Total soluble solids

4. IN VITRO AND IN VIVO DISINFECTION AND BIOCONTROL TREATMENTS

5.6 Results and Discussion

5.6.6 Total soluble solids

Table 5.10 Changes in the peel moisture content (%) of Penicillium italicum- inoculated kumquat fruit over a 28-day storage period subjected to different integrated pre-packaging treatments

Treatment Storage Period (Days)

0 7 14 21 28

Chlorinated water 80.4^f 70.2^cd 63.5^bc 53.1^ab 46.5^a

Anolyte water 80.4^f 70.8^cde 66.6^bcd 56.8^abc 40.0^a

Hot water 80.4^f 74.7^ef 69.0^cd 61.3^bc 54.6^ab

Biocontrol (B13) 80.4^f 70.3^cd 64.4^bc 57.1^abc 43.7^a

Chlorinated water + HWT 80.4^f 73.4^def 68.7^cd 64.6^bc 56.3^abc Chlorinated water + B13 80.4^f 71.8^de 67.5^bcd 61.2^bc 46.4^a Chlorinated water + HWT + B13 80.4^f 71.0^cde 68.9^cd 58.3^abc 50.5^ab Anolyte water + HWT 80.4^f 72.4^de 62.8^bc 62.7^bc 53.0^ab Anolyte water + B13 80.4^f 70.9^cde 65.7^bcd 56.3^abc 44.9^a Anolyte water + HWT + B13 80.4^f 72.3^de 68.9^cd 63.3^bc 54.6^ab

HWT + B13 80.4^f 70.5^cde 67.0^bcd 67.3^bcd 52.2^ab

Control 80.4^f 71.7^de 67.1^bcd 57.8^abc 50.8^ab

Significance

Treatment (A) **

Storage Period (B) **

AB **

CV (%) 5.4

NS, *, ** Non-significant or significant at P≤0.05 or P≤0.001, respectively. Means within a column followed by the same letter(s) are not significantly different from each other according to Duncan’s Multiple Range Test (P≤0.05), (n=3). CV, Coefficient of variation; HWT, hot water treatment; +, ‘combined with’.

period from Day 0 to Day 14, compared to days 14 to 28. The TSS of kumquats for individual treatments and the control were higher, compared to those that were exposed to integrated pre-packaging treatments.

Table 5.11 Changes in the total soluble solids (Brix) of Penicillium digitatum- inoculated kumquat fruit over a 28-day storage period subjected to different integrated pre-packaging treatments

Treatment Storage Period (Days)

0 7 14 21 28

Chlorinated water 10.2^a 12.0^ab 14.9^cd 16.0^def 18.5^hi

Anolyte water 10.2^a 12.4^ab 14.3^bcd 15.3^cd 16.3^ef

Hot water 10.2^a 13.4^abc 14.0^bc 15.6^cde 16.3^ef

Biocontrol (B13) 10.2^a 12.0^ab 15.6^cde 15.9^de 16.4^efg Chlorinated water + HWT 10.2^a 13.5^abc 14.5^bcd 16.8^gh 15.8^de Chlorinated water + B13 10.2^a 12.2^ab 13.5^abc 16.4^ef 16.7^fg Chlorinated water + HWT + B13 10.2^a 12.9^abc 13.35^abc 16.5^efg 16.7^fg Anolyte water + HWT 10.2^a 12.1^ab 15.1^cd 16.0^def 16.0^def Anolyte water + B13 10.2^a 10.8^a 14.3^bcd 16.1^def 15.8^de Anolyte water + HWT + B13 10.2^a 9.93^a 14.2^bcd 15.2^cd 15.7^cde

HWT + B13 10.2^a 11.6^ab 13.1^abc 15.2^cd 16.6^efg

Control 10.2^a 11.9^ab 15.6^cde 16.1^ef 17.8^h

Significance

Treatment (A) NS

Storage Period (B) **

AB NS

CV (%) 9.3

NS, *, ** Non-significant or significant at P≤0.05 or P≤0.001, respectively. Means within a column followed by the same letter(s) are not significantly different from each other according to Duncan’s Multiple Range Test (P≤0.05), (n=3). CV, Coefficient of variation; HWT, hot water treatment; +,

‘combined with’.

Table 5.12 depicts the changes in the TSS of P. italicum-inoculated kumquat fruit subjected to different pre-packaging treatments for a 28-day storage period. The treatment and storage period were found to have a highly significant (P≤0.001) effect on the TSS of kumquat fruit. A general increase in the TSS was observed for kumquat fruit under all treatments. Kumquat fruit treated with chlorinated water only and control samples were observed to have highest TSS values of 18.2 Brix and 18.5Brix, respectively.

The two-way interaction between treatment and storage period was found to be highly significant (P≤0.001) with regard to the TSS of kumquat fruit. The least increase in the TSS was found in samples treated with the combination of anolyte water, hot water and biocontrol of 14.8 Brix. The TSS was found to increase more rapidly at the start of the storage period between Days 0 and 7.

Table 5.12 Changes in the total soluble solids (Brix) of Penicillium italicum- inoculated kumquat fruit over a 28-day storage period subjected to different integrated pre-packaging treatments

Treatment Storage Period (Days)

0 7 14 21 28

Chlorinated water 10.7^a 13.5^cd 14.9^de 15.6^ef 18.2^h

Anolyte water 10.7^a 13.1^bcd 13.5^cd 15.1^def 15.9^ef

Hot water 10.7^a 11.7^ab 13.4^bcd 15.4^def 15.7^ef

Biocontrol (B13) 10.7^a 12.8^bc 14.5^cde 15.3^def 17.3^g Chlorinated water + HWT 10.7^a 12.8^bc 13.5^cd 14.5^cde 17.3^g Chlorinated water + B13 10.7^a 13.7^cd 13.8^cd 14.5^cde 16.0^ef Chlorinated water + HWT + B13 10.7^a 12.8^bc 13.4^bcd 14.9^de 16.3^efg Anolyte water + HWT 10.7^a 13.0^bcd 13.3^bcd 13.5^cd 16.3^efg Anolyte water + B13 10.7^a 13.1^bcd 14.0^cde 15.0^def 15.4^def Anolyte water + HWT + B13 10.7^a 12.7^bc 13.1^bcd 14.6^de 14.8^de

HWT + B13 10.7^a 12.7^bc 13.8^cd 15.2^def 16.7^fg

Control 10.7^a 12.8^bc 14.4^cde 15.4^def 18.5^h

Significance

Treatment (A) **

Storage Period (B) **

AB **

CV (%) 5.6

NS, *, ** Non-significant or significant at P≤0.05 or P≤0.001, respectively. Means within a column followed by the same letter(s) are not significantly different from each other according to Duncan’s Multiple Range Test (P≤0.05), (n=3). CV, Coefficient of variation; HWT, hot water treatment; +,

‘combined with’.

An increase in the TSS of citrus fruit have been observed by D’hallewin et al. (1994), Olmo et al. (2000), Rodov et al. (2000) and Ladaniya (2008), which can be attributed to a loss in water after harvest. Therefore, as the fruit matures an increase in the TSS is expected. However; Hong et al. (2007) found that the TSS decreased in Satsuma

plant tissue metabolism. In addition, the degradation of cellulose, hemicellulose and pectin from the cell walls of the fruit segments may release soluble components, which directly increases the TSS (Roongruangsri et al., 2013). D’hallewin et al. (1994) found that the TSS in heat-treated (36C for 72 hours) and UV-treated (24 nm) Avana mandarins were lower, compared to control samples at 7.85, 7.63 and 8.02 Brix, respectively. Hong et al. (2014) found that the combined treatment of hot water, biocontrol and sodium bicarbonate resulted in mandarin fruit with lower TSS values, compared to control samples.

Based on the results it can be stated that the use of integrated treatments are beneficial in reducing the rate of increase of the TSS, which is an indication of a slower maturation rate. The use of anolyte water, hot water and biocontrol have been found to be the most effective treatment in reducing the rate of maturation of kumquat fruit.