Heat-resistant fungi in the soil.

The occurrence of heat-resistant fungi has been demonstrated in samples of soil from the Slovak Republic. The heat-resistant species isolated were Byssochlamys nivea, Dichotomomyces cejpii, Eupenicillium baarnense, Neosartorya fischeri, Talaromyces avellaneus, Tal. bacillisporus, Tal. emersonii, Tal. flavus, Tal. trachyspermus, Tal. wortmanii, Botryotrichum piluliferum, Gilmaniella humicola and Nodulisporium sp. Some of them were isolated for the first time from Czechoslovakian soil. For the various soil samples examined, the occurrence of heat-resistant fungi varied qualitatively and quantitatively. Further research is needed to identify conditions affecting the occurrence of heat-resistant fungi in soil.     

Pectinolytic and cellulolytic activities of heat resistant fungi and their macerating effects on mango and African mango

Five heat resistant fungi (HRF), Neosartorya fischeri, N fischeri var spinosa, N quadricincta, Paecilomyces varioti and Byssochlamys nivea, were studied for production of pectinolytic and cellulolytic activities. All isolates produced considerable hydrolase, lyase and pectinesterase activities. Hydrolase activities were significantly higher in fruit tissue (mango and African mango) media than in pectin medium (P < 0.01) when assayed by both cup plate and viscometric methods. Activities produced in both fruit media were comparable in N fischeri, N fischeri var spinosa and P varioti but not in N quadricincta and B nivea. All isolates produced greater lyase activities in pectin medium than in fruit tissue media except for N quadricincta, while the converse was the case for pectinesterase. P varioti did not utilise carboxymethyl cellulose or produce cellulase activity. Other isolates produced cellulase with B nivea producing the greatest activity. Each isolate caused considerable maceration of artificially inoculated mango and African mango fruits, which is not directly related to measurable pectinase or cellulase. The possibility of co‐operation between pectinase and cellulase activities in the disintegration of fruit tissues is discussed. © 1999 Society of Chemical Industry     

Growth modelling of heat-resistant fungi: the effect of water activity

Growth of three strains of heat-resistant fungi, Byssochlamys fulva, Neosartorya fischeri and Talaromyces avellaneus, was studied at 25 degrees C at eight or nine water activities (a(w)) adjusted with sucrose between 0.995 and 0.85. The flexible growth model of Baranyi describing the change in colony diameter (mm) with respect to time was first fitted to measured growth data and from the fitted curves the maximum colony growth rates were estimated. These values were fitted with respect to a(w) to predict colony growth rates at any a(w) within the range tested. Optimum a(w) values of 0.986, 0.985, and 0.990 for growth, and maximum colony growth rates of 12.6, 13.2 and 20.2 mm d(-1), respectively, were calculated. The time to reach a colony diameter of 3 mm and the optimum a(w) for each strain were also calculated. The results can be applied to the prevention of spoilage of canned fruit or juices and other heat processed fruit based products.     

Fungi and decay associated with wild mango fruits (Irvingia gabonensis) under different postharvest conditions

Fungi and percentage decay associated with wild mango fruits during storage at different postharvest conditions were monitored. In addition the effect of chemical treatments (hot water, solutions of benomyl, sodium acetate and sodium metabisulphite) and film packaging on percentage rate of decay was investigated. The characteristic brownish black rot, brownish discolouration and rotting of tissue, and greenish-black soft rot common in wild mango fruits during storage are associated with fungi of the genera Aspergillus, Botrytis and Penicillium. The use of hot water, hot benomyl, hot sodium dehydroacetate and hot sodium metabisulphite (55 °C each) dips alone, or in combination with film packaging helped in reducing postharvest decay of wild mango fruits. Varietal differences in susceptibility of wild mango fruits to decay was also observed.     

Influence of ethanol and heat on disease control and quality in stored mango fruits

Pestalotia mangiferae and Curvularia lunata are the main postharvest fungi of mango cv. ‘Tommy Atkins’ causing serious economic losses during storage. Two substitutes of synthetic postharvest fungicides were tested: ethanol and heat, separately and combined at different concentrations and temperatures. Experiments were carried out in vitro to evaluate mycelial growth and spore germination and directly on mango fruits to evaluate the combination of ethanol with heat on disease incidence and on fruit quality. Storage period was of 12-days at 25 °C. Response of P. mangiferae and C. lunata towards the application of ethanol and temperature was very similar. When trials were carried out separately, ethanol at 400 ml/L completely inhibited growth of both fungi while mycelial growth reached approximately only 35 mm or less at concentrations up to 400 ml/L. Germination was severely affected by ethanol application at concentrations up to 100 ml/L. The combination of both factors also influenced fungi development affecting their conidia more than their mycelium. A complete disease control of mango fruits was achieved at 300 ml/L ethanol with 50 °C temperature. The changes in weight loss, firmness, color, acidity, SSC and, pH values of the treated and untreated mango fruits followed the normal ripening evolution.     

成熟度对芒果果实挥发物的影响

选用不同成熟度的海南小芒果为原料,以固相微萃取(SPME)技术为香气富集方法,气相色谱- 质谱联用(GC-MS)分析研究成熟度对芒果果实挥发物种类及其相对含量的影响。结果表明：芒果香气成分丰富,共检出56种香气成分,分为萜烯类、烃类、醛类、酮类、醇类、酯类6 类,其中萜烯类是主要成分,其随成熟度增加 而在果皮与果肉中相对含量降低,在半熟时最低,其中单萜相对含量大于倍半萜。果皮与果肉中酯类在绿熟时已经形成,并且在半熟时相对含量最高;随成熟度的增加果皮中醇类相对含量增大,但果肉中醇类则是在半熟时高度积累;醛类在果皮与果肉积累的成熟度不一样,分别是成熟和半熟;烃在果肉中逐渐降低,却在半熟果皮中含量最高。大多数芒果挥发物在半熟时形成,在此时对芒果果实进行调控,对提高芒果香气品质具有重要意义。     

Antimicrobial activity of vanillin against spoilage microorganisms in stored fresh-cut mangoes

The antimicrobial activity of vanillin against four bacteria (Pantoea agglomerans, Aeromonas enteropelogenes, Micrococcus lylae, and Sphingobacterium spiritovorun), four fungi (Alternaria sp., Aspergillus sp., Penicillium sp., and Fusarium sp.), and three unidentified yeasts isolated from spoiling fresh-cut mango slices was verified in laboratory media adjusted to pH 5.0. MICs of vanillin against the fungi (12.5 to 13.3 mM), bacteria (10 to 13.3 mM), and yeasts (5.0 to 6.7 mM) indicated that all the test species were sensitive to the antimicrobial effects of vanillin. Fresh-cut mango slices were dipped for 1 min in solutions containing 40 and 80 mM vanillin before being packaged in rigid trays and stored at 5 and 10 degrees C to verify the effects of vanillin on the development of the spoilage microflora. Microbiological analysis for up to 14 days of storage revealed that treatment with 80 mM vanillin significantly delayed (P < 0.05) the development of total aerobic bacteria and yeast and mold populations. Vanillin may be a practical preservative for processing fresh-cut mango.     

Heat-resistant fungi in Nigerian heat-processed fruit juices

Sixty packaged heat-processed Nigerian fruit juices consisting of 15 each of mango, orange, pineapple and tomato, were screened for the presence of heat-resistant fungi after storage at approximately 28°C for 30 days. The resulting fungal growth was purified on potato dextrose agar. Approximately 17% of all the fruit juice packages and 27% of mango and tomato juices contained heat-resistant fungi. These were identified as Paecilomyces variotii, Aspergillus tamarii, A. flavus and A. ochraceus , the latter being predominant.     

EVALUATION OF AMOMUM SUBULATUM ROXB OIL AS A SOURCE OF BOTANICAL FUNGITOXICANT FOR THE PROTECTION OF MANGO FRUITS FROM FUNGAL ROTTING

The essential oil extracted from the leaves of Amomum subulatum Roxb. (Zingiberaceae) has been evaluated for efficacy in the control of mango fruit rotting due to fungal infections. The essential oil of A. subulatum exhibited absolute antifungal activity against two mango rotting fungi viz. Botryodiplodia theobromae Pat. and Colletotrichum gloeosporioides Penz, the common storage fungi causing stem end rot and anthracnose disease of mango fruits. The oil showed its absolute fungitoxicity at the minimum inhibitory concentration of 500 µL/L. Its fungitoxic potency did not alter even on a high inoculum density of the test fungi. The Amomum oil significantly enhanced the shelf life of mango fruits by controlling anthracnose disease as well as stem end rot for an additional five and six days, respectively. The oil also inhibited pectinase and cellulase enzymes secreted by the test fungi during pathogenesis and exhibited a wide range of fungitoxicity against 13 fungal isolates. Gas chromatography-mass spectrometry analysis of the oil found 1, 8 cineole to be a major component. The LD₅₀ of Amomum oil was found to be 22,070 mg/kg of body weight in mice ( Mus musculus L.) when administered for acute oral toxicity. Keeping in view the side effects of synthetic fungicides, A. subulatum oil may be recommended as a botanical fungitoxicant of plant origin to control the rotting of mango fruits and to enhance their shelf life because of its nonmammalian toxicity and in vivo efficacy.     

Evaluation of lactoperoxidase system treatment to reduce anthracnose, stem-end rot, and bacterial black spot development during storage of mangoes

The lactoperoxidase system (LPS) was evaluated for the prevention of postharvest diseases caused by Xanthomonas campestris, Botryodiplodia theobromae, and Colletotrichum gloeosporioides in 'Keitt' and 'Kent' mangoes. The LPS treatment significantly reduced the disease development on both cultivars after storage at 12 degrees C for 2 weeks, which was followed by a ripening at 25 degrees C. The LPS treatment did not alter the sensory quality of mango fruits (color, firmness, titrable acidity, and total soluble solids) when compared to untreated fruits. The LPS thus presents good potential alternative to the chemical fungicides traditionally used to improve the shelf life of mangoes.     

绿色木霉菌发酵液对芒果采后病害及品质的影响

研究木霉菌发酵液对控制芒果采后病害及腐烂的作用。以紫花芒果果实为材料,使用绿色木霉菌(Trichoderma viride Pers.ex Fr.)发酵液涂抹果实,于(30±5)℃、相对湿度90%～95%贮藏,测定果实病斑数及面积、硬度和色泽指数。结果表明：紫花芒果贮藏至第9天,T. viride发酵液处理组腐烂指数仅为31.1%,对照组腐烂指数则达51.9%;损伤接种至7d时,T. viride发酵液处理组的病斑面积比对照组的小69.7%;贮藏至30d,T. viride发酵液处理的芒果自然发病率较清水处理组的低36.7%。T. viride发酵液处理组的芒果在贮藏6d后变软,比对照组延缓了3d。T. viride发酵液混合CMC处理的果实转黄速度较对照组延缓了3d。T. viride发酵液可显著减低损伤接种芒果的腐烂指数、病斑面积和接种发病率。     

Patterns of Peroxidase in Ripening Mango (Mangifera indica, L.) Fruits

Chemical and biochemical changes in Lippens and Smith mango cultivars stored at 12°C and 85–90% RH were studied. The observed chemical changes were similar in both varieties. Peroxidase (POD) activity increased in pulp tissues up to the climacteric stage of ripening. In a parallel way, the quantity of extractable proteins decreased from preclimacteric to ripe or senescent fruits. Polyacrylamide gel electrophoresis of the extracts from Smith mangoes revealed three isoenzymes of POD which moved towards the anode at pH 8.3. The isoenzyme pattern of POD of Lippens mango extracts was quite different, showing four faster moving bands in addition to the above mentioned three characteristic bands of Smith mango fruits. Relative activity of the different isoenzymes changed during ripening may provide insight into the ripening process.     

芒果果实中农药残留分布及慢性膳食摄入风险

为掌握常用农药在芒果果实中的残留分布情况及其对慢性膳食摄入风险的贡献大小.采用气相色谱和超高效液相色谱-串联质谱法测定样品中42个常用农药残留.采用点评估方法计算检出农药对儿童和成人的慢性膳食摄入风险的贡献份额,采用相对效能因子法计算农药的累积风险.44.1％的全果样品和35.5％的果肉样品中检出农药残留.吡虫啉在全果...     

钙处理结合壳聚糖涂膜对芒果贮藏品质的影响

以“桂热82”号芒果为试材,在贮藏前进行浸钙处理和壳聚糖涂膜处理。结果表明：不同浓度钙结合壳聚糖涂膜处理在一定程度均能提高芒果果实耐贮性与品质,其各项指标均优于单纯的涂膜处理。1% CaCl2+1%壳聚糖涂膜和3% CaCl2+1% 壳聚糖涂膜在贮藏期间均品质维持良好且稳定,能有效地抑制可溶性固形物的升高、可滴定酸的降低、果肉颜色的褐变、果肉硬度的下降、VC 含量的下降、果皮转黄指数的上升,其腐烂与失重也得到了较好的控制,其中1% CaCl2+1% 壳聚糖涂膜处理贮藏品质更显著。     

MICROBIOLOGICAL AND CHEMICAL PROPERTIES OF IRRADIATED MANGO

Fourteen fungal species belonging to five genera , Aspergillus, Cladosporium, Penicillium, Fusarium and Scoplariopsis were isolated from the surface of mango fruits , (Mangifera indica L.) variety "Zebda". Mycotoxin production by isolated molds was tested in Czapek-Dox broth as well as mango pulp. The irradiation decimal reduction doses (D₁₀ values) of the molds were determined in either physiological saline solution or mango pulp. The effects of ionizing radiation in combination with hot water-dipping (55C/5 min) on shelf-life extension and the microbiological, chemical, rheological and organoleptic properties of mango fruit (at mature green stage) stored at 12°C and 80–85% relative humidity were determined. Results showed that Zebda mango irradiated with doses of 1.0 kGy can be stored 50 days at 12°C without any undesirable changes to measured nutrient and sensory quality when compared to unirradiated mangoes refrigerated for 25 days.     

TEXTURE PROFILE OF IRRADIATED MANGOES AND PEACHES*

The mechanical characteristics of the texture profile of Kent mango and Loring, Redskin and Suwannee peach fruits were determined. Irradiation at 150 or 300 krad as well as storage at 20°C decreased all of the measured parameters with the exception of mango cohesiveness which increased during storage. Hardness, gumminess and chewiness of irradiated Loring peaches reflected the sensory hardness ratings to a greater extent than did the puncture or shear forces.     

Quantitative analysis of mycoflora on commercial domestic fruits in Japan

A comprehensive and quantitative analysis of the mycoflora on the surface of commercial fruit was performed. Nine kinds of fruits grown in Japan were tested. Overall fungal counts on the fruits ranged from 3.1 to 6.5 log CFU/g. The mean percentages of the total yeast counts were higher than those of molds in samples of apples, Japanese pears, and strawberries, ranging from 58.5 to 67.0%, and were lower than those of molds in samples of the other six fruits, ranging from 9.8 to 48.3%. Cladosporium was the most frequent fungus and was found in samples of all nine types of fruits, followed by Penicillium found in eight types of fruits. The fungi with the highest total counts in samples of the various fruits were Acremonium in cantaloupe melons (47.6% of the total fungal count), Aspergillus in grapes (32.2%), Aureobasidium in apples (21.3%), blueberries (63.6%), and peaches (33.6%), Cladosporium in strawberries (38.4%), Cryptococcus in Japanese pears (37.6%), Penicillium in mandarins (22.3%), and Sporobolomyces in lemons (26.9%). These results demonstrated that the mycoflora on the surfaces of these fruits mainly consists of common pre- and postharvest inhabitants of the plants or in the environment; fungi that produce mycotoxins or cause market diseases were not prominent in the mycoflora of healthy fruits. These findings suggest fruits should be handled carefully with consideration given to fungal contaminants, including nonpathogenic fungi, to control the quality of fruits and processed fruit products.     

柠檬酸处理对采后芒果保鲜效果的影响

为探索芒果采后果实保鲜新方法,“台农一号”芒果采后分别经0(对照)、5、10mmol/L 柠檬酸浸果10min后,常温贮藏,定期检测果实的常规品质、成熟进程和病情发展的变化。结果表明：柠檬酸处理使果实软化、果肉可溶性固形物增加及可滴定酸含量降低的速率减缓,果实的转黄指数和病情指数降低,说明适当水平的柠檬酸处理能有效延缓芒果采后果实的成熟进程,并且抑制果实腐烂发生。柠檬酸处理是芒果采后贮藏保鲜的一种可选新方法。     

Modulation of thermal resistance of ascospores of Neosartorya fischeri by acidulants and preservatives in mango and grape juice

Minimal thermal processing is desirable for near natural organoleptic and nutritional qualities of fruit based products. In the present investigation, the effect of heat (85°C) in combination with acidulants or common preservatives on inactivation of ascospores of Neosartorya fischeri, a heat resistant mould isolated from grapes, has been studied in mango and grape juice. The ascospores were found to survive for >300 min of heating at 70, 75 and 80°C in these fruit juices and complete inactivation required 120 min of heating at 85°C. The synergistic effect of heat and organic acids or preservatives in fruit juices was noticed. The thermal death rate (1/k_85°C) values did not vary much in the presence of lactic (20), malic (20) and citric (19) acids, but tartaric acid showed least inactivation effect (1/k_85°C=54 min) in mango juice. The 1/k_85°Cvalues for ascospores of N. fischeri in mango juice containing 0·1% of potassium sorbate or sodium benzoate or combination of both at 0·05% were found to be 44, 35 and 29 min respectively. These values were respectively, 32, 13 and 14 min in grape juice. Nearly 50 and 67% of the heating time was reduced by the use of potassium sorbate and sodium benzoate (0·05% each) in mango and grape juice to inactivate 3 log number of ascospores of N. fischeri. These results may be useful in thermal processing of fruit juices.     

BIOLOGICAL VALIDATION OF TOMATO PULP CONTINUOUS HEAT PROCESS

This research validated the commercial process applied to tomato pulp (pH 4.3 and 8 Brix) packed in Tetra Brik packages. Spores of Bacillus coagulans and Neosartorya fischeri were selected as targets. The heat resistance of both microorganisms, tested independently, was compared. The redesigned thermal processes were carried out in a aseptic processing and tested by indirect inoculation and retrieval with spores immobilized in alginate/tomato balls. The results showed that processes for 30 s at 115C or greater did not allow the survival of heat‐resistant molds. For bacterial spores, processes for 30 s at 109C or greater showed no survivors. Although, 30 s at 115C will control both types of spoilage spores, concern for possible C. botulinum growth attributed to metabiosis in product with varying initial populations of molds and residual oxygen content dictated, a process recommendation of 60 s at 126C for safety reasons.