3.3.3. Firmness
Loss of firmness is one of the main factors limiting quality and the postharvest shelf-life of fruit and vegetables. Strawberries soften during ripening, mainly through degradation of the middle lamella of the cell wall of cortical parenchyma cells (Perkins-Veazie, 1995). Other factors influencing fruit firmness are cell wall strength, cell to cell contact and cellular turgor (Harker et al., 1997). The general trend in firmness changes in strawberry fruit in all treatments stored at 20 °C is shown in Fig. 4. The coating significantly improved firmness of the fruit (Fig. 4). Incorporation of C. laurentii into formulations had a significant positively effect on firmness. Samples coated with alginate containing C. laurentii maintained their firmness during the entire storage period. Furthermore, strawberries coated with SA containing C. laurentii achieved the highest firmness values ( Fig. 4) among these groups. The firmness of fresh strawberries decreased during storage ( Fig. 4), which was similar to the results of Zhang and Quantick (1998). From 2 to 5 d, the firmness value was the lowest among the tested groups at every storage day. The result of the coating significantly controlling loss firmness agrees with the conclusions drawn by Carrilo-Lopez et al. (2000). One of the reasons for the delay in senescence may be the development of an adequate internal micro-atmosphere in the coated fruit. Strawberry metabolism would have slowed down in the micro-atmosphere and the storage life prolonged ( El Ghaouth et al., 1991). Another reason may be that the film prevented the loss of moisture from the fruit.