[Effect of the position of the container in the retention of nutrients in food models heated by natural convection]. / Efecto de la posicíon del envase en la retención de nutrientes en modelos alimentarios calentados por convección natural.

The existence of statistically significant differences in the nutrient retention of products heated by natural convection in cylindrical containers of equal size when thermally processed in vertical and horizontal position was studied. The thiamine retention was found to be significantly greater for containers placed in vertical position. A modification to the model proposed by Barreiro (4) for the prediction of nutrient retention during thermal processing of vertically placed canned model systems heated by natural convection was also developed to adapt it to containers processed in a horizontal position. To achieve this goal, an equivalent characteristic length was found for the vertically placed containers, and several changes were introduced. The modified model was then evaluated through ten experiments with different thermal processing parameters. The theoretical thiamine retention values predicted by the model wee compared with the experimental retention. In all cases they were within the 99% confidence interval of the experimental values. This demonstrated that the modified model can accurately predict nutrient retention during thermal processing of products packed in cylindrical containers, and placed in horizontal position.

[Nutritional optimization of thermal processing of canned food]. / Optimización nutricional del procesamiento térmico de alimentos enlatados.

The model developed by Barreiro, Salas and Herrera (7) for the prediction of nutrient losses during the thermal processing of conduction heated foods was used in this work to optimize the thermal processing, maximizing nutrient retention in processes with equivalent sterilization values. The processes were stimulated in a digital computer (taking pea purée canned in cans 307 x 409 as the product analyzed). Aall of the processes had equivalent sterilization values with respect to Clostridium botulinum. The thiamine retention associated with each process was calculated by the model of Barreiro, Salas and Herrera (7). The maximum fraction of thiamine retained was of 0.688 for a process at 114.2 degrees C (237.5 degrees F) for 95 minutes. Also, the possibility of the existence of a can with optimum dimensions for maximum thiamine retention, with the same sterilization values, was studied. It was found that this optimum, with the same does not exist; on the contrary, the retention was at a minimum when the diameter approaches infinite and the height zero, and viceversa. For this reason, from the nutrient retention point of view, it is better to process the product in flat or slender cans for a given sterilization value.