Transgenic melon (cucumis melo L.) and potential for expression of novel proteins important to food industry

Abstract

Melon (Cucumis melo L.) is an important fruit crop cultivated widely in every region of the world. Our laboratory is targeting this species for production of novel proteins important to food industry. Prior to expression of protein of interest in transgenic melon an efficient genetic transformation system has to be developed. In this context we are testing a wide variety of promoters fused to reporter gene for β‐glucuronidase (GUS) for expression specifically in melon fruits. In this study in melon, salicylic acid‐inducible promoter region of pathogenesis‐related protein gene (PR1a) of tobacco fused to β‐glucuronidase (GUS) gene was introduced into melon via Agrobacterium‐mediated gene transfer using a binary vector system. Gene transfer was effective when Agrobacterium virulence factors like acetosyringone (100 μM) and low pH (5.2) were provided during the co‐culture step. Transformed shoots were recovered from benzyladenine‐induced cut cotyledons using kanamycin gene as a selective marker. Regeneration of shoots from cotyledons was stimulated by providing 10 mM proline in the shoot organogenesis medium. Southern and Northern blot analysis of transformants confirmed the presence of β‐glucuronidase gene in two selected clones J‐3 and PR‐G. The transformants also showed high β‐glucuronidase activity after salicylic acid treatment. Thiamine, a previously known inducer of pathogenesis‐related protein, stimulated β‐glucuronidase in J‐3 but not PR‐G melon transformants tested in this study. These studies showed that tobacco PR1a promoter region can be expressed in melon and it was stimulated by salicylic acid. This indicates the potential to use the promoter region of tobacco PR1a for genetic improvement of melon for specific food processing‐related characteristics or for expression of novel food‐related proteins. The promoter region could be used to drive specific target genes under stress or salicylic acid induced conditions.     

Characterisation of wines and distilled spirits from melon (Cucumis melo L.)

Melon fermentation and distillation was studied with a view to produce melon spirits. Three different substrates were obtained from melon (Cucumis melo L.). Sugar concentration was around 60–70 g L^?1 and the pH between 4.6 and 5.2. The substrates were clarified and then fermented at one of two pH levels at 20 °C. A commercial Saccharomyces cerevisiae starter culture was used to obtain melon wines with an alcohol concentration of 3.8–5.8% (v/v). The melon wines were distilled in a distillation column to yield distillates with an alcohol content of 33–60% (v/v). The major volatiles in the melon wines and in the distillates were analysed by gas chromatography (GC). The results demonstrated that melon could be a good substrate of fermentation and distillation but also yielded significant differences in the volatiles analysed in the different melon wines and distillates obtained from the different substrates in the different conditions of the experiment. Fermentation pH greatly affected the methanol, acetaldehyde, and butanol contents and thus the final quality of the spirits produced.     

Effect of ripeness on the shelf-life of fresh-cut melon preserved by modified atmosphere packaging

Fresh-cut ‘Piel de Sapo’ melon was processed at different ripeness stages and stored under modified atmosphere packaging for 35 days at 5 °C. Raw material firmness and soluble solids content ranged from 6.5 to 3.9 N and 11.1 to 14.3 °Brix, respectively. The effects of a 2.5 kPa O₂+7 kPa CO₂ packaging atmosphere and a dip of 1% ascorbic acid and 0.5% calcium chloride on physiology, microbiological stability as well as color and firmness were evaluated. An intermediate stage of ripeness at processing was the most suitable to extend the shelf-life of fresh-cut ‘Piel de Sapo’ melon. Green-mature fresh-cut melon reduced CO₂ accumulation and ethanol production. In addition, a treatment with ascorbic acid and calcium chloride in combination with modified atmosphere packaging, contributed to a greater extension of the shelf-life of fresh-cut melon than that reported for fruits stored under non-modified atmosphere, slowing down the growth of microbial populations, maintaining the original color and reducing softness. Thus, the shelf-life of green-mature fresh-cut ‘Piel de Sapo’ melon dipped in an ascorbic acid and calcium chloride solution and packaged under modified atmosphere was about 10 days.     

鲜切果蔬包装的研究现状与进展

包装在维持鲜切果蔬品质、延长货架寿命等方面发挥着重要的作用。本文综述了近年来国内外包装材料在鲜切果蔬保鲜方面的研究进展与应用。介绍了鲜切果蔬的包装技术,包括气调包装、涂膜包装和智能包装等,总结了其优缺点及应用现状,并且讨论了鲜切果蔬包装未来的发展趋势。      

不同贮藏温度对采后86-1哈密瓜果实冷害及品质的影响

为了研究不同贮藏温度对采后哈密瓜果实冷害及品质的影响,分别对1、3、5℃贮藏条件下86-1哈密瓜果实的冷害症状、冷害指数、冷害率、细胞膜相对透性、硬度、可溶性固形物含量、可滴定酸及维生素C含量进行了系统观察、统计与测定。结果表明:86-1哈密瓜冷害的发生与贮藏温度及持续时间有关,1℃贮藏条件下,86-1哈密瓜果实冷害出现的时间较早,果实的冷害指数、冷害率及细胞膜相对透性较高;硬度、可溶性固形物及维生素C含量下降较快,可滴定酸出现先上升后下降的趋势。3℃贮藏有利于维持86-1哈密瓜果实的品质,5℃贮藏果实虽未发生冷害,但后期品质劣变较快,腐烂较重。      

Modified Atmosphere Maintains Quality of Fresh-cut Cantaloupe (Cucumis melo L.)

ABSTRACT: Fresh-cut cantaloupe cubes were placed in film-sealed containers in which the internal gas mixture was attained naturally (nMAP), was flushed with 4 kPa O₂ plus 10 kPa CO₂ (fMAP), or was maintained near atmospheric levels by perforating the film (PFP). While both nMAP and fMAP maintained the salable quality of melon cubes for 9 d at 5°C, fMAP maintained quality better than nMAP. The benefit of fMAP was indicated by better color retention, and by reduced translucency, respiration rate, and microbial population compared with nMAP. Shelf life of cubes in PFP was only 5 to 7 d at 5°C, and its rapid decline was due to tissue translucency and/or off-odor development.     

Bitter melon (Momordica charantia L.) bioactive composition and health benefits: A review

Bitter melon (Momordica charantia L.) has traditionally been used as a medicinal food in many developing countries. It is a tropical fruit claimed to have therapeutic effects due to its content of bioactive compounds. The present review is an attempt to highlight the bitter melon varieties, bioactive composition that is linked to its therapeutic effects, especially antidiabetic effect, in vitro and in vivo models, and understanding of the mechanisms of actions of bitter melon that are associated with epidemiological evidences. This paper also outlines a proposed processing scheme aiming to fully utilize bitter melon and add further value to this fruit.     

The role of peroxidase on the antioxidant potential of fresh-cut ‘Piel de Sapo’ melon packaged under different modified atmospheres

The effects of different initial in-package O₂ and CO₂ concentrations (2.5 kPa O₂ + 7 kPa CO₂, 10 kPa O₂ + 7 kPa CO₂, 21 kPa O₂, 30 kPa O₂ and 70 kPa O₂) on peroxidase activity, vitamin C content, total phenolics and antioxidant capacity of fresh-cut ‘Piel de Sapo’ melon have been investigated for 14 days at 4 °C. The radical scavenging activity of fresh-cut melon strongly increased after 9 days storage related to a synthesis of phenolic compounds, especially under 2.5 kPa O₂ + 7 kPa CO₂ atmospheres. Low O₂ levels best maintained vitamin C and phenolic content during the storage. However, stressful too-low O₂ and high CO₂ levels induced an important increase of peroxidase activity under 2.5 kPa O₂ + 7 kPa CO₂ atmosphere, which was directly related to changes of vitamin C throughout storage. Therefore, 70 kPa O₂ atmospheres are proposed to prevent anaerobic conditions during storage of fresh-cut melon and thus, reduce wounding stress and deteriorative changes related to high peroxidase activity in tissue.     

哈茨木霉菌剂处理提高网纹甜瓜(Cucumis melo L. var. reticulatus Naud.)的货架期品质

该研究探讨了哈茨木霉菌剂处理对网纹甜瓜货架期品质的影响。研究在网纹甜瓜种植过程中,对甜瓜根部施用哈茨木霉菌剂4次（每次剂量为0.1 g/m2）,以根部施用清水为对照组,比较果实在10 ℃冷库中贮藏第0、5、10和15 d的感官得分、颜色、质构、口味和抗氧化能力等品质特征。结果表明：哈茨木霉处理后果肉的口感甜糯,质地均一,果实最佳赏味期较对照组延长约4 d;哈茨木霉处理组果实可溶性固形物含量和Vc含量分别比对照组提高15.20%和64.58%;哈茨木霉组的ORAC值达到667.80 (µmol/L)/100 g,比对照组提高了10.05%,果实的抗氧化能力显著性提高;并且哈茨木霉处理使果皮硬度提高1.75倍,延缓果肉的软化现象,使果实更加便适于贮藏和运输。因此,种植过程中在根部追施哈茨木霉菌剂有利于提高网纹甜瓜货架期品质。     

Innovative processes and technologies for modified atmosphere packaging of fresh and fresh-cut fruits and vegetables

Modified atmosphere packaging (MAP) technology has been commercially viable since the 1970s. Currently, MAP is extensively used worldwide to preserve the quality and extend the shelf-life of whole fresh fruits and vegetables, but is also increasingly used to extend the shelf-life of minimally processed fresh fruit and vegetables. This review discusses new processes and technologies that can be used to improve quality preservation and consumer acceptability of minimally processed produce where high respiration rates and challenging degradation processes operate. New packaging innovations are enabling producers and retailers to further maintain quality for longer. Innovative approaches to extend shelf-life include active MAP with differentially permeable films, films that incorporate antimicrobial properties, edible coatings that confer barriers properties, and the use of non-traditional gases to modify respiration. Intelligent packaging using integrated sensor technologies that can indicate maturity, ripeness, respiration rate and spoilage are also appearing. This review demonstrates that preservation technologies and associated packaging developments that can be combined with modified atmosphere are constantly evolving technology platforms. Adoption of combinations of technology improvements will be critical in responding to commercial trends towards more minimally processed fresh-cut and ready-to-eat fruit and vegetable products, which require specialized packaging solutions.     

包装与贮藏温度对蚕豆采后品质的影响

为明确适宜于鲜食蚕豆采后贮藏的温度与自发气调包装材料,以无保鲜膜包装的蚕豆为对照,研究了(1.0±0.5)℃下聚乙烯(PE)、聚氯乙烯(PVC)、微孔(W)3种保鲜膜包装和(5±1)℃PE保鲜膜包装对蚕豆硬度、色泽、水分含量等品质指标的影响。结果表明,(1.0±0.5)℃下采用PVC保鲜膜包装的蚕豆品质优于其它处理,蚕豆贮藏28d,仍保持较好品质。     

不同超高压处理压力对哈密瓜汁香气的影响

采用固相微萃取方法对不同超高压处理的哈密瓜汁的香气进行富集 ,并经GC MS联机检索分析 ,发现超高压处理对哈密瓜汁中的酯类、醇类、醛类和酮类都有影响 ,其中超高压处理哈密瓜汁的酯类减少了 5种且峰面积减少了约 10 % ,而醛类和酮类增加。 5 0 0MPa/2 0min处理的哈密瓜汁与 40 0MPa/2 0min处理的哈密瓜汁相比 ,酯的种类和峰面积变化不大 ,酮的种类没有变化 ,但增加了 3种不饱和醛。 2种超高压条件处理的哈密瓜汁酯类的特征香气成分未变 ,但醇类和醛类的特征香气成分变化较大。感官评定表明 :超高压处理的哈密瓜汁的香气减弱 ,青鲜气增强 ,这与哈密瓜汁香气成分检测的结果相符合。     

Shelf life of fresh-cut Cime di rapa (Brassica rapa L.) as affected by packaging

In this work, the effectiveness of different packaging in prolonging the shelf life of fresh-cut Cime di rapa (Brassica rapa L.) was addressed. Two subsequent experimental trials were run to investigate first the ability of different packaging materials (an oriented polypropylene, a blend of biodegradable polyesters and a nylon/polyethylene multilayer) in delaying the quality loss and then to assess the efficacy of modified atmosphere packaging (MAP). Two different combinations of gas were investigated, oxygen 10%, carbon dioxide 2% and nitrogen 88%, noted as MAP1 and oxygen 8%, carbon dioxide 2% and nitrogen 90%, noted as MAP2. Headspace gas concentration, weight loss, spoilage microbial growth, pH and sensorial quality were monitored in both sets of experiments. The results demonstrated that the best performances under ordinary atmosphere were recorded with the oriented polypropylene-based film, justifying the choice of this polymeric material in the second set-up. The tested MAPs exerted somewhat different results on product quality: the samples packaged under MAP1 recorded a shelf life of 14 days limited by visible moulds, whereas, fresh-cut leaves sealed under MAP2 highlighted a shelf life less than 9 days, due to a high proliferation of total mesophilic bacteria.     

A study of seeds of musk melon (Cucumis melo L.): A lesser known source of edible oil

The oil content and oil characteristics of seeds of 91 accessions of musk melon (Cucumis melo), including two allied species collected from different parts of the world, have been studied to assess their variability. Oil content (on a whole seed basis) ranged from 12.5 to 39.1% and iodine values from 106.0 to 124.1. Gas liquid chromatographic analysis showed that only linoleic, oleic, palmitic and stearic acids were present. Unsaturated fatty acids constituted 64.6–88.2% of the total fatty acids present. The proportion of kernel in the seeds of different accessions, varied from 25.0 to 74.1% and contributed significantly to the total oil content of the whole seed. A similar relationship existed in the case of the 100-seed weight.     

Effect of vacuum packaging on shelf-life extension of cooked and peeled harpiosquillid mantis shrimp (Harpiosquilla raphidea) during refrigerated storage

Effects of vacuum packaging (VP) on quality changes of cooked and peeled harpiosquillid mantis shrimp (HMS) during storage at 4 °C of 15 days were investigated. VP inhibited bacterial growth as ascertained by the lower rate of increases in total viable and psychrotrophic bacteria counts as well as other pathogenic and spoilage bacteria counts. VP samples had lower total volatile base and trimethylamine contents as compared to the sample packed in air (AP). Clostridium perfringens was undetectable in both samples. During storage, VP samples possessed lower pH than AP counterpart. Exudate and TCA-soluble peptide (TSP) contents of sample increased during the storage, regardless of packaging atmospheres. Fatty acid (FA) content, especially PUFA and MUFA, was decreased after 9 and 15 days of storage for AP and VP samples, respectively. The cooked and peeled HMS contained 32 volatile organic compounds, consisting of several aldehydes and alcohols. Carnobacterium and Pseudomonas were mainly involved in spoilage in samples as confirmed by next generation sequencing.     

Effect of packaging on shelf-life of minimally processed Bok Choy (Brassica chinensis L.)

Different methods of packaging were investigated for their effectiveness in inhibiting quality deterioration of minimally processed Bok Choy (Brassica chinensis L.). Modified atmosphere packaging (MAP) flushed with 5% O₂ and 2% CO₂ resulted in a reduction of respiration rate and ion leakage of minimally processed Bok Choy stored at 10 °C. The chlorophyll content and F_v/F_m value of minimally processed Bok Choy in MAP decreased much slowly than those of Bok Choy sealed directly in polyethylene (PE) bag or in perforated oriented polypropylene (POPP) bag. Weight loss of Bok Choy in MAP and sealed directly in PE were only 1.3%, while that in POPP reached a high value of 11% during the storage of 10 days. The shelf-life of minimally processed Bok Choy in MAP, sealed directly in PE and in POPP bag at 10 °C were 10, 6 and 4 days, respectively, according to the sensory quality evaluation.