Study On Preparation And Preservation Of Preserved Mango With Medium Moisture

Mango(Mangifera indica Linn.)is one of the famous fruits grown in tropical and subtropical regions.Mango is deeply loved by consumers for its unique flavor.In recent years,with the continuous increase of mango planting area,the output has increased year by year,and the processing of mango has also been paid more and more attention.The preserved mango is one of the most traditional and most popular products.However,the existing dried mangoes generally have the problems of low moisture content,hard taste,high sugar content,and inability to meet consumers’health needs.In this paper,fresh Yumang was used as raw material to research and develop preserved mango with medium moisture.By exploring the aspects of color protection,water retention and reducing water activity,we hope to ensure that the product has a higher moisture content and improve the taste of the original product while maintaining the product’s low water activity without affecting the shelf life.This study can provide theoretical basis and data support for the industrial production of preserved mango with medium moisture.The main research contents and conclusions are as follows:1.The characteristics of raw materials with different maturity and color protection process were studied.The effects of maturity on the basic compositions,texture and color of the raw materials were compared and it is determined that 70%～80%ripeness of Yumang is more suitable for the processing of preserved fruit.The relative enzyme activity of polyphenol oxidase and peroxidase and color difference were used as indicators to study the effect of different blanching temperature and time on relative enzyme activity.Steam blanching for 1.5min could passivate most of the polyphenol oxidase and peroxidase and brighten color.Composite color protection agent(0.2%sodium chloride+0.2%sodium ascorbate+0.5%citric acid)for 3h at room temperature could be significantly different from other groups(p<0.05),which is conducive to subsequent processing.2.The effect of sugar alcohol system on osmotic dehydration of preserved mango was studied.First,the effects of different mass fractions of sugar alcohols(xylitol,erythritol,maltitol),different penetration temperatures and different penetration times on the solids increase rate and water loss rate of mango slices were investigated.Results showed that under the conditions of temperature 45~oC and time 6 h,the water loss rate and solids increase rate of mango slices were higher.The compound sugar alcohol(erythritol:maltitol=1:1)gradient impregnated dried mango had a higher sensory score.At the same time,it can be seen from the low-field NMR that the composite sugar alcohol treatment promoted the water distribution than the single sugar alcohol treatment,and the relaxation time was the smallest,indicating that the water in the system was more stable.Furthermore,the use of three water activity reducing agents(glycerol,propylene glycol,sodium lactate)could reduce the water activity of the product,7%glycerol could reduce the water activity to about 0.65.3.The effects of drying conditions on moisture ratio,texture and color difference were studied.The results show that the drying temperature and intermittent time could promote the drying moisture ratio and drying rate of mango.The higher temperature and longer intermittent time brought the faster moisture ratio drops and the greater drying rate.Under the process conditions of 55~oC(intermittent 4 h),the moisture ratio dropped the fastest and the drying rate is the highest.It took about 9.5 h to dry to the target moisture content.Page model was the best mathematical model to simulate the characteristics of mango during hot air drying.In addition,the brightness of mango was better,the color was yellower,the total acid content was low,and the quality of dried mango was better.Meanwhile,the moisture content and water activity of the product were 23.36%and 0.65.The moisture content of the dried mangoes of the three packaging methods(ordinary,vacuum,nitrogen-filled packaging)decreased slowly during the 12 week storage period,but there was no significant change in water activity and pH(p>0.05),and the total viable counts was within the specified standard range.