The second mechanism that contributes to loss of fruit firm-ness is related to water loss by water vapour transmission that causes loss in cell turgor (Garcia and Barret, 2002). Even though carrageenan provides only low protection against water transmis-sion, it can provide temporary protection against moisture loss by absorbing water and thus act as a ‘sacrificing’ agent instead of a barrier (Pavlath and Orts, 2009). Increase in carrageenan concentra-tions made it possible to form a thick coating layer around the fruit surface that was able to reduce moisture loss until the carrageenan coating itself was dehydrated. Dehydration of the thick carrageenan coating layer instead of the fruit resulted in maintenance of accept-able papaya firmness longer. Application of carrageenan-based coatings on cut grapefruit halves served this function and it was able to provide less shrinkage, leakage or deterioration in taste after two weeks storage at 4 ◦ C (Bryan, 1972).
The second component of the coating, glycerol, showed no sig-nificant (p > 0.1) effect on changes in papaya firmness. However, the term was still kept in the final reduced model since its quadratic effect was positively significant (p < 0.1).