PAPAYA PUREE

Visual Colour of Papaya Puree and Texture of Papaya Puree after Heat Treatment

Visual Colour of Papaya Puree and Texture of Papaya Puree after Heat Treatment

6. DISCUSSION

6.1 cold spot

Thermal processing is used to producing safe and shelf- stable food. The cold spot will generate by retort thermal processing. The cold spot is the coldest point in pouch, which takes the longest time to sterilize the product. Cage retort is used to eliminates cold spots and reduce processing time as the retort pouch is heater up faster and more evenly (Ali et al, 2006). Ali et al (2006) indicated the nutrition qualities of thermal processed food products and sensory of food product in less heat processing time is better than longer processing time. Ali et al (2006) also indicatedrotary thermal processing has more advantage than stationary thermal processing because it is mainly for a high viscosity medium as it reduced sterilization time by approximately 50%. Therefore, it can indicated that rotation of cadge of the retort has affirmative effect for on heat penetration in retort pouches during heat processing. Therefore, control of the retort processing can be accurate prediction of the product cold spot temperature in response to dynamic retort temperature profile.

6.2 Relationship between heat treatment and visual colour change

This was observed while we were conducting the experiment. The higher the temperature was the high rate was seen in case of the visual colour change. Three samples were used in the experiment and all the three were tested on different temperatures (1210C, 1160C, and 1110C). L is positive and represents brightness, a greater than 0 represents red component, a less than 0 represents green component, b greater than 0 represents yellow and b less than 0 represents blue component. The visual colour readings for the papaya puree before the heat treatment was 98.10,-6.55, 10.37 corresponding to the L, a, b values which was the control sample in the study. After the heat treatment at 1210C, 1160C, 111 0C, the visual colour was changed that can be inferred by the decrease in the readings for L, a, b values (see Table 4).

Sample

Control

1210C

1160C

1110C

Sample1

L

98.10

93.59

114.95

113.96

a

-6.55

-3.99

-8.59

-7.98

b

10.37

16.63

38.89

7.01

Sample2

L

99.20

99.08

112.18

106.59

a

-7.84

-3.17

-17.04

-7.13

b

12.31

17.37

34.70

23.98

Sample3

L

101.47

96.34

117.25

103.97

a

-8.60

-5.77

-18.57

-11.83

b

13.68

12.39

46.64

16.78

At temperature 1210C, for sample 1, the L value (93.59) infers that the visual colour of the puree was less bright as the value was decreasing or moving towards 0. The value for a (-3.99) was shifting to a positive number which indicated that the colour of the puree was shifting from green to red in colour. The increase in the b value (16.63) suggests that puree was moving toward yellow colour. Similar patterns were observed for sample 2 and sample 3 in comparison to the control sample. At temperature 1160C, for sample 1, the L value (114.95) infers that the visual colour of the puree was brighter as the value was increasing or moving away from 0. The value for a (-8.59) was shifting to negative value which indicates that the colour of the puree was shifting to green ...