Effect of Different Storage Conditions and Packaging Materials on Safety and Quality of Sudanese Red and White Guava (Psidium Guajava L.) Cultivars for use in Juices Production

Abstract

This study was conducted to evaluate the quality attributes of red and white guava fruit and their juice as affected by storage period, packaging materials and storage temperature. Red and white flesh guava were divided into four groups each one of them was packed in Poly Venial Chloride (PVC) and polyethylene then were stored at room temperature and refrigeration for 7 days. Different analyses for guava samples conducted including microbiological ( total viable bacterial count (TVBC), E. coli, Staphylococcus aureus and Yeast and mould), physicochemical (pH, firmness, and TSS), chemical (moisture, fat, ash, fiber and carbohydrates, phosphorus, potassium and vitamin C) and analysis sensory (color, taste, flavor and overall acceptability). The results on safety revealed that, white flesh guava was higher TVBC (1.35log10cfu/g) than the red one (1.26log10cfu/g). In addition both guava cultivars were yeast and molt positive. However, all guava samples were pathogenic E. coli and Staphylococcus aureus free, indicated safety of the tested fruits. Regarding physicochemical properties and chemical components of guava fruits pH, firmness, ash, fiber, carbohydrate potassium and vitamin C were significantly (P<0.05) affected by the guava cultivars. White guava recorded higher levels of pH, firmness and phosphorous than the red one. Whereas the red cultivar was higher in moisture, fat, ash, potassium and vitamin C in comparson with the white cultivar. During the storage period both guava cultivars packed in PVC reported lower TVBC as compared to those in polyethylene package. In addition, all cultivars were yeast and moulds positive. It worth mentioning that, all guava cultivars in different packaging materials stored at different storage temperatures were E. coli and Staphylococcus aureus free indication safety of fruits after storage, From physicochemical angle, throughout the storage period both guava cultivars packed in PVC were higher in pH, firmness and TSS as compared to polyethylene packed one. Furthermore, chemically, both guava cultivars packed in PVC maintained higher levels of ash, carbohydrate and vitamin C than those packed in polyethylene. However, in both guava cultivars extending the storage period significantly (P<0.05) affected pH, TSS, ash, carbohydrate and vitamin C except for firmness. On the other hand, refrigeration storage for both guava cultivars in different packaging types maintained lower TVBC, better physicochemical and chemical components throughout the storage period. Concerning guava juices, red cultivar initially reported lower TVBC (log10cfu/g) than that juice prepared from white cultivar one (log10cfu/g). However, TVBC increased by extending refrigeration storage of all juices to six days. All juices under study were E.coli and Staphylococcus aureus free but were yeast and moulds positive. Juice from red guava cultivar contained higher levels of total solids, reducing sugar and Vitamin C than the white cultivar. Generally, pH, total solids and vitamin C were decreased by extending the storage period to six days; while reducing sugar was increased. In contrast, there were TVBC and reducing sugar was increased. Sensory evaluation declared that juice from red quava cultivar was more acceptable in term of appearance, taste, flavor and texture than the white cultivar. Therefore, using PVC package at refrigeration temperature is more appropriate for both red and white guava cultivars. Safety (free of pathogenic E.coli and Staphylococcus aureus), better physicochemical properties and chemical quality of guava fruits were maintained throughout the storage period. Juice from red guava cultivars was accepted by panelists. Moreover, it is rich in total solids, reducing sugar and Vitamin C than the white cultivar. Therefore, the results concluded that, PVC is the best packaging materials for guava fruit and ( +4℃) is the best temperature for storage .