WORK PACKAGE 6. COATING FORMULATION. 10 % Kaffirin Ethanol as solvent Plasticiser mixture (1:1:1) Polyethylene Glycol Lactic Acid Glycerol Relaxation Time –16 hrs. OBJECTIVES OF THE STUDY. To determine the effect of 10 % Kaffirin coating:. • On the sensory acceptability of litchi.
To determine the effect of 10 % Kaffirin coating:
• On the sensory acceptability of litchi
• On the post-harvest response & shelf-life
of litchi over the distribution chain
Cleaned, freshly harvested litchi
Dipped with stalk in coating for 10 secs
Allowed to air dry for 1 hour
Stalk clipped off and litchi placed on trays or plastic bag
Packing favoured mould growth
Day 9, Ambient Temp
White deposit still present
Day 6, 13oC
Bozdemir and Tutas (2003) studied the barrier properties of edible films prepared from polysaccharide polymer (locust bean gum) and various plasticisers (glycerol, propylene glycol, sorbitol, and polyethylene glycol 200) together with hydrophobic modifiers (stearopten and beeswax). They too observed the presence of a white residue and reported that the appearance of a white residue on edible films containing plasticisers has been referred to as “blooming" or blushing" -this occurs when the plasticiser concentration exceeds its compatibility limit in the polymer causing phase separation and physical exclusion of the plasticiser. A similar phenomenon of blooming can have occurred in this study
APPLICATIONS OF COATINGS TO FRUITS AND NUTSINTRODUCTIONThe main aim of the ENVIROPAK project was to improve the quality of southern African export fruits and nuts by extending their shelf-life through application of edible coatings made from sorghum protein, kafirin. These coatings can potentially provide a semi-permeable barrier to gases and water vapour, thereby reducing respiration rate and water loss. Studies have therefore been carried out to determine the effect of selected kafirin coatings on the post-harvest response and shelf-life of litchis, pears and cashew nuts.EXTENDING THE SHELF-LIFE OF EXPORT QUALITY LITCHISDaya GoburdhunUniversity of MauritiusFaculty of AgricultureReduitMauritiusE mail number: firstname.lastname@example.orgFrom a baseline study conducted, the major post harvest problems associated with litchis were identified as rapid peel (pericarp) browning resulting in a loss of the favourable red colour as well as water loss. The effect of a kafirin coating on the post-harvest response and shelf-life of litchis stored under conditions simulating domestic, retail and export conditions were investigated.
Immediately after coating, the litchis appeared red in colour and were glossier than the uncoated litchis (Figure 1). However, after only one day of storage, an unacceptable darkening of the whole peel (pericarp) surface occurred as well as the formation of a white powdery deposit on the peel (Figure 2). It was therefore not surprising that the external colour of the uncoated litchis were preferred to that of the coated litchis by the majority of panelists in a consumer sensory evaluation test.
Although the kafirin coating did not affect the pH, titratable acidity or total solids content of the litchis during storage, it decreased the respiration rate of the litchis stored at 4 °C. . Compared with the uncoated litchis, slight decreases were observed in microbial counts for the coated litchis in terms of aerobic bacteria, coliforms and moulds. However, the kafirin coating did not provide a suitable water vapour barrier, since the use of the coating did not reduce water losses