持混浊稳定性的效果最好。银杏浊汁的混浊稳定性要依靠悬浮颗粒间的静电排斥作用,更主要的是依靠亲水胶体增稠所提高的大分子空间排斥作用。     

New beverages of lemon juice with elderberry and grape concentrates as a source of bioactive compounds

Considering the health potential of lemon and berry fruits, different functional beverages rich in antioxidant phytochemicals, which demonstrated beneficial effects, were developed. To fulfill this objective, lemon juice was combined with 2 different concentrates, elderberry and grape, in a proportion of 5% (w/v). Bioactive composition (flavonoids and vitamin C) and color stability, as well as the antioxidant capacity of mixtures, during a period of 56 d of storage, were studied. A protective role of anthocyanins on ascorbic acid preservation was noted for both lemon-berry blends, keeping vitamin C stable until the end of the storage. In addition, the new drink combining lemon and elderberry performed better than the grape-lemon mixture in terms of health-promoting phytochemicals content, just as in vitro antioxidant capacity and color characteristics. PRACTICAL APPLICATION: Beverages made from lemon juice and berries could contribute to develop new drinks with a prolonged preservation of bioactive compounds throughout storage, keeping an attractive color and a high antioxidant activity during long periods of time. The information obtained in the present work is in agreement to the rules of health and safety for juices established by the Directive of European Commission Dir2001/112/CE incorporated to the Spanish law through the RD1050/2003 regulation. Consequently, an improved performance of industrial products would be achieved.     

Preparation and Partial Characterization of Eggshell Calcium Chloride

To minimize eggshell waste, calcium in eggshells was extracted as calcium chloride using 4% (w/v) HCl solution for an extraction period of 3 hs with the ratio of eggshell to HCl being 1:15 (w/v). After hydrolysis, the residues were removed by centrifugation at 1774 × g for 10 min, and the solution was heated to 110–115°C until dried, this gave an eggshell calcium chloride at a yield of 87.38% (w/w). The calcium chloride powder in this study was composed of 0.3% protein and 94.37% ash, with pH 5.27 and showed high solubility. It contained minute amount of heavy metal constituents within the specification of the Thai Food Act. X-ray diffraction analysis indicated that eggshell calcium chloride powder thus prepared was composed mainly of CaCl₂.2H₂O. The eggshell CaCl₂ was also tested for its functional property as a firming agent in canned rambutan. The results showed that both eggshell and commercial calcium chloride gave a firm texture to canned rambutan, therefore eggshell CaCl₂ can be prepared and used as food processing aids.     

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.     

Nonenzymatic Browning in Aseptically Packaged Orange Juice and Orange Drinks. Effect of Amino Acids, Deaeration, and Anaerobic Storage

Single strength orange juice and synthetic orange drinks containing 10% (v/v) orange juice and 0.4 and 0.8% w/w concentrations of each amino acid, aspartic acid, arginine, and 4-aminobutyric acid were aseptically packaged using 250 mL Tetra Brik Packs. Samples were stored at 24°C for 16 wk under anaerobic and aerobic conditions, and were tested every 4 wk for nonenzymatic browning, ascorbic acid (AA) retention, dehydroascorbic acid (DHAA) formation, and sensory changes. Deaeration and anaerobic storage resulted in increased retention of ascorbic acid. However, there was very little change in the flavor score, browning, color or change in the amino acid content of the different samples during the entire storage period.     

Use of ultrafiltration for preparing improved tomato pulp

The characteristics of high-quality tomato pulp (commercial def.: crushed or diced tomatoes with about 30% tomato juice as packing medium) canned with tomato juice pulp enriched by ultrafiltration as packing medium were compared with those covered with conventional vacuum-concentrated juice.
Both hot- and cold-break products were prepared and those containing 20% serum-reduced packing juice proved to be the best, showing no signs of syneresis on storage and with improvements in sensory properties, colour and non-enzymatic browning; some volatile components were reduced.     

Stability and Rheological Properties of Egg Yolk Granule Stabilized Emulsions with Pectin and Guar Gum

The effects of pectin and guar gum on rheology, microstructure and creaming stability of 1% (w/v) egg yolk granule stabilized emulsions were investigated. While the addition of low amount of pectin (0.1% (w/v)) had no effect on the emulsion viscosity, the addition of 0.5% (w/v) pectin greatly increased the viscosity. Granule-stabilized emulsion without hydrocolloids reflects the pseudoplastic behavior (shear-thinning behavior with flow behavior index, n < 1.0). Hydrocolloids, especially at high concentrations, affected the viscoelastic behavior of the emulsions and both storage (G′) and loss modulus (G′′) were regarded as frequency dependent. Emulsions behaved like a liquid with G′′ > G′ at lower frequencies, and like an elastic solid with G′ > G′′ at higher frequencies. Emulsion microstructure indicated that the presence of hydrocolloids induced flocculation. Creaming stability of emulsions was enhanced by the presence of hydrocolloids and increasing hydrocolloid concentration decreased the creaming by restricting the movement of oil droplets.     

蒲公英内生真菌PG23产抗菌物质发酵培养基的优化

为了提高蒲公英内生真菌产抗菌活性物质的能力,对其液体发酵培养基的组成进行优化.以大肠杆菌为指示菌,采用单因素分析法考察最佳的碳源、氮源组成,以添加蒲公英汁模拟宿主内环境提高产抗菌物质的能力;采用Box-Behnken设计和响应面分析法对培养基组成进行优化.结果表明,PG23产抗大肠杆菌活性物质的最适培养基组成为在马铃薯浸出液的基础上,添加葡萄糖2.5％(w/v)+豆油0.5％ (w/v)为碳源,添加玉米粉0.1 5％ (w/v)为氮源,添加8％ (v/v)蒲公英浸汁模拟体内环境.优化后的蒲公英内生真菌PG23的发酵液提高了产抗大肠杆菌的能力,对大肠杆菌的抑菌直径达到了26.7mm,与优化前相比提高了29％.同时发现,蒲公英内生真菌能单独利用豆油作为碳源促进抗菌活性物质的产生.     

Effect of concentrated plum juice on physicochemical and sensory properties of yoghurt made at bench top scale

Yoghurt with 9% (v/v) of plum juice concentrate (PJC) was stored for 24 days in darkness at 6 °C. Titratable acidity and pH were similar in all samples during storage. The firmness was in the range of 1.7–2.3 N and correlated with total solids of the mixes (R² = 0.982). The sample with PJC and 5.33% (w/v) nonfat dry milk had the highest firmness and the weakest creaminess. The colour in PJC yoghurt was stable during the first seven days of storage. In the ranking test for acceptability, there were no significant differences (P ≤ 0.05) between the yoghurts.     

Decontamination with lactic acid/sodium lactate buffer in combination with modified atmosphere packaging effects on the shelf life of fresh poultry.

The effect of the treatment with various concentrations (2%, 5%, 7.5% and 10% w/v) of lactic acid/sodium lactate buffer (pH 3.0) combined with modified atmosphere packaging (MAP) (90% CO2/10% O2) on the shelf life and organoleptic quality of fresh chicken legs stored at 6 degrees C was investigated. The CO2 concentration of all samples packed in modified atmosphere (MA) decreased during the first 3 days of storage, followed by a gradual increase after the third day, while O2 showed a corresponding decrease. The buffering capacity of the buffer systems seem to be sufficient to maintain a low pH of the skin during storage. Legs treated with 2, 5, 7.5, and 10% (w/v) lactic acid/sodium lactate buffer (pH 3.0) combined with MAP have a shelf life at 6 degrees C of 14, 15, 16 and 17 days, respectively. The shelf life when the product was not treated with lactic acid was 1, 2.3 and 4 days shorter, respectively.     

青梅甘蔗复合发酵酒加工工艺

以梅浆:甘蔗汁=1∶1的混合浆为原料,研究了青梅甘蔗复合发酵酒(简称为梅酒)的关键加工工艺,具体包括:梅浆酶解条件、梅酒发酵工艺、梅酒澄清条件。结果表明,酶解的适宜条件为:酶解浓度251.5 mg/L,温度45℃,时间4 h;发酵条件为:菌种接种量5%,SO2添加量100 mg/L,初始pH3.2,发酵温度28℃;在明胶、皂土、壳聚糖3种澄清剂中,以皂土的澄清效果最佳,其最佳澄清条件为:添加量0.08 g/100 mL、温度25℃、处理10 h。     

Effect of macerate enzymes on the yield,quality, volatile compounds and rheological property of prickly pear juice

Pectinase and cellulase enzymes were used to investigate efficacy for improving juice yield, stability and quality from prickly pear fruit. Pectinase improved the yield, stable color, color-assayed as release of anthocyanins or carotinoids and clarity of the juice. A significant increase in the effectiveness of pectinase was observed as the concentration was increased from 0.05 to 0.50% v/w. However, at concentration > 0.25% v/w they tended to impart a bitter flavor in the juice. Among three concentrations of pectinase and cellulase, pectinase at 0.50% v/w produced higher yield, a sediment-free clear juice and high-quality juice. The results indicated that depectinated clarified prickly pear juice behaves as a Newtonian fluid. It was found that the activation energy (Ea) for viscous flow was in the range of 5.02 x 10(3)-20.06 x 10(3) kJ/mol depending on the concentrations of pectinase and cellulase enzyme treatment of prickly pear juice, in contrast to 22.15 x 10(3) kJ/mol in untreated juice. Volatile compound concentrations of twelve compounds were not affected by pectinase and cellulase treatment. Overall the quality of prickly pear juice was better in pectinase-treated juice compared with untreated and cellulase-treated juice.     

Effect of ascorbic acid on the odours of cloudy apple juice

Ascorbic acid is used in apple juice as an antibrowning agent. This study investigated the effect of ascorbic acid (0.0–0.2% w/v) on the odours of cloudy apple juice using sensory evaluation and gas chromatography (GC). The increase in ascorbic acid concentration in the apple juice resulted in increases in green and unnatural odours and decreases in fresh, fruity and apple-like odours. In the GC determination, 23 volatile compounds were detected in apple juice. Aroma value, which showed the relative importance of volatile compounds, was used to elucidate the changes in odours of apple juice due to the addition of ascorbic acid. The aroma values of hexanal and trans-2-hexenal in the apple juice with 0.2% w/v ascorbic acid increased about 4 and 5-fold from those in the ascorbic acid-free apple juice, respectively. On the other hand, the aroma values of esters insignificantly changed in the apple juice with ascorbic acid. The increases in aroma values of aldehydes corresponded well with the increase in green odour in the apple juice with ascorbic acid.     

Two Endogenous Substrates for Polyphenoloxidase in Pericarp Tissues of Postharvest Rambutan Fruit

Abstract: The catalytic oxidation of phenolic substrates by polyphenoloxidase (PPO) causes pericarp browning of postharvest rambutan fruit. In the present study, PPO and its endogenous substrates were extracted from rambutan pericarp tissues (RPT). The substrate extracts were sequentially partitioned with ethyl acetate and n-butanol. The analysis of total phenolic content showed that the most phenolic compounds were distributed in ethyl acetate fraction. By high-performance liquid chromatography (HPLC), (−)-epicatechin (EC) and proanthocyanidin A2 (PA2) were identified from this fraction. After reacting with rambutan PPO, EC turned brown rapidly within 10 min, indicating that it was a significant endogenous substrate. Although PA2 could also be oxidized by the PPO, it turned brown very slowly. In addition, because EC and PA2 were continually catalyzed into browning products by PPO during storage of the fruit at 4 and 25 °C, their contents in RPT gradually declined with the extended storage time. It was further observed that both substrate contents in rambutan fruit storing at 25 °C decreased more rapidly than that storing at 4 °C, suggesting that low temperature inhibited the catalytic oxidation of substrates so as to slow down pericarp browning. Practical Application: Pericarp browning is a serious problem to storage and transport of harvested rambutan fruit. A generally accepted opinion on the browning mechanism is the oxidation of phenolic substrates by PPO. Ascertaining PPO substrates will effectively help us to control enzymatic reaction by chemical methods so as to delay or even prevent pericarp browning of harvested rambutan fruit.     

DEVELOPMENT OF A SWEETENER FROM BLACK PLUM (VITEX DONIANA) FRUIT

The Black plum (Vitex doniana) fruit was studied in respect of the chemical composition of its edible pulp, and syrup produced by concentration of extracted juice. Organoleptic evaluation was also conducted on the developed syrup. The results show that the edible pulp of the fruit is acidic (PH 5.20), high in moisture (67.9%), sucrose (12.5%) and reducing sugar (7.3%), and fairly rich in vitamin C (28.5 mg/100 g). Temperature of water used for extracting juice from the pulp correlated positively with soluble solids (r=0.86), titratable acidity (r=0.91) and negatively with vitamin C (r=?0.61). The syrup contained higher reducing sugars (51.7%), lower moisture (25.0%), but similar sucrose (12.9%) content compared to the pulp. The soluble solids of the extracted juice and consequently the yield of the syrup varied with water temperature. An optimum temperature of 80°C gave 20% (w/w) syrup per pulp. The syrup compares favorably with sucrose in sensory properties in model foods.     

Effect of fusel oil addition on volatile compounds in papaya wine fermented with Williopsis saturnus var. mrakii NCYC 2251

The impact of fusel oil addition on volatile compounds formation in papaya wine fermented with yeast Williopsis saturnus var. mrakii NCYC2251 was studied with a view to enhancing papaya wine aroma production. Time-course papaya juice fermentations were carried out using W. saturnus var. mrakii NCYC2251 with fusel oil added (0, 0.1 and 0.5% v/v). Fermentation characteristics in terms of yeast growth, Brix and pH changes were similar for all fermentations except for those added with 0.5% (v/v) fusel oil. The addition of 0.5% (v/v) fusel oil inhibited yeast growth. A wide range of volatile compounds were produced during fermentation including acids, alcohols, esters and aldehydes with esters being the most abundant volatile compounds produced. The addition of 0.1% (v/v) fusel oil reduced the production of undesirable volatiles such as ethyl acetate and acetic acid, while increasing the desirable volatiles production such as ethanol and acetate esters. This study suggests that papaya juice fermentation with W. saturnus var mrakii NCYC 2251 together with a low concentration of added fusel oil can be another means of modulating papaya wine aroma compound formation.     

A study of the production of clarified banana juice using pectinolytic enzymes

Pectinolytic enzyme treatments to increase the yield, reduce the viscosity and clarify the juice obtained from ripe banana pulp were studied. Six commercial enzyme preparations were tested on pulps of different ripenesses. Optimal conditions with respect to enzyme concentration, incubation temperature, time and pH levels are reported for the two most effective enzyme preparations. Clear juice yields of between 55 and 60% (based on pulp weight used) are obtained from pulp incubated at 45°C for 1 hr with 0.01% w/w of enzyme by subsequent centrifugation at 2900 maximal relative centrifugal force for 20 min. This corresponds to a yield of total and reducing sugars present in the pulp of over 75%. Untreated control pulps yield less than 5% of juice under these conditions. Hydraulic pressing of the pulps at 16 kg/cm² gives similar juice yields to those obtained by centrifugation. The juice has an excellent flavour and aroma and provides a possible use for the large quantities of reject bananas available in producer countries.     

Development and characterization of an edible chitosan–whey protein nano composite film for chestnut (Castanea mollissima Bl.) preservation

Chitosan (CHI) and whey protein are usually used to prepare edible films for food preservation. However, the composite film composed of the two components does not yield satisfactory properties for chestnut preservation. In this study, nano-cellulose and cinnamaldehyde (CMA) were added to CHI and whey protein, creating a new composite film with strong water retention, bacteriostatic, and mechanical properties. The water vapor permeability (WVP) of the film decreased by 21.61% with the addition of 0.5% (w/v) nano-cellulose, and 23.02% with the addition of 0.3% (w/v) CMA. Furthermore, water solubility (WS) decreased 22.05%, and the density of the film was significantly improved with the addition of 0.3% (w/v) CMA. The optimized formula of the film was CHI 2.5% (w/v), whey protein 3.0% (w/v), nano-cellulose 0.5% (w/v), CMA 0.3% (w/v), and pH 3.8, as determined by orthogonal testing L9(3⁴), with fuzzy comprehensive assessment, of WVP, WS, tensile strength, and elongation at break. The film clearly inhibited the growth of E. coli, S. aureus, and Chinese chestnut fungus, destroying the mycelial structure of the fungus. In addition, coating effectively reduced the weight loss, mildew rate, and calcification index during 16 days of storage of chestnuts at 25 °C.     

冷破碎红富士苹果浆发酵低度苹果酒工艺优化

以冷破碎红富士苹果浆为原料发酵制备低度苹果酒,通过分析不同酵母发酵周期的糖度、酒精度、pH和总酸筛选酵母菌株;在此基础上采用单因素与响应面试验以优化发酵工艺,确定冷破碎苹果浆发酵酒的最佳条件,通过分析酒品指标,与苹果清汁发酵酒的品质进行对比。结果表明,冷破碎苹果浆发酵酒的最佳工艺参数为:SY酵母发酵的初始糖度18%、酵母接种量0.1 g/L、发酵温度20℃;苹果浆发酵酒的残糖（7.5±0.46 g/L）、酒精度（7.8±0.1%）分别与苹果清汁发酵酒的残糖（7.3±0.31 g/L）、酒精度（8.0%±0.1%）差异不显著;苹果浆发酵酒的总酚（74.99±1.23 mg/100 mL）和有机酸（5.33±0.01 g/L）等成分含量高于苹果汁发酵酒（总酚47.5±2.2 mg/100 mL,有机酸5.01±0.03 g/L）。该结果可供苹果酒实际生产借鉴,也为苹果加工产业多元化发展提供思路。