EFFECT OF CANDELILLA WAX WITH NATURAL ANTIOXIDANTS ON THE SHELF LIFE QUALITY OF FRESH-CUT FRUITS

ABSTRACT

Films formulated with edible natural waxes extracted from Euphorbia antisyphilitica, and additives Aloe vera (4%), ellagic acid (0.01%) and gallic acid (0.01%) were applied to evaluate their effects on the quality of fresh‐cut fruits stored at 5C and at room temperature (21C) for 6 days. The evaluated characteristics were changes in appearance, weight loss, firmness, color, solid content, pH and water activity (A_w). The additives, combined with the natural wax, demonstrated not to cause apparent damage to the fruits. Generally speaking, the films showed better results in comparison with the control. The treatment with A. vera showed the lowest values in weight loss, water migration, A_w, change in pH and firmness. The ellagic acid coating reduced the color change in a greater proportion. The application of these new edible films to fruits extends their shelf life and increases their antioxidant potential, as well as their nutritional quality.

PRACTICAL APPLICATIONS

Edible films elaborated with a natural wax extracted from Euphorbia antisyphilitica complemented with a potent antioxidant ellagic and gallic acids, and Aloe vera extend the shelf life quality and increase the antioxidant potential, as well as the nutritional quality of fresh‐cut fruits and vegetables, giving way to the possibility of producing nutraceutical products in the form of edible biofilms. Potential applications of these films are very attractive because the components are natural and nontoxic, and they are recommended by their low cost, availability and ease of handling. The possibility of using these films on other food products, not necessarily vegetal in origin, could be assayed.

     

ON THE COMPOSITION OF HOP WAX

Hop wax contains free alcohols, free acids, wax esters, hydrocarbons, β-sitosterol and traces of campesterol. The composition of the free alcohols, free acids and wax esters was investigated. Varietal identification of hops based on wax composition is not reliable.     

天然宝石及人工合成宝石中包裹体研究

随着国民经济的发展,矿物材料研究已成为一个重要方向,宝石合成近１０年来取得了不少成绩,如蓝宝石、祖母绿、红宝石、钻石、紫水晶等,合成宝石可以达到以假乱真的地步。因此,给宝石鉴定带来了一定困难。矿物中包裹体的特征可以作为宝石鉴定的一种重要手段,深入研究天然宝石中包裹体的特征可以区分它的产地,因不同地区的某种宝石具不同的成矿物质来源及形成的物理化学条件,故矿物中包裹体相的组分及相比例等特征亦各异;并对     

甘薯纤维提取工艺及应用研究

对利用甘薯渣提取纤维的工艺以及甘薯纤维的理化特性进行研究.结果表明:采用甘薯渣制糖残渣提取纤维为适宜工艺.对甘薯纤维理化特性的测定表明,甘薯纤维是一种优良的食物纤维.甘薯纤维在焙烤食品生产的应用结果表明,为保证产品的质量,其添加量不能过多,在面包和蛋糕中的添加量分别不能超过7%和6%.     

植物性天然香料的提取与应用

综述了植物性天然香料的组成、近年来的提取新枝术及其广泛应用，并探讨了进一步研究的方向．     

脂肪酶的固定化及其水解天然黄油研究

利用吸附法、交联法和包埋法将脂肪酶固定在5种载体上，由吸附法制备的固定化脂肪酶活性最大，用其催化天然黄油的水解反应，短时间内水解率可达到20％左右。且有较高的可操作性，重复利用5次，活性依然保留为原来的96％。     

DETERMINATION OF PARAFFIN WAX AND MINERAL OIL ON FRESH FRUITS AND VEGETABLES BY HIGH TEMPERATURE GAS CHROMATOGRAPHY

Paraffin wax and mineral oil coatings were determined on a large number of domestic and imported fruits and vegetables by high-temperature gas chromatography employing a Dexil 300 liquid phase with temperature programming up to 400°C. The surface coatings were removed from the foods by repeated dipping in chloroform. The chloroform extracts were concentrated and analyzed directly by gas chromatography. Identification of the waxes was made by comparison to known paraffin or mineral oil standards. Paraffin wax or mineral oil were found on squash, turnip, cucumber, sweet potatoes, egg plant, and most citrus fruits.     

天然微生物抗菌防腐剂及其在食品工业上的应用

介绍了微生物防腐剂溶菌酶、乳酸链球菌素、聚赖氨酸、曲酸、纳他霉素的抗菌防腐机理,及其在食品工业中的应用.     

毛蚶中天然牛磺酸的提取及其对果蝇寿命的影响

研究了热水浸提法从毛蚶中提取天然牛磺酸的工艺,确定最佳提取条件为90℃提取2h,上柱液调至pH4～5后进行阳离子树脂交换层析;通过纸层析、熔点测定及其红外图谱对制备样品进行理化性质鉴定,表明得到的天然牛磺酸的纯度较高;通过果蝇寿命实验比较了天然牛磺酸与合成牛磺酸延寿功效的差别,表明天然牛磺酸较合成牛磺酸的延寿效果好.     

EFFECT OF WAX APPLICATION ON THE QUALITY,LYCOPENE CONTENT AND CHILLING INJURY OF TOMATO FRUIT

ABSTRACT

Waxed and nonwaxed mature green tomato fruits were stored at 12C (nonchilled) or 5C (chilled) for 5, 10, 15 and 20 days before being transferred to 22C for 3, 6, 9 and 12 days, were evaluated for weight loss, chemical composition, skin color, chilling injury (CI) index and pigment content. Waxed fruits showed a delay in weight loss, color development and ripening. The sensitivity of tomato fruit to CI was reduced in waxed fruits, which showed a delay in the appearance of symptoms. A delay in chlorophyll degradation and lycopene synthesis was observed as a result of the use of wax and low temperature. Waxing of tomato fruits allowed their storage at temperatures below critical reducing CI sensitivity and maintaining quality giving more time for marketing.

PRACTICAL APPLICATIONS

Nowadays, local tomato producers use wax on fruits as an everyday practice to carry postharvest fungicides and to improve brightness. They store tomato fruits at nonchilling temperature (12C) because lower temperatures would cause chilling injury and irregular ripening. In this way, it is interesting that waxing tomato fruits allow reducing their storage temperature, protecting them from chilling injury and maintaining their quality and correct color change and ripening; thereby producers and sellers have more days to position their fruits with no extra cost.     

冬瓜贮藏过程中PPO、POD和CAT活性及同功酶研究

研究了青皮冬瓜(Benincasa hispida)在贮藏过程中，其保护酶系统中POD和CAT以及PPO活性和同功酶电泳图谱变化。结果发现：腐烂前后冬瓜果肉中PPO活性升高，POD和CAT活性下降。电泳谱带分析发现，腐烂果肉中PPO的Rf0．19、POD的Rf0．17-Rf0．26Rf0．7以及CAT的Rf0．61条带出现了缺失。冬瓜果肉中未能检测到超氧化物歧化酶(SOD)活性。     

EDIBLE COATINGS ON FRESH SQUASH SLICES: EFFECT OF FILM DRYING TEMPERATURE ON THE NUTRITIONAL AND MICROBIOLOGICAL QUALITY

The exposure of foods to the temperature and humidity needed to dry the coatings can have deleterious effects on their quality. A critical analysis of the film drying conditions on quality indexes for butternut squash slices is presented. During the coatings drying, the samples lost significant amounts of weight and ascorbic acid. Only during the drying of the chitosan coating for 100 min at 20C and for 30 min at 50C that the ascorbic acid contents were not significantly reduced. The application of casein and carboxy methyl cellulose coatings did not cause significant reductions in the counts of mesophilic aerobic microorganisms (5.75–6.00 Log CFU/g). Chitosan coated samples presented significant log reductions showing the higher reductions the samples dried for 30 min at 50C (5.02 Log CFU/g). For the preservation of the nutritional and microbiological quality indexes of squash slices, the best coating conditions would be chitosan dried for 30 min at 50C.

PRACTICAL APPLICATIONS

The continuous consumer interest in high quality and food safety, combined with environmental concern, has induced the development and study of new edible coatings that avoid the use of synthetic materials. The edible coatings, formed from Generally Recognized as Safe materials, have the potential to reduce weight loss, respiration rate and improve food appearance and integrity. It is one of the most effective methods to maintain food quality.
Antimicrobial films and coatings have innovated the concept of active packaging and have been developed to reduce, inhibit or delay the growth of microorganisms on the surface of food in contact with the packaged products. In addition, the edible coatings allow the incorporation of food additives with antimicrobial effects that might help reduce microbial spoilage during postharvest.     

THE EFFECT OF COATINGS AND PROCESSING METHODS ON DEHYDRATED PRECOOKED WHOLE PINTO BEANS QUALITY1

Splitting is a major problem in preparing dehydrated precooked beans. To reduce splitting and improve the product quality of precooked pinto beans, three coating treatments and two processing methods were investigated. Beans were blanched, soaked, steam precooked, coated by dipping in a biopolymer solution, and dehydrated in an air-circulating dryer. Coating beans in a 20% dextrin solution (Lo-Dex 5, M100, or K4484) reduced 43–85% of butterflying (severe splitting) of beans. Steam precooking at 121C/30 min with soaking at 22C/12 h yielded less butterflying than steam precooking at 100C/1 h with soaking at 30C/2 h and 82 C/1 h after coating and dehydration (?3% vs 8%). The former resulted in lower firmness after precooking and rehydration of dehydrated beans, whereas the latter gave beans a more mealy texture and better appearance. The rehydration time of dehydrated precooked beans in boiling water to produce an acceptable firmness was 6–9 min, depending on the processing methods. Coating resulted in darker color and slower rehydration of dehydrated beans.     

龙眼活性物质的提取及其抗氧化能力的研究

研究了龙眼中抗氧化活性物质的提取工艺和不同品种龙眼提取液的抗氧化能力.结果表明:在回流提取条件下石硖龙眼的2mL提取液对DPPH·的清除率为52.82%,对·OH的清除率为42.31%;在微波辅助的条件下分别提高为62.45%和54.36%.微波辅助的提取条件下,石硖、大乌圆、玲珑、储良四种龙眼的2mL提取液对DPPH·的清除率分别为62.45%、64.78%、45.13%、59.03%,对·OH的清除率分别为54.36%、55.39%、16.35%、47.14%.龙眼中具有抗氧化能力的物质主要为多酚、黄酮类.     

紫苏中天然抗氧化物质的提取及增效作用的研究

采用不同溶剂,从唇形科植物紫苏茎叶中制得各种提取物,用烘箱法测定它们在色拉油、菜油中的抗氧化性,并与茶多酚、ＶＥ比较。实验表明,体积比为８：２的乙醇与碱水混合物的提取物的得率最高,抗氧化性能优于其它提取物,将此提取物经上柱处理后,其抗氧化性比前者更好,且优于茶多酚,与ＶＥ相近。当达到最佳抗氧化效果时,其最小使用量为０．０７％,柠檬酸对其有很好的增效作用。初步鉴定其活性成分为酚类,黄酮类化合物。