二氧化钛纳米管光催化降解苹果汁中展青霉素的工艺优化

为评价二氧化钛纳米管对苹果汁中展青霉素的光催化降解性能,本文进行了光催化降解展青霉素的工艺研究,首先利用水热法制备出二氧化钛纳米管,以其光催化降解展青霉素所用时间作为活性评价指标,考察了紫外灯功率、反应温度、pH及二氧化钛纳米管的投加量对展青霉素降解效果的影响;然后据此设计正交试验进行二氧化钛纳米管光催化降解展青霉素的工艺优化。结果表明:二氧化钛纳米管与二氧化钛光催化降解模拟汁中展青霉素的活性对比结果显示,二氧化钛纳米管比二氧化钛表现出更高的光催化降解展青霉素的活性;二氧化钛纳米管光催化降解展青霉素的最佳工艺为:二氧化钛纳米管的投加量为500 mg/L,紫外灯功率为21 W,反应温度为25℃;在最佳工艺条件下,当反应体系中展青霉素的初始浓度为1000 μg/L时,二氧化钛纳米管光催化降解模拟汁与苹果汁中展青霉素的活性对比结果显示,25 min内可将模拟汁中的展青霉素含量降低到检测限以下,45 min内可将苹果汁中的展青霉素含量降低到检测限以下。     

Patulin reduction in apple juice from concentrate by UV radiation and comparison of kinetic degradation models between apple juice and apple cider

Patulin, a mycotoxin produced by several genera of fungi, including Byssochlamys, Aspergillus, and Penicillium, has been an important concern in apple cider and apple juice due to its toxicity and health consequences. In this study, the effects of UV on the patulin level, physical and chemical properties, and sensory attributes in apple juice from concentrate were investigated. Kinetic modeling of patulin reduction by UV radiation in apple juice from concentrate was calculated and compared with the degradation rate observed previously in apple cider. From an initial patulin contamination of approximately 1,000 ppb (μg/liter), the UV exposure, ranging from 14.2 mJ/cm(2) (one pass) to 99.4 mJ/cm(2) (seven passes), was successful in reducing patulin levels by 72.57% ± 2.76% to 5.14% ± 0.70%, respectively. Patulin reduction by UV radiation followed first-order kinetic modeling in a fashion similar to first-order microbial inactivation. An exponential correlation between UV exposure and the percentage of patulin remaining was observed, giving an r(2) value of 0.9950. Apple juice was repeatedly exposed to 14.2 mJ/cm(2) for each treatment, and patulin levels were significantly decreased when compared with the level obtained with the previous UV exposure treatment. While there were no significant differences in the percentages of titratable acidity and ascorbic acid (P > 0.05), there were minor yet random sampling differences in pH and degrees Brix (1 °Brix is 1 g of sucrose in 100 g of solution; the °Brix represents the soluble solids content of the solution as percentage by weight [%, wt/wt]) (P ≤ 0.05). A significant difference (P ≤ 0.05) in sensory perception for the finished apple juice was detected between the control and the full seven-pass UV radiation treatment using an experienced consumer panel and a triangle test. Patulin reduction by UV radiation from both the current study and a previous study involving apple cider was compared, which showed that both matrices strongly fit a first-order kinetic degradation model. However, the kinetic constant for degradation in apple juice was approximately 5.5 times greater than that observed in an apple cider matrix.     

Patulin in apple-based foods: occurrence and safety evaluation

Patulin is a mycotoxin produced by certain species of Penicillium and Aspergillus, often detectable in mouldy fruits and their derivatives. On the basis of a PMTDI of 0.4 mu g/kg bw, limit values of 50 mu g/kg or 50 mu g/l of patulin have been set in fruit derivatives. To estimate the quantity of patulin that can be taken in with the diet, we analysed by HPL C samples of apples and apple derivatives which are most likely to be contaminated with patulin. In apple juices and in homogenized babyfoods, the mycotoxin concentration was always below the established limits, while in some samples of juice with pulp the mycotoxin content exceeded the safe levels. In rotten apples, not only was the amount of patulin extraordinarily high in the rotten area, but the mycotoxin had also spread to the part unaffected by mould. The data presented in this study indicate that the intake of patulin with apple derivatives is usually below the tolerable level of 0.4 mu g/kg bw/day, but since the patulin content in apples can vary considerably, the quality of fruits used in the production of apple derivatives should be strictly controlled in order not to exceed the safe limits.     

Exposure to patulin from consumption of apple-based products.

Patulin is a mycotoxin produced by species of Penicillium, Aspergillus and Byssochylamys. Several Scientific Committees classify patulin as mutagenic, embryotoxic and immunotoxic. It has been found as a natural contaminant of processed apple products and its presence may be indicative of the quality of fruit used in production. In this work, a method for the analysis of patulin is described, based on a simple liquid-liquid extraction with acetonitrile; patulin is analyzed using liquid chromatography with UV detection. Patulin identity was confirmed by GC-MS after its reaction with N-methyl-N-(trimethylsilyl)trifluoroacetamide. Fifty-three apple-containing products were analyzed and patulin was detected in 14 samples in a range 1.5-50.9 microg l(-1); six of which were above the maximum permitted level of the European Union. Based on these results and juice consumption by the Spanish adult population, patulin estimated intake was 0.42 ng kg(-1) body weight per day.     

Reducing patulin contamination in apple juice by using inactive yeast

The mycotoxin, patulin (4-hydroxy-4H-furo[3,2c]pyran-2[6H]-one), is a secondary metabolite produced mainly in rotten parts of fruits and vegetables, most notably apples and apple products, by a wide range of fungal species in the genera Penicillium, Aspergillus, and Byssochlamys. Due to its mutagenic and teratogenic nature and possible health risks to consumers, many countries have regulations to reduce levels of patulin in apple products. In the present study, reduction of patulin contamination in apple juice by using 10 different inactivated yeast strains was assessed. Our results indicated that nearly twofold differences in biomass existed among the 10 yeast strains. Eight of the 10 inactivated yeast strains could provide >50% patulin reduction in apple juice within 24 h, with the highest reduction rate being >72%. Furthermore, juice quality parameters, i.e., degrees Brix, total sugar, titratable acidity, color value, and clarity, of the treated apple juice were very similar to those of the untreated patulin-free juice. Potential applications of using inactivated yeast strain for patulin control are also discussed.     

Quantitative analysis of patulin in apple juice by thin-layer chromatography using a charge coupled device detector

A method was developed and validated in-house for the detection and quantification of patulin in apple juice concentrate using a charge coupled device (CCD) on thin-layer chromatography (TLC) plates. Samples were extracted with ethyl acetate and then cleaned-up by extraction with a sodium carbonate solution. The method showed a mean recovery of 95%. The quantification and detection limit were 14 µg l^?1 and 0.005 µg per spot, respectively. The CCD camera is sufficiently sensitive to detect changes in spot fluorescence intensity caused by small differences in mycotoxin concentration under homogeneous illumination from a UV light source. The results of validation confirmed the efficiency of the method, which is sensitive enough to be used to quantify patulin in apple juice by producers or for government monitoring/survey programs. The method was applied to the analysis of 16 apple juice concentrate samples and patulin levels ranged from 15 to 46 µg l^?1. This study demonstrated the applicability of the TLC–CCD technique as a tool for monitoring patulin in apple juice.     

Detection of patulin in apple juices marketed in the Tohoku district, Japan

Patulin is a mycotoxin mainly produced by Penicillium and Aspergillus. We investigated the incidence of patulin contamination in 179 samples of apple juice and 9 samples of mixed juice (containing apple juice concentrate as an ingredient) commercially available in the Tohoku district of Japan. Patulin was detected in 3 of 143 samples containing domestic fruits and in 6 of 45 samples containing imported products and products produced in Japan using imported apple juice concentrate. Patulin analyses were carried out using high-pressure liquid chromatography with a detection limit of 4 microg/liter. The patulin content of contaminated domestic samples (three samples with concentrations ranging from 6 to 10 microg/liter), imported samples (one sample with a concentration of 15 microg/liter), and domestic samples produced containing imported concentrate (five samples with concentrations ranging from 6 to 9 microg/liter) was lower than the maximum limit of 50 microg/liter currently adopted by many countries, including Japan.     

Reduction of patulin during apple juice clarification

Patulin is a mycotoxin produced by a number of molds involved in fruit spoilage. This compound is carcinogenic and teratogenic. Various methods are currently used to reduce the levels of patulin in apple juice, namely, charcoal treatment, chemical preservation (sulfur dioxide), gamma irradiation, fermentation, and trimming of fungus-infected apples. Many of these processes are expensive and time-consuming. Therefore, there is a need to find a convenient and economical process to control patulin levels. This study was undertaken to evaluate the effectiveness of several clarification processes for the reduction of patulin. Clarification was carried out on a laboratory scale. Apple pulp was spiked with patulin, pressed, and clarified using four different processes, namely, fining with bentonite, enzyme (pectinase) treatment, paper filtration, and centrifugation. Patulin was recovered from the clarified juice by liquid-liquid extraction, and solid-phase chromatography was used for sample clean-up prior to analysis by high-performance liquid chromatography (HPLC). The minimum detectable limit using HPLC was 20 microg/liter. Pressing followed by centrifugation resulted in an average toxin reduction of 89%. Total toxin reduction using filtration, enzyme treatment, and fining were 70, 73, and 77%, respectively. Patulin reduction was due to the binding of the toxin to solid substrates that was verified by analyzing the clarified juice as well as the filter cake, pellet, and sediment. The combined concentrations correlated to the spiked concentration. These results reveal that clarification was successful in the reduction of patulin levels in apple juice. However, clarification resulted in high levels of patulin in the pressed pulp after filtration and centrifugation, and this could be harmful if they are used as animal feeds.     

Evaluation of several culture media for production of patulin by Penicillium species

The aim of this study was to evaluate different species of Penicillium to identify those which have the potential to produce the greatest amount of the mycotoxin, patulin. Additionally, six different culture media were compared to determine maximum patulin production. Eleven different strains of Penicillium species were selected because they had previously been reported to be producers of patulin. The strains included Penicillium expansum, Penicillium griseofulvum (formerly Penicillium urticae), Penicillium clavigerum, and Penicillium coprobium and a recent Penicillium sp. isolated from an apple. Cultures were grown in duplicate in three different liquid media: potato dextrose, malt extract, and glucose/yeast extract/peptone, both with and without manganese supplementation. Patulin production was compared at 24, 48, 72, and 96 h. Variability in patulin production occurred among the different species, growth media used, and time of incubation. All three of the P. griseofulvum isolates were the highest producers of patulin at 96 h. For most of the strains, potato dextrose broth supplemented with manganese was optimal for maximum production of patulin. Although P. expansum is frequently cited as the most likely source of patulin in apple juice, certain other Penicillium species are capable of producing more patulin than strains of P. expansum. The apple juice industry should be alert to the possibility that Penicillium species other than P. expansum can be responsible for the occurrence of patulin.     

A limited survey of retail apple and grape juices for the mycotoxin patulin

A retail survey (38 samples) of apple, grape and other juice-based products for the mycotoxin patulin has been carried out using HPLC analysis. Positive results were confirmed by GC-MS of the TMS derivative using chemical ionization selected ion monitoring. No grape juice or mixed juice product contained detectable patulin (limit 5 micrograms/l), nor did the majority (58%) of the apple juices. Low levels of patulin (in the range 5-10 micrograms/l) were present in six apple juices and the remaining four positive samples contained 16, 18, 30 and 56 micrograms/l.     

利用Saccharomyces cerevisiae KD控制苹果汁中棒曲霉素的污染

研究一株食品生产用酿酒酵母Saccharomyces cerevisiae KD在培养基及市售100%苹果汁中对棒曲霉素污染的控制作用。通过高效液相色谱法对棒曲霉素进行定量,分析起始棒曲霉素浓度、菌体接种量和培养基pH对S. cerevisiae KD去除棒曲霉素活力的影响;利用酶标仪监测S. cerevisiae KD的生长状况,且通过检测可溶性固形物、酸度、总酚、黄酮含量对菌体发酵后苹果汁的品质进行了评估。结果表明:有氧条件下S. cerevisiae KD能够在28 h内完全去除培养基中的棒曲霉素,其去除机理包括物理吸附和酶解;在较低的起始棒曲霉素浓度和较高的菌体接种量条件下,S. cerevisiae KD对棒曲霉素的去除率较高,但在培养后期,不同菌体接种量下棒曲霉素的去除率接近一致;实验还发现酸性条件有利于S. cerevisiae KD去除棒曲霉素。此外,S. cerevisiae KD对棒曲霉素的耐受性较强,甚至在棒曲霉素浓度高达100 mg/L的环境中依然能较好生长。在市售100%苹果汁中,S. cerevisiae KD也能高效控制棒曲霉素的污染,且与Lactococcus lactis MG1363联合发酵2 d后,果汁中已无棒曲霉素检出,总酚含量显著高于发酵前苹果汁(p<0.05),发酵果汁的品质较好。结论:S. cerevisiae KD可有效控制食品中棒曲霉素的污染,具有潜在的应用前景。     

Production and degradation of patulin by paecilomyces species,a common contaminant of silage

The production and degradation of patulin by a common silage comtaminant, Paecilomyces sp., is described. Utilising protoplasts of the parent organism, 80% degradation of radiolabelled patulin occurs over the 3-h period studied and it is proposed that this degradation effect may account for anomalies in the investigation of suspected mycotoxin poisoning.     

拟粉红锁掷孢酵母降解展青霉素的机制

展青霉素(PAT)是一类主要由曲霉属和青霉属等真菌产生的有毒次级代谢产物,主要污染水果及其制品,严重威胁着人类的健康。为了寻找一种安全高效的PAT脱毒方法,近年来采用生物法清除PAT已成为主要的研究方向。作者研究了拟粉红锁掷孢酵母(Sporidiobolus pararoseus)对PAT降解的影响及其降解机制。结果显示,S.pararoseus可以显著降低苹果伤口处PAT的积累量,体外实验发现S.pararoseus与PAT(5μg/mL)共同培养18 h,PAT可以被S.pararoseus完全降解。S.pararoseus对PAT的降解作用既不是酵母细胞壁的吸附作用,也不是细胞的吸收作用,而是细胞正常代谢下产生的胞内酶对PAT具有降解作用。本研究有助于了解S.pararoseus降解PAT的作用机制,为真菌毒素的生物降解提供了新的理论依据。     

Contamination of food products with patulin

Based on the method for patulin determination designed by the authors the rate and level of contamination of fruit, vegetables and foods manufactured from them (juices, purees, jams) with this mycotoxin were studied. Patulin was found in 8 out of 160 samples of fruit and vegetables, the highest concentration of patulin was identified in the berries of sea buckthorn (up to 54 000 micrograms/kg). Patulin was found in 28 out of 185 samples of foods manufactured from fruit. The concentration of patulin in juices did not exceed the allowable concentrations on the average. Patulin was largely identified in apple, sea buckthorn and plum juices.     

Fate of patulin in the presence of the yeast Saccharomyces cerevisiae

Patulin is known to become analytically non-detectable during the production of cider from contaminated apple juice. The fate of [¹⁴C]-labelled patulin during the alcoholic fermentation of apple juice was studied. Three commercial cider strains of Saccharomyces cerevisiae degraded patulin during active fermentative growth, but not when growing aerobically. The products of patulin degradation were more polar than patulin itself and remained in the clarified fermented cider. Patulin did not appear to bind to yeast cells or apple juice sediment in these model experiments. HPLC analysis of patulin-spiked fermentations showed the appearance of two major metabolites, one of which corresponded by both TLC and HPLC to E-ascladiol prepared by the chemical reduction of patulin using sodium borohydride. Using a diode array detector, both metabolites had a λ_max = 271nm, identical to that of ascladiol. Thenmr spectrum of a crude preparation of these metabolites showed signals corresponding to those of the E-ascladiol prepared chemically and a weaker set of signals corresponding to those reported in the literature for Z-ascladiol.     

Purification of patulin from Penicillium expansum culture: high-speed counter-current chromatography (HSCCC) versus preparative high-performance liquid chromatography (prep-HPLC)

Patulin is a mycotoxin produced by species of Penicillium and Aspergillus and is toxic to a wide range of organisms, including humans and livestock. To produce large amount of pure patulin for research purposes, high-speed counter-current chromatography (HSCCC) and preparative high-performance liquid chromatography (prep-HPLC) were applied to the purification of patulin. Apple juice was inoculated with P. expansum and containing 0.5 mg patulin per ml was used as a starting material for separation. For HSCCC, a biphasic solvent system consisted of ethyl acetate–hexane–pH 4 acetic acid (7.5:2.5:10, v/v/v) was used. For prep-HPLC, the separation was carried out in a C18 reversed-phase preparative column with a mobile phase containing acetonitrile–pH 4 acetic acid (5:95, v/v). Fractions containing patulin were collected and analysed by analytical HPLC and identified by congruent retention time and ultraviolet/visible (UV–VIS) spectrum of the standard. The structure of the purified patulin was confirmed by mass spectrometry and nuclear magnetic resonance. HSCCC produced 21.9 mg of patulin from 50 ml apple juice culture whereas the prep-HPLC yielded 18.1 mg. HSCCC also produced purer patulin than the prep-HPLC (98.6 versus 96.3%) and higher recovery (86.2 versus 71.3%). In addition, the HSCCC method is advantageous for its lower cost and a simpler procedure compared with the prep-HPLC. This one-step HSCCC method can potentially provide a simple, effective and environmentally friendly tool for obtaining gram-level pure patulin for toxicology, detoxification and many other patulin-related studies.     

The microbiology of apples and apple products

The apple industry has reached an annual production level of 8.5 billion pounds. CA storage of 25% of this crop has enabled a fresh market on a year‐round basis. To achieve high quality in raw fruit and processed apple products, careful attention must be paid to maintaining a microbiologically stable environment. The ecology of the microflora associated with the apple is a reflection of the orchard, handling, harvesting, and storage practices. Yeasts#lbpredominate on orchard fruit, molds may become a storage problem, and bacteria cause spoilage, off flavors, and loss of quality in juice products. Despite the microbial problems inherent in producing of quality product, the apple industry is faced with the occurrence of patulin. Patulin, a mycotoxin produced by Penicillium and Aspergillus species, has been associated with damaged fruit. Decreased temperatures, coupled with CA storage; can deter mold growth and patulin production. Laboratory detection methods for derivations of patulin are able to detect microgram quantities. Means to eliminate patulin formed in apple products include addition of ascorbate and SO₂, extending fermentation, or charcoal filtering. However, degradation products of patulin have not been evaluated toxicologically.     

酿酒酵母发酵混合果汁的功能性研究

采用酿酒酵母Saccharomyces cerevisiae KD对苹果、猕猴桃、梨混合果汁进行发酵,研究了该混合果汁发酵过程中酿酒酵母对真菌毒素棒曲霉素的去除作用及其降解产物对大肠杆菌的毒性,并对其发酵过程中的抗氧化能力及对α-淀粉酶、脂肪酶的抑制效果进行分析。结果发现,混合果汁发酵过程中棒曲霉素的含量持续下降直至完全降解,且棒曲霉素的降解产物对大肠杆菌无毒害;对抗氧化能力指标进行检测,发现发酵果汁的DPPH·、ABTS+·清除率和还原力相比新鲜果汁分别提高了15.0%、45.9%和9.6%,抗氧化能力显著增强(P<0.05)。此外,混合发酵果汁可以有效地抑制与肥胖相关的α-淀粉酶、脂肪酶的活力,抑制率分别为52.4%和45.2%。本文的研究结果可为开发功能性发酵果汁提供科学依据和技术支持。     

Effect of irradiation and storage on patulin disappearance and some chemical constituents of apple juice concentrate

The effect of irradiation on the patulin content and on the chemical composition of apple juice concentrate during storage at 4 degrees C over a period of several weeks was investigated. The radiation-induced disappearance of the mycotoxin in relation to the absorbed dose followed an exponential relationship. The radiation dose (D50), i.e., the dose which reduced the patulin content to 50% of its initial value was equal to 0.35 kGy. Storage of the irradiated concentrate had no effect on the patulin content; however, storage did lead to a slight increase in the titratable acidity and a decrease in the amounts of the carbonyl compounds and the ascorbic acid concentration. The development of non-enzymatic browning during storage of the irradiated samples followed the same kinetics as that of the non-irradiated samples.     

Investigation of patulin contamination in apple juice sold in retail outlets in Italy and South Africa

A study of apple juice products sold in Italy and South Africa was initially carried out on 20 samples bought in Cesena, Italy, and Tygerberg in Cape Town, South Africa. The samples were bought at random and analysed for patulin contamination. All 12 of the Italian samples had no detectable levels of patulin, except one, which was just slightly above the lowest regulatory limit of 10 ng ml^-1. On the other hand, five of the eight South African samples were all contaminated with patulin levels above 10 ng ml^-1, with one showing a concentration of 75 ng ml^-1, well above the highest regulated limit of 50 ng ml^-1. This latter result led to a more targeted investigation with 14 samples being purchased in the low-income areas of Tygerberg where the initial samples were sourced. These samples confirmed that there might be a problem of mycotoxin contamination in apple juices products sold to low-income consumers because half of the samples showed patulin contamination of which four had levels well above the acceptable limits. This is the first study in South Africa to look at apple juice products in low-income areas and it points to a need to intervene and introduce quality systems in the supply chain of the manufacture and packaging of apple juice products by independent small business.