MIXED MODEL APPLIED TO ANALYZE LYOPHILIZATION PROCESS IN MEAT

DELFINO, HUGO; FILIPPINI, OLGA SUSANA; VALERIA MESSINA; ANA MARÍA SANCHO

Florencia

Congreso; Internarional Biometric Congress; 2014

IBC

It is well known that processes may affect the quality of a product. Indeed, various changes in physical, chemical and/or biological characteristics of foodstuffs may occur during processing, storage and distribution. During the latter half of the twentieth century, the latest advances in preserving, has been freeze-drying. The popularity of freeze-drying is based on some well-known advantages compared to competitive processes: sample stability at room temperature, the easy reconstitution by the addition of water, the defined porous product structure, the reduction in weight, and the possibility of easy sterile handling. The aim of the present research is to study changes in color and water activity in round steak submitted to freeze-drying. In first place, in order to optimize the lyophilization process, samples of Semitendinous muscle (ST) were randomized in four trays to evaluate differences among color and water activity. ST was used due that it is considered a muscle that is heterogeneous and it has a regular intra-muscular pattern of muscle fibre trials along the lengths. For analysis, samples were cut with a cork-bore to a cylindrical form with 13 mm diameter and approximately 3 cm in height. Each circular (1.3 cm diameter) sample was sliced in 6 units of 1mm of thickness using a knife. A Mixed Model was applied to analyze color parameters L*, a* and b* among treatment (cooked, lyophilized and rehydrated). Where Yijk is one of the response variable for color (L*, a* and b*); μ is the grand mean value; αi= effect of A factor (Treatment); cj(i)= random effect; еj(ik)= random effect of the error; with i=1,2,...a; j=1,2,...b; k=1,2,?n . Data showed that treatment applied was statistically significant (p0.05), showing that the process was equal among /do not depend on the trays of the equipment. Water activity was analyzed using One way ANOVA, where treatment was applied in four levels. Lightness (L*) values were similar for cooked and lyophilized, but different for rehydrated. a* values were different for lyophilized , rehydrated and cooked samples. On the other hand b* values were similar for cooked and rehydrated samples but different for lyophilized.This is a first stage; our intention is to applied response surface methodology