Improvement of quality and shelf-life of strawberries with edible coatings enriched with chitosan     

《Postharvest Biology and Technology》2013

Strawberry fruit have a very short shelf-life and senescent period due to their high degree of perishability and infection caused by several pathogens that can rapidly reduce fruit quality. The aim of this study was to determine the efficacy of carboxymethyl cellulose (CMC), hydroxypropylmethyl cellulose (HPMC) and composites with chitosan (CH) coatings on the shelf-life and overall quality of strawberry fruit. Strawberry fruit dipped for 2 min in solutions of CMC (1%), HPMC (1%), CMC (1%) + CH (1%) and HPMC (1%) + CH (1%) were stored at 11 ± 1 °C, 70–75% RH, while the uncoated fruit served as controls. Fruit coated with edible coatings showed significant delays in the change of weight loss, decay percentage, titratable acidity (TA), pH, total soluble solids (TSS) and ascorbic acid content as compared to uncoated control fruit. In addition, the edible coatings had a positive effect on maintaining higher concentrations of total phenolics and total anthocyanins, which decreased in control fruit due to over-ripening and senescence processes. Compared to the controls, all the coatings had positive effects on the inhibition of cell wall degrading enzymes and among all the tested coatings, CMC + CH and HPMC + CH was superior in inhibiting enzyme activity. These findings suggest that the use of CMC 1% + CH 1% and HPMC 1% + CH 1% coatings are useful for extending the shelf-life and maintaing quality of strawberry fruit.  相似文献   

Variations in soil chemical properties and microbial biomass in artificial gaps in silver fir stands     

Adele Muscolo  Maria Sidari  Roberto Mercurio 《European Journal of Forest Research》2007,126(1):59-65

Changes in soil chemical and microbiological parameters in small (185 m²) and medium (410 m²) gaps, created in mature silver fir (Abies alba Mill) stands (mean height 30 m) in the Calabrian Apennines (Southern Italy), were studied over 2 years. Medium gaps had high soil temperature and photosynthetically active radiation (PAR) transmittance and low soil moisture. Within small gaps we detected a greater amount of organic matter, with respect to under canopy cover sites and medium gaps. Moreover, a different trend of the organic matter between small and medium gaps was observed. In the medium gaps, with respect to under canopy cover sites and small gaps, we found a relatively low content of organic matter, associated to a lower amount of humic acid, which suggested that the organic substrate undergoes a mineralization rather than a humification process. An opposite trend was observed in small gaps, where the increase of organic matter content, associated to an increase of humic acid and microbial biomass, suggested a better humification process. Moreover, in small gaps the highest level of urease and the greatest fluorescein diacetate (FDA) hydrolysis were observed. The different trend of organic matter observed in small and medium gaps may be related to changes in the environmental conditions. PAR transmittance, significantly higher in medium gaps, contributed to increase soil temperature and decrease soil moisture, affecting soil microbial populations and organic matter trend. These results suggest that the creation of small gaps represents the silvicultural practice with minor environmental impact.  相似文献   

In vitro protein digestion, and growth of Atlantic salmon with different trypsin isozymes     

M. Bassompierre  T.H. Ostenfeld  E. McLean  K. Rungruangsak Torrissen 《Aquaculture International》1998,6(1):47-56

Growth and in vitro digestion was examined in three iso-trypsin phenotypes (patterns 1, 2 and 2) of Atlantic salmon, Salmo salar. Fish grew equally well during the 128 day experiment irrespective of phenotype. At day 64 and 91, weight-specific growth rate of 2 phenotype animals were significantly lower (p < 0.05). At the end of the experiment, significant differences (p < 0.05) were noted between groups with respect to size. An in vitro method was used to examine protein digestion by the different trypsin phenotypes. Three fish meals (FM I > FM II > FM III) of high, medium and low quality, as defined by chemical analyses, were used. Phenotype 1 was able to differentiate between three fish meals ranking FM I > FM II > FM III. In contrast, phenotypes 2 and 2 were not able to separate between meals. In vitro digestion efficiency was dependent upon the three salmon types, ranking phenotype 2 > 1 = 2.  相似文献   

香蕉枯萎病拮抗菌株BS11抗真菌活性物质的研究     

吴英俊  林宝英  梅双双  戎伟 《安徽农业科学》2014,(35):12505-12507,12515

[目的]对枯草芽孢杆菌BS11抗真菌活性物质进行研究,为该菌株的进一步开发应用提供参考。[方法]比较了枯草芽孢杆菌BS11在LB和NB培养基上的生长情况,比较了3种方法提取该菌株活性物质的效果,并探讨了该菌株的最佳培养条件。[结果]以香蕉枯萎病菌为指示菌,发现拮抗菌在LB和NA 2种不同培养基中有很明显的差别,LB培养基中生长繁殖速度快,但上清液活性很低,NA培养基中繁殖速度较慢,上清液活性却较好;乙醇沉淀法和乙酸乙酯萃取法均不能提取到活性物质,硫酸铵沉淀法基本上可将活性物质提取出来;BS11最佳的培养条件为初始p H7,温度30℃,通气量60 ml;发酵上清液有蛋白酶、纤维素酶活性,但没有几丁质酶活性。[结论]枯草芽孢杆菌BS11株所产的抗真菌活性物质具有性质稳定、广谱、易于提取等优点,为其应用于植物病害防治提供了理论依据。  相似文献   

不同复合酶制剂对肥育猪生长性能的影响   总被引：1，自引：0，他引：1  

王彩玲  梅红  张书明  田君  熊磊 《河南畜牧兽医(综合版)》2002,23(11):7-8

试验选用72头100日龄,体重在44kg左右的三元杂交(杜×长×大)商品代瘦肉型肥育猪,完全随机分为3个组(A、B、C),每个组24头,设三个重复。A组中,饲料中加入国产复合A酶;B组中,饲料中加入国产复合B酶;C组中,饲料中加入罗酶宝TM。经过30天的饲养试验,结果表明:①B、C两组肥育猪的日增重比A组分别提高0.81%、5.50%,C组比B组日增重提高4.65%;②C组肥育猪料重比比A组提高3.53%,C组料重比比B组提高2.59%,B组料重比比A组提高0.96%;③经济效益,C组比A、B两组分别提高8.59%、5.99%;④试验全期,三个处理组的腹泻率均极低。  相似文献   

Ca2+、PEG预处理对干旱胁迫下小麦幼苗某些酶活性的影响   总被引：13，自引：0，他引：13  

洪法水  董振吉 《作物学报》1996,22(1):101-106

本文结果表明，Ｃａ＾２＋、ＰＥＧ预处理小麦种子具有提高其幼苗ＲＷＣ及ＳＯＤ、ＣＡＴ、ＰＯＤ的活性和降低膜透性的效应，在干旱胁迫下植株生长抑制减轻。随着干旱胁迫的加强、ＳＯＤ、ＣＡＴ、ＰＯＤ活性迅速上升并始终维持较高水平，具体表现为浸种处理ＰＥＧ〉Ｃａ＾２＋〈Ｈ２Ｏ；ＲＷＣ表现为ＰＥＧ〉Ｃａ＾２＋〉Ｈ２Ｏ，植株生长抑制程度表现为ＰＥＧ〈Ｃａ＾２＋〈Ｈ２Ｏ。解除干旱胁迫后，Ｃａ＾２＋，ＰＥＧ浸种处理的  相似文献   

A method for linking in situ activities of hydrolytic enzymes to associated organisms in forest soils     

Shufu Dong  Melanie D. Jones 《Soil biology & biochemistry》2007,39(9):2414-2419

A root window-based, enzyme-imprinted, membrane system has been modified to enable visualization of the activities of hydrolytic enzymes (acid phosphatase, aminopeptidase, chitinase, and β-glucosidase) in situ in forest soils. The approach can be used to correlate the distribution of enzyme activity with visible features such as roots, mycorrhizas, or mycelial mats. In addition, it enables accurate spatial soil sampling for analysis of microbial communities associated with enzyme activities. The substrates are colorimetric conjugates of napthol, where color develops instantly in the field, or fluorimetric conjugates of 4-methylumbelliferone, whose fluorescent products are detected by a gel-documenting system. The method will allow important questions about the relationship between taxonomic and functional diversity of soil microorganisms to be addressed and identification of enzyme activity hot-spots in soil.  相似文献   

Concentration related responses of chlorpyriphos in antioxidant, anaerobic and protein synthesizing machinery of the freshwater fish, Heteropneustes fossilis     

G. Tripathi  J. Shasmal 《Pesticide biochemistry and physiology》2011,99(3):215-220

Impacts of chlorpyriphos (2, 4, 6 ppm) on the profiles of antioxidant (catalase) and anaerobic (lactate dehydrogenase) enzymes and other macromolecular contents (DNA, RNA, protein) of various tissues of the freshwater fish, Heteropneustes fossilis were studied. Chlorpyriphos significantly decreased the specific activity of catalase (CAT) and lactate dehydrogenase (LDH) in the brain, liver, gill and skeletal muscle of the fish. The reduction in specific activity might be due to the binding of chlorpyriphos or its metabolites with the enzyme molecules or affecting the synthesis and/or degradation of the enzymes. Like enzymes, the DNA, RNA and protein contents decreased in the brain, liver, gill and skeletal muscle of the fish as a function of increase in chlorpyriphos concentrations (2-6 ppm). The chlorpyriphos-induced reduction in these biochemical constituents might be because of alteration in their turnover (synthesis/degradation) in different tissues. The maximum effects on CAT, LDH, DNA, RNA and protein were obtained in response to 6 ppm chlorpyriphos. The present findings suggest chlorpyriphos concentration related impairment in antioxidative, anaerobic and protein synthesizing capacity of the fish. Therefore, the use of higher concentrations of chlorpyriphos should be avoided to protect the health of economically important freshwater food fish.  相似文献   

Soil microbial populations and activities as influenced by legume green fallow in a semiarid climate     

V.O. Biederbeck  R.P. Zentner  C.A. Campbell 《Soil biology & biochemistry》2005,37(10):1775-1784

Tilled fallow-wheat (Triticum aestivum L.) (F-W) is the most commonly used cropping system in the semiarid Canadian prairie. However, because frequent fallowing degrades soil, a partial fallow with annual legumes as green manure [i.e. ‘green fallow’ (GF)] has been proposed as a soil conserving and more bio-resource efficient alternative to bare fallow. We conducted a 6-year study to compare the influence of four GF-W, a F-W and a continuous W (Cont. W) system, on soil microbial communities, microbial biomass (MB) and activities in an Orthic Brown Chernozem, silt loam (Aridic Haploboroll) at Swift Current, Sask., Canada. The four GF legumes used were black lentil (Lens culinaris Medikus), Tangier flatpea (Lathyrus tingitanus L.), chickling vetch (Lathyrus sativus L.) and feedpea (Pisum sativum L.). They were grown to full bloom and then incorporated with a tandem disk. Analysis of soil taken from 0 to 10 cm depth after growing wheat in the sixth year of the experiment (i.e. 15 months after the most recent legume GF had been turned under) showed that most of the soil biochemical and microbiological attributes assessed were significantly improved (compared to F-W) by increasing cropping intensity (Cont. W), and even more by using the GF systems. The average improvement gained from the four GF legumes relative to F-W, was 385% for number of bacteria, 210% for filamentous fungi, 170% for MB-C, 191% for MB-N, 205% for cumulative C mineralization in 30 days at 21 °C, 202% for dehydrogenase, 171% for phosphatase, and 287% for arylsulfatase activity. The biologically active C and N, when expressed as ratios of MB-C or MB-N to total soil C or N, increased from 1.6 and 2.0% in F-W to 1.9 and 2.6% in Cont. W and to an average of 2.4 and 3.5% in GF-W. A sensitivity analysis (ratio of other treatment values to value for F-W) showed that Cont. W, and the GF-W systems even more, increased all major soil biological attributes tested. Among the GF systems, lentil-W consistently increased sensitivity the most, while Tangier flatpea-W usually increased it the least. The dynamic direct and indirect microbiological attributes were more sensitive indicators of changes in soil productivity than total organic C or N. The sensitivity of the attributes decreased in the sequence: Bacteria>Arylsulfatase>Filamentous fungi≈Cumulative C mineralization≈Dehydrogenase>MB-N>Phosphatase≈MB-C. Compared to the earlier published sensitivities of select physical and chemical attributes of soil quality to these same agronomic treatments, the microbiological attributes proved to be far more sensitive and more responsive to the beneficial influence of legume green fallowing in this semiarid loam.  相似文献   

Soil quality variables in organically and conventionally cultivated field sites     

N. Monokrousos  J.D. Diamantopoulos  G.P. Stamou 《Soil biology & biochemistry》2006,38(6):1282-1289

This study aimed to answer the following questions (a) which of the soil variables (chemical, biological, enzyme activities and potential metabolic profile based on the Biolog method) could be used as indicators reflecting differences in soil quality between organically and conventionally managed asparagus fields, (b) how the duration of organic management affects these soil variables and (c) in what extent the soil quality in organic fields is comparable to that in hedgerows. The study included four organically cultivated fields which differed in the time they enter organic treatment: 6 years (O6), 5 years (O5), 3 years (O3) and 2 years (O2), the closest to them hedgerow (Ho), a conventionally managed field (CF) and its adjacent hedgerow (Hc). Among the chemical and biological variables, those contributing for most to the discrimination of the organic and conventional fields were mainly microbial biomass C (MBC) and N (MBN) and secondly variables related to N-cycle (NO₃, N organic, rate of N mineralization). MBC and MBN were higher in organic and conventional areas, respectively, reflecting differences in the structure of their microbial communities. The chemical and biological variables did not differ among O3, O5 and O6 fields, while low values of organic N, rate of N mineralization and extractable P was recorded in O2 area. The enzyme activities of amidohydrolases (l-asparaginase,l-glutaminase, urease) and phosphatases (alkaline and acid phosphatase) were by far higher in organic areas than in the conventional one. The activities of amidohydrolases and alkaline phosphatase changed in a similar way, exhibiting higher values in O3 and O5 areas while between the oldest (O6) and the newest (O2) area no differences were recorded. While the suppress of enzyme activities in O2 was related to low inputs due to transition, the negative feedback between supply of N and P and activities in O6 was a possible explanation. The activity of acid phosphatase increased from the newest to oldest organic areas. The potential functional diversity and substrate evenness did not differ among sampling areas. Differences between areas were recorded only in relation to the carbohydrates' consumption. The soil quality of hedgerows seems to be completely different than that of the arable land in terms of all studied variables. Also, significant differences were recorded between the two hedgerows, a fact that could be related to the different management practices applied in the neighboring fields.  相似文献