Critical factors for shelf life prediction of commercial fruit product

English. The study was carried out to identify critical factors for processed fruit shelf life in Tetra Recart packages. To investigate the importance of package volume and headspace volume, vitamin C was chosen to be the indicator. Oxygen in headspace, headspace volume, dissolved oxygen in product, oxygen transmission rate (OTR) and the concentration of vitamin C along storage time were measured to understand the mechanism. The results showed that the degradation of vitamin C is faster and more anaerobic degradation happened in large packages. All three sources of oxygen; dissolved oxygen, oxygen in headspace, oxygen permeated through package, which are decided by headspace volume and package volume, have significant influence on the degradation. Vitamin C was also investigated to see if there was any correlation between the degradation of vitamin C and browning of fruit. Storage tests under different temperatures with different package sizes and initial vitamin C concentrations were conducted to identify the best predictor variable for browning reaction. The a value turned out to be a good indicator and the a value -3 might be the threshold of slight browning. The concentration of vitamin C might also be related to the level of browning. The data extraction and analysis by stepwise regression and ordinal logistic regression were implemented to identify variables that may have the main influence on shelf life. The results accentuate that higher vitamin C concentration, lower heat treatment temperature, longer heat treatment time and lower blanching temperature can contribute to longer shelf life.

English. In a complex product system, a structured method is needed to predict the shelf life, taking all parameters during processing and storage into consideration. The influence of headspace volume, package volume and vitamin C concentration were investigated.