Question

Why is HTST better than LTLT? A juice product is needed to be heat processed to achieve 2 log reduction in microbial count. It could be accomplished by heating the juice product either at 65 or 75 C. The D value for bacteria cell death at 65 C is 10 S and z value is 10 C. D value for ascorbic acid degradation at 65 C is 50 s and Z value is 20 C. The heat transfer penetration data at 65 and 75 C is given below. Determine ascorbic acid losses at 65 C and 75 C

65 °C         75 °C

time, temp   time, temp

0 30 °C        0   30 °C

30 50 °C      10 45 °C

60 60 °C      20 61 °C

90 65 °C      30 75 °C

120 40 °C    40 40 °C

Answer 1

HTST: High Temperature short time pasteurization (Foods are heat processed to kill pathogenic bacteria ) technique. This process uses higher heat for lesser time to kill bacteria. For example,milk is pasteuized at 72 degree celsius for 15 seconds.

LTLT: Low Temperature Long time pasteurization technique. This process uses lesser heat for longer time to kill bacteria. For example,milk is pasteuized at 63 degree celsius for 30 minutes.

It is important to note that time and temperature depands upon: 1. the type of food,and 2. the final result one wants to achieve, such as food contents, nutrients, color, texture etc.

HTST is better than LTLT, because of following reasons:

1. This process reduces the time to pasteuize the milk.

2.Utilisation of incoming chilled milk to cool to hot pasteuized milk increases the efficency of pasteuization sysytem (PHE).

3. Smaller amount of heat energy is required to heat the milk to pasteuization temperature.