Effects of Cold Chain Break on Quality of Summer Squash and Lettuce UNIVERSITY OF FLORIDA HORTICULTURAL SCIENCES TIAN GONG

Transcription

1 Effects of Cold Chain Break on Quality of Summer Squash and Lettuce UNIVERSITY OF FLORIDA HORTICULTURAL SCIENCES TIAN GONG

2 Cold chain 1 Introduction a temperature-controlled supply chain. starts from products harvest. Any break in the cold chain can cause resume of ripening process. loss of quality or total loss of the product. The longer the length of the break and the higher the peak temperatures reached, the more severe the reduction in quality. Cold chain breaks are additive in nature. 2

3 Lettuce (Lactuca sativa) One of the most popular ingredients used worldwide in fresh salads. Providing insoluble fiber, folates, pyridoxine, riboflavin, thiamin, vitamins A and C, calcium, potassium, iron, etc. Highly perishable because of its high mechanical and physiological fragility. 3

4 Summer Squash (Curcubita moschata) Originated from central area of Mexico. Non-climacteric fruit. Picked in immature stage, before complete seed development and peel hardening. Highly susceptible to dehydration, wounding and decay. Extensive postharvest deterioration usually results from softening and rind yellowing. 4

5 2 Objective Determine effects of cold chain break on storage of summer squash and lettuce 5

6 3 Material and Methods Lettuce and Summer squash Harvested on October, 12 th. Washed in cool water and transported back to lab.

7 Experiment design Three treatments: Non-break (control) Delay cooling of 24 h at 20 /68 Cold chain break of 8 h at 20 /68 3 replications, 1 summer squash per replication. 3 replications, 2 lettuce heads per replication.

8 temperature ( ) Control 25 Control treatment hours Summer Squash Lettuce

9 temperature ( ) Delay cooling 25 Delay cooling of 24 h at 20 / treatment hours Summer Squash Lettuce

10 temperature ( ) Cold chain break treatment 25 Cold chain break of 8 h at 20 / treatment hours Summer Squash Lettuce

11 Indices Water loss Water loss was measured at 0, 24, 94, 182, 218, 254 h after harvest for both lettuce and summer squash. Wi: initial weight, Wf: weight at the specified time 11

12 Firmness Measured at two opposite points on equator of summer squash. Using texture analyzer machine (TA-HD plus 5221, UK ). Using a plate of 50 mm diameter. 4 mm distance and 2 mm/s testing speed. Expressed as N. Measured at the same time as water loss. 12

13 Color change Summer squash: at two opposite points on the equator. Lettuce: two points in the upper part of the outmost two leaves. Using chroma meter (CR-400 Japan). Measured at the same time as water loss. 13

14 Statistical analysing Analyzed by ANOVA (SPSS 24). Duncan s multiple range test was performed at p = 0.05 to separate treatment means within each measured parameter. 14

15 3 Results Lettuce Water loss water loss at 254 h Control Delay cooling Cold chain break Decreased in all treatments during storage No significant difference between treatments at 254 h (p=0.269)

16 L value Color change of lettuce Lettuce L value L value at 254 h Delay cooling Cold chain break Control Treatment days 0 Control Delay cooling Cold chain break Increased in all treatments No significant difference between treatments at 254 h (p=0.113)

17 C* value Color change of lettuce Lettuce C* value C* value at 254 h Delay cooling Cold chain break Control Treatment days 10 0 Control Delay cooling Cold chain break Remained stable during storage No significant difference between treatments at 254 h (p=0.116)

18 h value Color change of lettuce Lettuce h value Delay cooling Cold chain break Control Treatment days h value at 254 h Control Delay cooling Cold chain break Decreased significantly in delay cooling and control and decreased in cold chain break No significant difference between treatments at 254 h (p=0.347)

19 0 h Control Delay cooling Cold chain break

20 24 h Control Delay cooling

21 86 h Control Cold chain break

22 94 h Control Cold chain break

23 182 h Control Delay cooling Cold chain break

24 Firmness at 254 h Control Delay cooling Cold chain break Summer squash Water loss at 254 h Control Delay cooling Cold chain break No significant difference in water loss and firmness between treatments at 254 h (p=0.424, p=0.299)

25 L Value Color change of Summer squash Summer squash L value Delay cooling Cold chain break Control Treatment days Remained stable during storage No significant difference between treatments at 254 h (p=0.115) L value at 254 h Control Delay cooling Cold chain break

26 C* Value Color change of Summer squash Summer squash C* value Delay cooling Cold chain break Control Treatment days C* value at 254 h Control Delay cooling Cold chain break Remained stable during storage No significant difference between treatments at 254 h (p=0.168)

27 h Value Color change of Summer squash Summer squash h value Delay cooling Cold chain break Control 100 h value Treatment days Control Delay cooling Cold chain break Remained stable during storage No significant difference between treatments at 254 h (p=0.526)

28 Control 0 h 24 h DC CCB C DC C 86 h 94 h C CCB CCB C 182 h DC CCB C DC: Delay cooling CCB: Cold chain break C: Control

29 Time lapse: from 182 h to 154 h

30 4 Discussion The results were not as expected. According to P Colás-Medà et al. (2016) fresh-cut pears stored under cold chain break conditions (5 d at 8 ) led to more dissatisfaction (44 %) compared with those maintained at 4 C over the entire shelf life (25 %). Probably because either the cold chain break duration is not long enough or the observation duration is not long enough to see great changes. As lettuce has been washed after harvest and wrapped in plastic bags to prevent water loss, treatments did not greatly affect its water loss.

31 5 Conclusion Cold chain break did not cause significant damage to lettuce in regard of water loss within 10 days. Lettuce paled and became yellow during 10 days storage in all the treatments. Cold chain break did not cause significant damage to summer squash in regard of water loss and firmness within 10 days. Cold chain break did not have significant effects on color of summer squash.

32 Thank you!