Study On Storage Quality Evaluation And Packaging Fresh-keeping Technology Of Luli Apple

Mid-early ripening apple varieties can enrich the fruit market and make up for the blank period before the ripening of late ripening apples,thus they are an important part of the diversification of apple variety.The study on storage characteristics of mid-early ripening apples can clarify the quality changes during storage to ensure the market value,and help to further improve the technical system of apple storage and preservation.’Luli’and’Luyan’are new varieties of mid-early ripening apples selected by Shandong Institute of Pomology by using’Gala’and’Tengmu No.1’.Their cultivation area is gradually expanding,but the quality and physiological changes during storage have not been reported until now.In this study,’Gala’apple as control,’Luli’and’Luyan’apples as research objects are used to explore their storage characteristics and fresh-keeping technology in order to provide reference for the storage and processing of mid-early ripening apples.The main results are as follows:（1）In terms of fruit quality,compared with’Gala’and’Luyan’,’Luli’apple had the highest soluble solids content,the highest a*value of pericarp,the highest content of total phenolics,total flavonoids and DPPH free radical scavenging rate.For single phenol,the content of chlorogenic acid was the highest in’Gala’and’Luli’apple pulp,followed by epicatechin,catechin and caffeic acid,while epicatechin was the highest in’Luyan’pulp.The main phenolics in pericarp were hyperoside and epicatechin,followed by catechin,chlorogenic acid and ferulic acid.For the aroma components,aldehydes,alcohols and esters were the main aroma components in the two varieties.Among them,3-methyl-1-butanol,3-methyl-2-butenol,nonanal,2-amino-6-methylbenzoic acid and 1-methyl dibenzofuran were only detected in’Luli’apple.Correlation analysis showed that there was an extremely significant negative correlation between fruit firmness and a*value,and an extremely significant positive correlation between soluble solids,total phenolics,total flavonoids,chlorogenic acid and the scavenging rate of DPPH free radicals.（2）With the increase of maturity,fruit firmness,total acid and L*value decreased,soluble solids and a*value increased.And the content of most single phenol increased significantly,but changed obviously based on the difference of varieties.The chlorogenic acid and hyperoside in’Luli’apple pulp increased,while the caffeic acid and catechin decreased.In pericarp,the hyperoside,protocatechuic acid,ferulic acid and chlorogenic acid increased significantly,while the catechin decreased significantly.（3）During storage at 4℃,the firmness,soluble solids,pericarp L*value and DPPH free radical scavenging rate of’Gala’and’Luli’all showed a downward trend.Compared with’Gala’,’Luli’had lower activities of polyphenol oxidase and lipoxygenase and higher contents of total phenolics,total flavonoids and chlorogenic acid during low temperature storage.In terms of aroma components,the ester content of’Gala’and’Luli’showed an upward trend during storage and shelf life,and the content of aldehydes decreased at first and then increased.However,the alcohols in’Luli’increased during storage and decreased during shelf life,while’Gala’showed an upward trend all the time.During the storage at 0℃,it could be stored for 210 days,and the content of soluble solids and total acid of’Luli’were higher than those of’Gala’,but some fruits suffered quality deterioration due to long-term storage.Moreover,1-MCP treatment helped to maintain the texture and nutritional quality of’Luli’and’Gala’during storage at 0℃.（4）From the perspective of respiration,with the increase of temperature and time,the concentration of oxygen in the box decreased and the concentration of carbon dioxide increased.Taking temperature and time as independent variables and gas components as dependent variables,the respiration regression equation of’Luli’apple was obtained:Y（O₂）=23.84187-0.40107 X₁-0.06964 X₂;Y（CO₂）=-2.71490+0.35526 X₁+0.05510 X₂.For the fresh-keeping of’Luli’apple,the non-hole packaging helped to delay the decrease of fruit firmness,but the perforated packaging maintained a high content of soluble solids.After storage and shelf life,the total phenolics content and antioxidant capacity of apples packaged with 13.5μm combined with 1 mm hole and 25μm combined with 1 mm hole were higher.