Physicochemical properties and application of pullulan edible films and coatings in fruit preservation

The effects of water, sorbitol and a sucrose fatty acid ester (SE) on the water sorption behaviour and thermal and mechanical properties of pullulan‐based edible films as well as the physiological responses of fruit coated with pullulan have been studied. Incorporation of sorbitol or SE in pullulan films resulted in lower equilibrium moisture contents at low to intermediate water activities (a_w), but much higher moisture contents at a_w > 0.75; estimates of monolayer values (within 4.1–5.9 gH₂O kg^?1 solids) were given by application of the Brunauer–Emmett–Teller (BET) and Guggenheim–Anderson–DeBoer (GAB) models. A single glass–rubber transition (T_g), attributed to the polysaccharide component, was detected by calorimetry and dynamic mechanical thermal analysis (DMTA) at a sorbitol level of 15–30% DM. With both tests the strong plasticising action of water and polyol was evident in the thermal curves, and the T_g vs moisture content data were successfully fitted to the Gordon–Taylor empirical model. Multifrequency DMTA measurements provided estimates for the apparent activation energy of the glass transition in the range of ? 300–488 kJ mol^?1. With large‐deformation mechanical testing, large decreases in Young's moduli (tensile and three‐point bend tests) were observed as a result of water‐ and/or polyol‐mediated glass‐to‐rubber transition of the polymeric films. In the moisture content range of 2–8%, increases in flexural modulus (E) and maximum stress (σ_max) with small increases in moisture content were found for films made of pullulan or pullulan mixed with 15% DM sorbitol; a strong softening effect was observed when the water content exceeded this range. Addition of sorbitol increased the water vapour transmission rate of the films, whereas addition of SE had the opposite effect. Application of a pullulan/sorbitol/SE coating on strawberries resulted in large changes in internal fruit atmosphere composition which were beneficial for extending the shelf‐life of this fruit; the coated fruit showed much higher levels of CO₂, a large reduction in internal O₂, better firmness and colour retention and a reduced rate of weight loss. In contrast, similar studies on whole kiwifruits showed increased levels of internal ethylene, which caused acceleration of fruit ripening during storage. © 2001 Society of Chemical Industry     

可食膜的研究进展

可食膜是指由可食性材料形成的膜,主要通过防止气体、水汽和溶质等的迁移来保证食品的质量,延长食品的货架期。可食膜作为一种新型包装材料,具有绿色环保、生物降解、无毒无害、能够提高食品的保质期和提高食品的质量等优点,而且还具有营养价值。因此,近年来国内外对可食膜的研究越来越多,可食膜的应用范围也越来越广。我们日常生活中包装糖果使用的糯米纸、包装冰激凌使用的蛋筒、包装肉菜使用的豆腐皮和包装肉馅使用的肠衣等都是典型的可食性包装。根据可食膜的制备材料不同,本文对多糖类可食膜、蛋白质可食膜、脂质可食膜和复合型可食膜这几种常用的可食膜进行了综述,分别介绍了这几种可食膜的研究状况。并根据近几年来国内外研究进展,对可食膜在果蔬和肉类中的应用进行了叙述。     

Antioxidant Properties of Cocoa Beans (Theobroma cacao L.): Influence of Cultivar and Roasting Conditions

Effects of various roasting conditions on antioxidant properties of five Theobroma cacao L. varieties were investigated. The cocoa beans were roasted at four different temperatures (110–150°C) and three different air humidities (0.3–5.0%). The raw cocoa beans were characterized by high antioxidant activities. The antioxidant properties of the roasted cocoa beans varied markedly among the analyzed cultivars and geographical regions and were affected by roasting conditions. Generally, cocoa beans of the cv. Forastero from Brazil exhibited higher total phenolic content, free radical scavenging activity, and metal chelating ability than samples of the other analyzed cocoa varieties. Roasting at 110°C caused negligible changes in total phenolics content and antioxidant activity of cocoa beans, while almost all samples tended to have lower antioxidant potential when roasting temperature increased. The air humidity used in roasting did not affect the total phenolics content and antioxidant activity for lowest roasting temperature (110°C). Moreover, the obtained results revealed that thermal processing at the higher temperatures and elevated air humidity resulted in the higher antioxidant capacities. It was also found that the ferrous ion chelating activity of cocoa beans increased with the roasting temperature (in the range from 110 to 150°C), with the exception of cv. Trinitario from Papua New Guinea. The data showed that roasting at lower temperatures with humid air are more favorable in terms of preserving the bioactivity of roasted cocoa beans.     

Development of functional pectin edible films with fillers obtained from red cabbage and beetroot

The present study aims to develop through casting, functional composite edible films based on pectin using beetroot powder and red cabbage powder as fillers obtained from by-products of plant tissue industrialisation. Physico-chemical, mechanical, thermal properties and colour stability of the films along 30 days of storage (5–45 °C; absence of light) were evaluated. The moisture and the stress at break decreased, and the intensity of red colour and the hydrophobicity increased with the presence of fillers. According to the FTIR results, there was a good compatibility between matrix and fillers in the composites. Pectin films generated an enhanced stability of red colour after 30 days of storage at 5 and 25 °C and, in general, after 16 days for 45 °C, showing their suitability to be used as colouring agents for edible food packaging applications.     

Clovamide and phenolics from cocoa beans (Theobroma cacao L.) inhibit lipid peroxidation in liposomal systems

Neo-synthesized clovamide and a phenolic cocoa extract (fermented cocoa from Ghana) were evaluated for their capacity to inhibit lipid peroxidation. Their effect was first investigated on phospholipid organic solutions, and then on liposomal systems prepared by high pressure homogenization process. Antioxidants were added to liposomal system following two different protocols (before and after the homogenization treatment) and their protective action was evaluated monitoring the oxidative status of liposomes (exposed to light at room temperature or heated at 40 °C) over three weeks. The results confirmed a significant protective effect of clovamide on liposomal model systems and, in a minor extent, also of cocoa extract. The capacity of phosphatidylcholine liposomes to incorporate clovamide was also evaluated; it was shown that more than 50% of clovamide was englobed in liposomes, although the addition of clovamide solution before the homogenization process led to the isomerization of the molecule from trans to cis form.     

Characterization of the odor-active compounds responsible for atypical aroma notes in cocoa (Theobroma cacao L.)

Cocoa is the key raw material in chocolate manufacturing. The quality of cocoa is crucial for the pleasant aroma of the final confectionery products. Ideally, cocoa shows a rich aroma with floral, sour, malty, earthy, and fruity notes. However, chocolate manufacturing companies occasionally report the presence of off-flavors in fermented cocoa at the level of the incoming goods inspection. Among them, moldy-musty and coconut-like notes are frequently observed. It is hard to establish the presence of off-flavors on the base of sensory data only, as it has mainly been done so far, because this type of assessment is very subjective. Therefore, there is a strong need for an objective method based on analytical data to affirm whether a cocoa batch is suitable or not for further manufacturing. To clarify the molecular background of the moldy-musty and the coconut-like notes, the volatiles were isolated from fermented cocoa samples tainted with off-flavors by solvent extraction and solvent-assisted flavor evaporation (SAFE). The odor-active compounds were determined by comparative aroma extract dilution analyses (cAEDA), using flawless cocoa samples as reference. The first part of the investigation was focused on cocoa samples with a moldy-musty off-flavor. Application of cAEDA revealed (-)-geosmin, 4-methoxy-2,5-dimethylfuran-3(2W)-one, 1W-indole, and 3-methyl-1W-indole as potential off-flavor compounds. This compound selection was based on their odor quality and higher flavor dilution factors in the off-flavor cocoa than in the reference sample. Quantitation of the four compounds in nine off-flavor cocoa samples and calculation of odor activity values (OAVs; ratios of the concentrations to the odor threshold values) suggested crucial roles of (-)- geosmin and 3-methyl-1W-indole for the off-flavor. In the chocolate industry, their quantitation can be used to objectively assess the moldy-musty off-flavor at the level of the incoming goods inspection. Because both compounds are inhomogeneously distributed between testa and embryo, separate quantitation in the two parts of the seeds is required. The second part of the investigation was focused on cocoa samples with a coconut-like note. Application of cAEDA revealed coconut-like smelling compounds δ-octalactone, δ-2-octenolactone, γ- nonalactone, γ-decalactone, δ-decalactone and δ-2-decenolactones as potential causative odorants. Quantitation of these six compounds and calculation of OAVs suggested δ-2-decenolactone as the crucial compound. Chiral analysis showed the presence of pure (R)-δ-2-decenolactone, commonly referred to as massoia lactone. Its key role for the coconut note was finally demonstrated in a spiking experiment: the addition of (R)-δ-2-decenolactone to the reference cocoa in an amount corresponding to the concentration difference between the two samples was able to provoke a coconut note in an intensity comparable to the one in the atypically smelling cocoa. To avoid an undesired coconut note caused by (R)-δ-2-decenolactone in the final products, the chocolate industry may consider its odor threshold value, that is 100 μg/kg, as a potential limit for the acceptance of fermented cocoa in the incoming goods inspection. Caterina's thesis is publication-based and includes the following three papers:     

可食性膜保鲜技术的发展与展望

可食性膜是一种由天然可食性材料制成的选择透过性薄膜,常被应用于保鲜新鲜果蔬,通过控制果蔬的内部气体交换、延缓水分损失、提高机械性能,阻止空气中氧气与食品发生氧化反应,防止微生物细菌的滋生,最终起到降低腐败速率、延长其货架期和提升商品价值的作用。随着这种绿色型保鲜技术的不断发展,可食性膜也被作为抗菌剂、防腐剂、调味剂和增塑剂等功能性成分的载体,由两种或者两种以上材料组成的复合配方涂膜互相丰富并改善了不同类型涂膜之间的保鲜作用,从而得到更加优质有效的可食性涂膜配方。本文主要概述了可食性膜的保鲜原理与成分组成、应用历史及发展演变,综述了可食性膜的类型、特点及其制作工艺,进一步展望了可食性膜的发展方向。     

Variations of peroxidase activity in cocoa (Theobroma cacao L.) beans during their ripening,fermentation and drying

An increase of peroxidase activity in the seeds of cocoa (Theobroma cacao L.) during their ripening has been determined. An additional increase of the peroxidase activity (about 10 times) is observed during the fermentation and drying of the beans. The residual activity determined in the cocoa beans after sun-drying was higher than that in unfermented ripe seeds. The major cocoa isoperoxidase was shown to be an acidic enzyme with pI 4.7. Using isoelectrofocusing, the appearance of two basic isoenzymes of the peroxidase with pI 8.6 and 9.0 during the process of the fermentation has been detected. ©     

可食性果蔬膜包装材料研究进展

目的:为了研究双酶复合酶解大豆分离蛋白制备大豆肽的相对分子量分布及活性片段对实验性高血压大鼠的降压效果。方法:通过单因素实验优选,采取正交实验优化复合酶的酶解工艺,以酶解液对血管紧张素转换酶(ACE)抑制率为指标优选最佳工艺;通过超滤、纳滤后得到最佳分子量片段,应用左硝基精氨酸(L-NNA)诱导大鼠高血压模型,分别给予不同剂量的活性片段进行实验。结果:双酶复合酶解的最佳条件为:在料液比为1:20 g/mL的情况下,酶解温度50℃,酶底比3.0%,酶解pH7.0条件下先用菠萝蛋白酶酶解2 h后,再以酶底比4.0%加入胰蛋白酶,控制温度为40℃、酶解pH为8.0条件下酶解4 h,大豆分离蛋白的水解度35.31%。经过高效液相对酶解液的相对分子量分布得出,大豆分离蛋白原液含有的蛋白质及多肽的相对分子质量主要区间在5000~1.0×10⁵ Da,在双酶复合酶解下,酶解液的蛋白质及多肽的相对分子质量主要区间均在500~4000 Da;通过超滤得出最佳活性片段为1000~3000 Da,药理实验表明,与模型对照组相比各组血压均有降低,且大豆肽剂量组有显著性差异(p<0.05);其中大豆肽高剂量组和卡托普利组相当。结论:双酶复合酶解制备的大豆肽相对分子量较小,活性片段对高血压大鼠模型降压作用显著。     

Characterization of volatile compounds in Criollo,Forastero, and Trinitario cocoa seeds (Theobroma cacao L.) in China

The volatile composition of cocoa from 16 accessions covering three different morphogenetic groups, namely, Criollo, Forastero, and Trinitario, was investigated. Fifty-three compounds were profiled using HS-SPME-GC-MS, and the number of volatiles per accession was found to be significantly associated with the morphogenetic groups. Volatile assemblages differed significantly among Criollo, Forastero, and Trinitario groups (ANOSIM, R = 0.715, p = 0.001). The differences in the volatile compounds of the three morphogenetic groups were essentially quantitative, and only a few compounds were found exclusively specific to a certain group, mainly in Trinitario. Moreover, the volatile compounds differed from these morphogenetic groups, which revealed complex interactions between them, including participation in the same biosynthetic pathways. Principal component analysis revealed that Trinitario cocoa had high contents of furfuryl alcohol, 3-carene, 2-pentanol, 1-pentanol, 2,3-butanediol, 2-heptanol, and benzyl acetate. Criollo cocoa contained high amounts of α-limonene, β-caryophyllene, β-myrcene, α-phellandrene, β-linalool, and acetic acid. Forastero cocoa also exhibited high contents of 3-methylbutanoic acid, 2-(2-butoxyethoxy) ethanol, anethole, and 2,4-pentanediol. However, the volatile compound pattern detected in Forastero cocoa was inconsistent. Volatile profiling of cocoa by HS-SPME-GC-MS and the interrelationship detected among the volatiles can be used as a roadmap for future breeding or biotechnological applications.     

Investigation of chocolate produced from four different Brazilian varieties of cocoa (Theobroma cacao L.) inoculated with Saccharomyces cerevisiae

Properly conducted cocoa fermentation is an important step for the production of high-quality chocolate. The aim of this work was to investigate the effect of four cocoa varieties (CCN51, PS1030, FA13, and CEPEC 2004) inoculated with Saccharomyces cerevisiae CA11 on microbial communities and the profile of volatile compounds and sensory characteristics of chocolate. The S. cerevisiae population increased significantly (p < 0.05) during the fermentations. The microbial communities varied according to cocoa variety fermentation as assessed by denaturing gradient gel electrophoresis (DGGE). The dominant yeasts were S. cerevisiae and Hanseniaspora guilliermondii, while Lactobacillus casei and Gluconobacter oxidans were the predominant bacteria in the four different fermentations analyzed. Sixty-one volatile compounds—including aldehydes (11), ketones (10), esters (14), acids (8), alcohols (8), pyrazines (5), furans (3), and others (caffeine and heptadecane)—were detected and quantified by GC–MS in the different chocolates. The sensory analysis showed that caramel was perceptible in the chocolate of PS1030, while CEPEC2004 was related to astringency, bitterness, and chocolate flavor attributes. The chocolates produced from FA13 and CCN51 were more similar in terms of sour and chocolate aroma. A “temporal dominance of sensation” (TDS) analysis showed that although the bitter attribute was dominant, the fruity, sweet, sour, astringent, and cocoa attributes were also perceptible, depending on the cocoa variety. These results suggest that the cocoa varieties had an influence on the chocolate's quality, which should be considered to obtain chocolate with different sensory characteristics or for better standardization of the process, even when using yeast as a starter culture.     

多糖类可食性食品药物膜的开发与应用

首先介绍了可食性膜的特性要求及特点,然后对多糖类可食性膜的种类和应用进行了综述,最后讨论了其存在的问题及发展趋势。     

Absorption of N-phenylpropenoyl-L-amino acids in healthy humans by oral administration of cocoa (Theobroma cacao)

Besides flavan-3-ols, a family of N-phenylpropenoyl-L-amino acids (NPAs) has been recently identified as polyphenol/amino acid conjugates in the seeds of Theobroma cacao as well as in a variety of herbal drugs. Stimulated by reports on their biological activity, the purpose of this study was to investigate if these amides are absorbed by healthy volunteers after administration of a cocoa drink. For the first time, 12 NPAs were quantified in human urine by means of a stable isotope dilution analysis with LC-MS/MS (MRM) detection. A maximum amount was found in the urine taken 2 h after the cocoa consumption. The highest absolute amount of NPAs excreted with the urine was found for N-[4'-hydroxy-(E)-cinnamoyl]-L-aspartic acid (5), but the highest recovery rate (57.3 and 22.8%), that means the percentage amount of ingested amides excreted with the urine, were determined for N-[4'-hydroxy-(E)-cinnamoyl]-L-glutamic acid (6) and N-[4'-hydroxy-3'-methoxy-(E)-cinnamoyl]-L-tyrosine (13). In order to gain first insights into the NPA metabolism in vivo, urine samples were analyzed by LC-MS/MS before and after beta-glucuronidase/sulfatase treatment. As independent of the enzyme treatment the same NPA amounts were found in urine, there is strong evidence that these amides are metabolized neither via their O-glucuronides nor their O-sulfates. In order to screen for caffeic acid O-glucuronides as potential NPA metabolites, urine samples were screened by means of LC-MS/MS for caffeic acid 3-O-beta-D-glucuronide and 4-O-beta-D-glucuronide. But not even trace amounts of one of these glucuronides were detectable, thus excluding them as major NPA metabolites and underlining the importance of future investigations on a potential O-methylation or reduction of the N-phenylpropenoyl moiety in NPAs.     

Milk proteins for edible films and coatings

Due to the recent increase in ecological consciousness, research has turned toward finding edible materials. Viable edible films and coatings have been produced using milk proteins. These films and coatings may retard moisture loss, are good oxygen barriers, show good tensile strength and moderate elongation, are flexible, and generally have no flavor or taste. Incorporation of lipids in protein films, either in an emulsion or as a coating, improve their properties as barriers to moisture vapor. Interactions between chemical, structural properties, as well as film-forming conditions and functional properties of edible milk films are elucidated. Some potential uses of milk protein packaging, which are hinged on film properties, are described with examples.     

Extraction and characterization of pectin from cacao pod husks (Theobroma cacao L.) with citric acid

Variables that influence the citric-acid extraction of pectins from cacao pod husk were examined. A screening study tested the main parameters influencing pectin yield and uronic acid content by a factorial fractional 3^3?1 design. Further, response surface methodology was applied using a central composite design to examine the effect of a greater region of variable values on pectin yield and uronic acid content. The yield was optimized by increasing the temperature and time. None of the variables had a significant effect on the uronic acid content, and there was lack of fit of the model to the uronic acid content. From the fitted model, extraction conditions with aqueous citric acid at pH 3.0 for 95 min at 95 °C provided a predicted yield of approximately 9.0 g/100 g dry cacao pod husks. The obtained experimental value for the yield was 10.1 ± 0.3 g/100 g dry cacao pod husks, with the pectins containing 65.1 ± 0.8 g uronic acid/100 g fraction, DE 40.3% and DA 15.9%. At 5 g/100 g aqueous solution, the fraction behaved as a concentrated solution and presented a non-Newtonian shear-thinning behavior, well described by Cross Model. Additionally, the fraction formed gels at acidic pH and high sucrose content.     

Structural and chemical changes in cocoa (Theobroma cacao L) during fermentation,drying and roasting

Cocoa seeds and pulp were fermented for 144 h, followed by natural drying. The tegument was removed and the cotyledons were broken into nibs which were roasted at 150 °C for 30 min. Non‐fermented material, material fermented for 24, 48 and 72 h, material fermented for 144 h and then dried, and also the roasted nibs, were all prepared for chemical and microscopic analyses. Light microscopy revealed the presence of anionic and cationic residues and of neutral sugars. During fermentation there was a reduction in the cytoplasmic content of phenolic compounds and in the number of protein bodies. The cell wall showed a reduction in anionic residues and a loss of crystallinity. These alterations were maximum after 72 h. Drying and roasting increased the number of damaged cells and reduced the amount of cytoplasmic material. The chemical analyses generally confirmed the microscopy results. The concentration of amino‐terminal groups and total free amino acids increased during fermentation (up to 72 h), but returned to the initial values after roasting. The principal chemical changes were related to reducing sugars, free amino acids, proteins and phenols, and PCA was suggested as a useful tool to compare different samples. Microscopic analysis revealed the degradation of protein and phenolic bodies and cellular damage during roasting. © 2000 Society of Chemical Industry