EFFECT OF SOME ENVIRONMENTALLY SAFE TREATMENTS ON STORABILITY AND QUALITY APPEARANCE OF EARLY SWEET GRAPES

Abstract

The effect of two environmentally safe postharvest covered withpotassium silicate (PS) and Gum Arabic (GA) with three wrapped materials, heat shrink film (SH), perforated polyethylene (PPE) bags 40 mu and perforated polyethylene (PPE) bags 80 muon Early sweet grape and stored during 28 days at 0oC or 7oC, relative humidity (90 – 95 %) and after then in marketing temperature in 2013 and 2014 seasons, data reveal that, clusters grapes were dipped in potassium silicate (PS) or in Gum Arabic (GA) and wrapped with heat shrink film (SH) were had the lowest significant percentages of fruit weight loss, decay, shatter and total lose berries percentages these due to increasing in bunch freshness. Average berry firmness and adherence strength decreased as the storage period increased reaching its lowest values at the end of storage in both storage degrees in two seasons,potassium silicate andGum Arabic with heat shrinkreflected the highest berry firmness and adherence strength in this respect during the different periods of storage in two seasons of study. The highest percentages were suggested on weight loss, decay, shatter and discarded berries when clusters dipped in Gum Arabic and wrapped byperforated polyethylene (PPE) bags 80 mu, it was worse than untreated treatment (control) and that due to unacceptable clusters in marketing All privies physical properties were discussed in marketing temperature at (25oC) and found the same liner. When tested effect of treatments on chemical properties such as T.S.S, acidity, TSS / acid ratio found that gradually increased and acidity decreased with extend of storage period during two seasons. On the end of storage days, the untreated clusters and treated clusters with potassium silicate and Gum Arabic plus profited polyethylene 40 and 80 mu give the lowest values of T.S.S without significant different between them. Total acidity in berry juice tended to fluctuate, but some increment was found as a storage period prolonged till 28 days of two cold storagestudded (0oC or 7oC). Thus, all treatments produced a lower acidity in berry juice compared with the control after 28 days of cold storage. Gum Arabic with profited polyethylene in 80 mu (GA + PPE 80 mu) treatment gave the lowest values in T.S.S /acid ratio followed by Gum Arabic with profited polyethylene in 40 mu (GA + PPE 40 mu), potassium silicate with profited polyethylene in 40 mu (PS + PPE 40 mu) and potassium silicate with profited polyethylene 80 mu (PS + PPE 80 mu), potassium silicate with heat shrink (PS + SH)to reach the highest value to Gum Arabic with heat shrink (GA + SH) as compared with the control treatment. Dipping clusters inGum Arabic (GA) or potassium silicate (PS) and wrapped by shrink film (SH) tend to have the effective role in reducing the rate ofrespiration of grape clusters.The same liner were found when tested effect of treatment on marketing period after cold storage. It can conclusion that the best treatment record for dipping clusters in potassium silicate and wrapped by heat shrink film Key words: Early sweet grapes, Gum Arabic, Potassium silicate, Modified atmosphere packing (MAP), Heat shrinkable, Cold storage.