Heat resistance of ascospores of Byssochlamys nivea in milk and cream

Byssochlamys nivea strains of rather varying origin used for heat inactivation experiments were cultured for 28 days at 30 degrees C on malt extract agar, since under these conditions the highest degree of heat resistance of the ascospores was observed. Inactivation was performed in steel capillary tubes to obtain reproducible results under experimental conditions comparable to those prevailing in practice. An inactivation temperature of 92 degrees C proved to be most practical. Decimal reduction times for the individual strains at this temperature in Ringer's solution varied between 1.3 and 2.4 s. In the temperature range studied, inactivation of ascospores in UHT milk (1.5% w/w fat content) and cream (10% w/w fat content) has not been found to differ significantly from that in Ringer's solution. Homogenization of milk as applied in practice did not affect heat inactivation of ascospores. Assuming the most unfavorable conditions (50 ascospores/l and using the most heat-resistant strain) the following relations between the level of infected 500 g packages were calculated: 1 of 10(6) packs infected; 24 s at 92 degrees C; 1 of 10(3) packs infected; 16.5 s at 92 degrees C; 1 of 10(2) packs infected, 14 s at 92 degrees C.     

Heat resistance of Byssochlamys nivea, Byssochlamys fulva and Neosartorya fischeri isolated from canned tomato paste

Cultures of heat resistant molds (20) were isolated from spoiled canned tomato paste in order to estimate the pasteurization efficiency applied to commercially canned products. Ascospores of nine strains grown on malt extract agar for 30 days at 30°C, survived heating at 85°C for 20 min when initial numbers were near 10⁵/mL. Of these heat resistant strains were identified: two Byssochlamys nivea, three Byssochlamys fulva and four Neosartorya fischeri strains. Ascospores of all cultures were more heat resistant in tomato juice than in phosphate buffer. Thermal death rate curves were nonlogarithmic but approached logarithmic death rates at higher temperatures. The thermal destruction time for 1 log₁₀ at 90°C was 1.5 min for a Byssochlamys nivea strain, 8.1 min for a Byssochlamys fulva strain and 4.4 to 6.6 min for Neosartorya fischeri strains.     

The effect of intermittent shaking, headspace and temperature on the growth of Alicyclobacillus acidoterrestris in stored apple juice

The presence of Alicyclobacillus acidoterrestris in stored juices can be difficult to detect. In this study the effects of storage temperature, headspace and agitation of juice containers was investigated. The results indicate that the amount of headspace has a significant effect on growth of vegetative cells and spores of A. acidoterrestris at 35 °C. Intermittent shaking before sampling increased growth and therefore probable detection rates at 30 °C, Agitating containers and sampling from several areas within containers is therefore recommended for determining whether A. acidoterrestris is present or absent from stored juice, especially in large containers.     

The effect of temperature on microbial growth in apple cubes packed in film and preserved by use of orange juice

Red delicious apple cubes were packed in fresh orange juice containing chemical preservatives (citric and ascorbic acid, potassium sorbate) and covered with plastic films of different gas permeabilities (polyethylene and EVA‐SARAN‐EVA) before storage at 4, 10 and 20 °C. The concentration of potassium sorbate in the product was optimized with respect to colour and microbial growth. Yeast and mould growth was modelled by Gompertz and linear equations to derive parameters such as lag phase, maximum microbial population and specific microbial growth or rates of decline. Activation energies for the specific growth rates were estimated from Arrhenius‐type equations and the time required to reach microbial counts of 10^6±0.2 CFU g^?1 was determined in all cases. At 4 °C, these values were longer than 25 days in all systems tested. The use of a low gas permeability film and an adequate potassium sorbate concentration extended storage life at higher temperatures.     

The effect of the manufacturing method on the characteristics of apple juice

Summary Apple juices, obtained by straight pressing, pulp enzyming or liquefaction and clarification by the conventional process using bentonite, gelatin, and silicasol or by ultrafiltration, were analysed for sugar and acid content, colour, polyphenol content, ultrafiltration fluxes and polysaccharide content and composition. The amount and composition of the high-M _r polysaccharide fractions found indicate the importance of the juice processing method and enzyme preparation chosen. Polysaccharides solubilized from the cell walls were found to contain galacturonic acid and arabinose as the major constituent sugars. Ultrafiltration enabled the removal of high-M _R polymers but neutral arabinans were still found to be present in ultrafiltered juice.

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Der Einfluß der Herstellungsmethode auf Merkmale des Apfelsaftes

Zusammenfassung In verschiedenen Apfelsäften, die durch direkte Pressung, enzymatische Pulpbehandlung oder Verflüssigung und auf konventionelle Weise mittels Bentonit, Gelatine und Silicasol oder durch Ultrafiltration geklärt wurden, wurden der Zucker- und Säuregehalt, die Farbe, der Polyphenolgehalt, die Ultrafiltrations-Durchflußgeschwindigkeit und der Gehalt und die Zusammensetzung der Polysaccharide bestimmt. Die Menge und Zusammensetzung der gefundenen hochmolekularen Polysaccharid-Fraktionen zeigen deutlich die Bedeutung der Herstellungsmethode und der verwendeten Enzympräparate. Galakturonsäure und Arabinose waren die Hauptbestandteile der aus den Zellwänden gelösten Polysaccharide. Die Ultrafiltration ermöglichte die Abtrennung von hochmolekularen Polymeren; jedoch wurden auch in ultrafiltrierten Säften noch neutrale Arabinane nachgewiesen.

     

均质工艺对苹果浊汁品质的影响

利用不同均质压力(0、10、20、30和40MPa)、均质次数对苹果浊汁进行均质,研究均质工艺对苹果浊汁的褐变情况、悬浮稳定性的影响,还对果汁中果肉颗粒的大小、果汁粘度这两个影响果汁悬浮稳定性的因素进行了探讨。实验结果表明,在30MPa下均质一次可以得到最理想的苹果浊汁。     

Antibacterial activity and mechanism of cinnamic acid and chlorogenic acid against Alicyclobacillus acidoterrestris vegetative cells in apple juice

The aim of this study was to investigate the antibacterial activity and mechanism of cinnamic acid and chlorogenic acid against Alicyclobacillus acidoterrestris. Minimum inhibitory concentrations of cinnamic acid and chlorogenic acid were 0.375 and 2.0 mg mL⁻¹, and the minimum bactericidal concentrations were 0.50 and 4.0 mg mL⁻¹, respectively. The apple juice ingredients had little influence on the inactivation of A. acidoterrestris. After treatment with cinnamic acid and chlorogenic acid, the morphology of A. acidoterrestris cells were severely destroyed; the leakage of nucleic acids and proteins increased significantly. SDS-PAGE investigation of bacterial proteins proved that the loss of soluble proteins was obvious as well. These results demonstrated that cinnamic acid and chlorogenic acid exerted their antibacterial activity mainly by an action mode of membrane disruption. This study provides an alternative method for the control of A. acidoterrestris-related spoilage in the fruit juice/beverage industry.     

Bicarbonate inhibition of Saccharomyces cerevisiae and Hansenula wingei growth in apple juice

The ability of sodium bicarbonate to inhibit growth of Saccharomyces cerevisiae and Hansenula wingei in apple juice was investigated. Sodium bicarbonate at concentrations of 0.06, 0.12, and 0.24 M was added to pasteurized apple juice that was then inoculated with 10(3) or 10(5) cfu/ml of either yeast. Growth of both yeasts was inhibited by 0.12 M sodium bicarbonate when incubation was at 4 degrees C; 0.24 M sodium bicarbonate caused a slow die off of yeast. At 18 degrees C, H. wingei became more sensitive and died in the presence of 0.12 M sodium bicarbonate, but S. cerevisiae became resistant to 0.24 M sodium bicarbonate. These results could not be attributed to bicarbonate-induced pH elevation or sodium. Potassium and ammonium bicarbonate were also inhibitory, implicating bicarbonate ion as the antimicrobial agent.     

酶法生产草莓汁的研究

研究了直接榨汁、解冻后榨汁、纤维素酶酶解、果胶酶酶解四种方法对生产草莓汁品质的影响,结果表明,果胶酶酶解生产草莓汁效果最佳。通过正交实验研究了酶加入量、酶解温度、酶解时间对草莓汁出汁率、花色苷及Vc的影响。结果表明,果胶酶制取草莓汁的最佳工艺是:酶加入量0.005%、酶解时间1h、酶解温度50℃。此条件下生产的草莓汁色泽鲜艳、营养丰富,而且美味可口。      

Inhibitors of the epidermal growth factor receptor in apple juice extract

The polyphenol-rich extract of a consumer-relevant apple juice blend was found to potently inhibit the growth of the human colon cancer cell line HT29 in vitro. The epidermal growth factor receptor (EGFR) and its subsequent signaling cascade play an important role in the regulation of cell proliferation in HT29 cells. The protein tyrosine kinase activity of an EGFR preparation was effectively inhibited by the polyphenol-rich apple juice extract. Treatment of intact cells with this extract resulted in the suppression of the subsequent mitogen-activated protein kinase cascade. Amongst the so far identified apple juice constituents, the proanthocyanidins B1 and B2 as well as quercetin-3-glc (isoquercitrin) and quercetin-3-gal (hyperoside) were found to possess substantial EGFR-inhibitory properties. However, as to be expected from the final concentration of these potential EGFR inhibitors in the original polyphenol-rich extract, a synthetic mixture of the apple juice constituents identified and available so far, including both proanthocyanidins and the quercetin glycosides, showed only marginal inhibitory effects on the EGFR. These results permit the assumption that yet unknown constituents contribute substantially to the potent EGFR-inhibitory properties of polyphenol-rich apple juice extract. In summary, the polyphenol composition of apple juice possesses promising growth-inhibitory properties, affecting proliferation-associated signaling cascades in colon tumor cells.     

温度对苹果汁中扩展青霉生长和产毒的影响

在苹果汁培养基静置培养条件下,研究了培养温度为28、25、20、16、12、4℃时扩展青霉的生长和产毒情况。结果表明,在各贮藏温度下,扩展青霉均可在苹果汁中生长,并产生大量毒素。温度越高,生长速率和产毒速率越快,但生长高峰期和产毒高峰期发生的先后顺序差别很大。其中25℃是扩展青霉的最适生长和产毒温度,最大生物量和产毒量分别达到4.35 g/L和570.53 mg/L,在冷藏温度4℃时菌体仍能生长和产毒。因此在苹果汁的生产和贮藏过程中要充分考虑温度的影响,以减少果汁中展青霉素污染的风险。     

Detection of fruit juice adulteration in apple and pear juice

A method has been developed to detect the adulteration of pear juice with apples and apple juice with pears. In different varieties of apples and pears and in several commercial juices the flavonoids were examined by HPLC with respect to their quality and quantity. The chalcones phloretin glucoside and phloretin xyloglucoside are typical compounds found in apples (detection limit 7 ng). They are suitable indicators for detecting adulteration of pear juice with apples. Isohamnetin glucoside cannot be detected in apples (detection limit 10 ng), but can be used to detect pears in apple juice. The extract or juice was purified with the aid of a polyamide column. The evaporated eluate of methanol was analysed by HPLC (gradient: acetonitrile/1% acetic acid). An RP-18 column and a UV-detector were used. Additionally, the UV spectra of the compounds indicating an adulteration were recorded by a diode array detector.     

苹果汁中耐热菌培养基的优化及生长曲线

通过对苹果汁中分离耐热菌和德国标准耐热菌菌株基础培养基的正交优化,确定最佳的培养基。得出最佳培养基配比是(质量分数):德国标准菌:蛋白胨0.5%,果糖0.2%,酵母粉0.2%,MgSO4·2H2O0.1%,CaCl20.5%,KH2PO40.12%,MnSO4·4H2O0.05%;分离菌:蛋白胨0.5%,葡萄糖0.2%,酵母粉0.2%,MgSO4·2H2O0.1%,CaCl20.5%,KH2PO40.12%,MnSO4·4H2O0.05%。并计算得出吸光度与细菌浓度之间的关系公式及用优化培养基培养绘制耐热菌生长曲线。     

草莓清汁生产技术的研究

以草莓鲜果为原料，运用多种制汁和澄清方法进行试验，选出了较为经济、快速、实用的制汁技术和澄清技术，本文同时提出了生产草莓清汁的最佳工艺要点。     

Antioxidant activity of commercial ready-to-drink orange juice and nectar

Total antioxidant activity (TAA), total phenolic compounds (TPC), and physicochemical characteristics of ready-to-drink orange juice and nectar from the most consumed brands available in Brazil were evaluated. TPC ranged from 18.7 to 54.2 mg of gallic acid/100 mL, and TAA varied from 57.88 to 349.32 μmol TEAC/100 mL ready-to-drink orange juice and nectar. The ascorbic acid content was the only physicochemical parameter that showed strong variation among packages and brands. Correlation of TPC with TAA showed that the higher the level of TPC the higher the TAA. Correlation of ascorbic acid content with TAA is higher for ready-to-drink orange juice than nectar. The same was found for the correlation of ascorbic acid content with TPC. The results confirm the contribution of the TPC to TAA.     

苹果汁中果汁含量测定方法研究

原果汁含量是苹果汁及其饮料的主要质量指标,也是判定苹果汁是否掺假的重要依据。通过对6个产地5个品种自制苹果汁的部分组分进行研究,找出与苹果汁含量有良好定量关系的特征性组分——钾、总磷和氨基酸态氮,以它们作为苹果汁含量测定参数,并且确定了各组分的标准值、权值分配方案及异常数据修正原则。据此,推导出苹果汁含量计算公式;同时按此法对自制的苹果汁和市售的6个品牌的苹果汁进行了果汁含量测定,进一步验证了此方法的可行性。此方法可用于苹果汁果汁含量测定或用于鉴别苹果汁的真伪。     

芦荟苹果复合果汁的研究

以芦荟、苹果为原料,对复合保健饮料的加工工艺进行了探讨,并对热处理、风味调配、杀菌等工序进行了重点研究,得到了合理的生产工艺和相应的工艺参数。确定了复合果汁的最佳配方为：芦荟源汁30、苹果原汁30%、柠檬酸0．15％、糖8％,在135℃5s杀菌效果最好。     

The inability of Byssochlamys fulva to produce patulin is related to absence of 6-methylsalicylic acid synthase and isoepoxydon dehydrogenase genes

Byssochlamys species are responsible for spoilage and degradation of fruits and silages. Under specific conditions they are able to produce mycotoxins. The aim of this study was to evaluate the potential of 19 different strains of Byssochlamys nivea and Byssochlamys fulva to produce patulin in relation with the presence of two genes involved in the patulin biosynthesis pathways in the genome of these fungal strains. The strains were characterized by macroscopic, microscopic examinations, internal transcribed spacer (ITS) rRNA and beta-tubulin fragment amplification and sequencing. All of the 8 B. nivea strains tested produced patulin. By contrast, none of the 11 strains of B. fulva produce this toxin. Two genes of the patulin biosynthetic pathway, a polyketide synthase (pks) and the isoepoxydon dehydrogenase (idh) were cloned from B. nivea. The deduced amino acid sequence of the polyketide synthase was 74% identical to the 6-methylsalicylic acid synthase gene of Penicillium griseofulvum and had the five functional domains characteristic of fungal type I polyketide synthases (beta-ketosynthase, acyltransferase, dehydratase, beta-ketoreductase and acyl carrier protein). The complete coding sequence of idh gene displayed after translation 88% of identity with P. griseofulvum IDH and 85% with P. expansum IDH, respectively. Both pks and idh messengers were strongly co-expressed during the production of 6-methylsalicylic acid and patulin. The presence of these genes was then investigated in the genome of B. nivea and B. fulva strains by PCR. All B. nivea strains possess the two genes, by contrast none of the B. fulva strains display these genes. The absence of 6-methylsalicylic acid and isoepoxydon dehydrogenase genes can explain the inability of B. fulva to produce patulin. In conclusion, B. fulva don't seem to be responsible for the occurrence of patulin by lack of genes.     

微胶囊型天然VE的研究

研究了喷雾干燥法制造微胶囊型VE粉末的微胶囊化工艺及技术.结果表明制造微胶囊型天然VE的壁材及其最佳组合为阿拉伯胶糊精玉米糖浆=22.5%25.O%52.5%,心材与壁材的适宜比例为65,最佳均质压力为30MPa,最佳喷雾干燥造粒工艺条件为进料温度60℃、进料流量150mL/min、进风温度195℃、出风温度70℃.