Study On Effects Of Plant Extracts On Navel Orange Preservation And Development Of Citrus Composite Preservating Coatings

Citrus industry is the largest fruit industry in the world due to the cultivation area and production, and China is the major player in citrus market. Thereby the development of citrus production plays an important role in economy and social development in China. In recent years, extensive research has investigated the potential application of safe and eco-friendly technology in citrus preservation. But only a little achievements were gained for a series of problems on methods and ways. The overall objective of this study were to prepare botanical citrus preservatives with natural derived antimicrobial agents from plant origin, which may be a viable alternative to chemical and synthetic fungicides. Some conclusions were drawn as following:1. Four plant extracts extracted with different solvents showed significantly different inhibitory effects on Penicillium italicum and P. digitatum, and the acetone extract showed the highest inhibitory activity. Concerned about cost and safety, we chose95%ethanol as extract solvent.2. The four plant extracts can reduce the decay incidence and weight loss of navel orange during storage, and maintain better overall quality and nutrients, among which clove extract is the best.3. The four plant extracts can inhibit respiration intensity of navel orange, reduce the accumulation of MDA, improve SOD and POD activity, thereby delayed senescence of fruits. Meanwhile, all treatments improved activities of PPO, CHT and PAL. Clove extract showed better effects.4. The effect of clove extract on navel orange preservation was as good as chitosan and salicylic acid.5. Select the clove extract as fungicide to develop composite coatings for navel orange, nanfeng mandarin and xinyu mandarin by orthogonal test. The composite coating formulas were as follows:Navel orange:2.0%sodium alginate,300mg/L citric acid and50mg/mL clove extract.Nanfeng mandarin:1.5%CMC,700mg/L citric acid,50mg/mL clove extract and1.0%sucrose esters.Xinyu mandarin:1.0%CMC,700mg/L citric acid,50mg/mL clove extract,1.0%sucrose esters and1.0%calcium propionate.