Study on the fresh-keeping and packaging technolog

Research on fresh-keeping packaging technology of olive fruit (Part 2)

2 results and discussion

2.1 storage effect of olive fruit packed in PE bags with different thickness

stored at room temperature for 125 days, the good fruit rate of each group of fruits packed in PE bags is significantly higher (P> 0.01) than that of the control group in bulk (all fruits in the control group lose water, shrink, turn dark brown, have no commodity value, and the good fruit rate is 0). However, there was no significant difference in the good fruit rate among the packaging groups (P> 0.05). The good fruit rate of 0.060 mm thick and 0.030 mm thick was higher, 86.87% and 86.60% respectively, while the good fruit rate of 0.015 mm was lower, 75.60% (Table 1). In terms of weight loss rate, the weight loss rate of olive fruit packed in PE bags was significantly lower than that of the bulk control group (P <0.01), which showed that film packaging could effectively inhibit the water loss and weight loss of olive fruit. The weight loss rate of 0.060 mm thick was the lowest, which was 1.20%, significantly lower than that of 0.010, 0.015, 0.040 mm thick packaging groups, but there was no significant difference with 0.030 mm (P> 0.05). From the gas composition in the packaging bag, the CO2 content in the 0.060 mm thick packaging bag is the highest, which is 1.58%, which is significantly higher than that in the other thickness packaging group, and the O2 content is the lowest, which is 19.78%, which is significantly lower than that in the other thickness packaging group, while the CO2 and O2 values in the 0.010--0.040 mm thick packaging group have little difference (Table 1). After tasting, it was found that the fruits of each packaging group had no fermentation taste, and the absence of ethanol was the harm of selling and shutting down internal supporting enterprises. The determination result showed that the ethanol content of fruits in 0.060 mm thick packaging bag was the lowest, 22.0 μ g. G-1 pulp. From the above analysis, it can be seen that the 0.060 mm thick PE film packaging group has the highest fruit yield, the lowest weight loss rate, the best CO2 and O2 values and the lowest ethanol content compared with other thickness packaging groups (Table 1). Therefore, the thickness of PE film bag as the storage and packaging material of olive fruit should be 0.060 mm

Table 1 storage results of Chinese olive fruit packing with variable thickness PE film bags (stored at ambient temperature for 125 days)

table 1 the storage results of Chinese olive fruit packing with variable thickness PE film bags (stored at ambient temperature for 125 days)

film thickness/mm good fruit rate/% weight loss rate/% co2/% o2/% ethanol/μ G · g-1 pulp

0.0100.0150.0300.0400.060ck (bulk) 81.33b b75.60b b86.60b b83.13b b86.87b B0 a 3.14 B b3.33 B b2.27 BC there should be no barge, wrinkles, bubbles and adhesion b3.54 B b1.20 B b66.80 a 0.510.490.520.541.580.03 20.5820.6820.5720.6419.7821.00 27.223.534.831.922.0 ------

note: the numbers in the same column followed by large and small letters indicate that the difference reaches the 1% extremely significant level and the 5% significant level respectively

2.2 storage effect of olive fruit with different packaging materials and packaging methods

different packaging materials and packaging methods have different storage effects on olive fruit (Table 2). Among them, the storage effect of film perforated packaging is good, the highest rate of good fruit is 96.40%, and the lowest rate of weight loss is 0.64%, which is significantly different from the tray + EVA, straw basket + PE packaging treatment group (P <0.05). Tie the bag mouth tightly with PE bag The difference of PE vacuum packaging was not significant (P> 0.05). The storage effect of straw basket + PE packaging was the worst, its good fruit rate was significantly lower than that of other packaging treatment groups (P <0.01), and the weight loss rate was as high as 14.10%. The fruit appearance showed obvious water loss and shrinkage, and the weight loss rate was significantly higher than that of other packaging treatment groups (P <0.01). There was no significant difference in the good fruit rate between PE bags with tight bag mouth, PE vacuum pumping, tray + EVA fresh-keeping film packaging (P> 0.05); The weight loss rate of tray + EVA fresh-keeping film packaging was significantly higher than that of PE bag packaging group (P <0.01) (Table 2). The good fruit rate of perforated film is higher than that of other non perforated packaging groups, because this packaging method can overcome the damage caused by abnormal gas of spontaneous controlled atmosphere storage (MA) of plastic film, such as high CO2 damage caused by different samples and experimental force, and can also inhibit weight loss [9]. The weight loss rate of straw basket + PE packaging was significantly higher than that of other packaging groups, because straw basket has the function of absorbing water, thereby increasing fruit water loss. The weight loss rate of PE bags with tight bag mouth, vacuum packaging and film punching is lower than that of tray + EVA packaging group, because PE bags have low water permeability and inhibit water evaporation, while EVA (ethylene vinyl acetate film) has high water permeability [9]

Table 2 storage results of Chinese olive fruit treated with different packing materials and packing patterns [stored at (8 ± 1) ℃ for 75 days]

processed fruit rate/% weight loss rate/%

film perforated PE bag tied tightly PE evacuation tray +eva straw basket +pe 96.40a a 95.40ab ab 95.10abc ABC 90.70bc ABC 76.90d 0.61 a 0.80 a 0.80 a 3.00 B 14.10 C C

note: those with large and small letters attached to the same column indicate that the difference reaches a very significant level of 1% and a significant level of 5% respectively

2.3 effect of packaging on the weight loss rate of olive fruit

after harvest, the unpacked olive fruit is very easy to lose water and shrink, affecting the edible quality and commodity value of the fruit. Packaging and storage with 0.04 mm thick polyethylene film bags can effectively avoid the rapid water loss and wilting of fruits. The weight loss rate of fruits between packaging and unpacking is extremely significant at 2 ℃, 6 ℃, 10 ℃ and normal temperature (P <0.01) (Table 3)

Table 3 Effect of packaging on weight loss rate (%) of olive fruit

table 3 Effect of packaging O1 The temperature control meter, timer and other functional parts on the control panel should not be used in the following places: N rate of weight loss (%) Of Chinese olive fruit

storage temperature

packaging method 2 ℃ storage 15d storage 30d storage 6 ℃ storage 15d storage 30d storage 10 ℃ storage 15d storage 30d normal temperature storage 15d storage 30d

unpacked packaging 26.33a0.17b 45.13a1.00b 27.67a0.17b 47.73a1.13b 30.00a0.33b 50.93a 1.20b 43.15a 0.40b 59.80a 1.39b

note: the same column of numbers are followed by capital letters respectively.It means that the difference reaches a very significant level of 1%

3 conclusion

it is better to use PE bags for different packaging materials of olive fruit, and the effect of storage and fresh-keeping with film perforated packaging is the best. When it is kept fresh at (8 ± 1) ℃ for 75 days, the good fruit rate is 96.40%, and the weight loss rate is 0.64%. The fruit is still fresh green and full, with the original flavor, color and quality of fresh fruit; The thickness of PE bag, as the storage and fresh-keeping packaging material of olive fruit, should be 0.06 mm; Packaging with PE bags can effectively inhibit the shrinkage of olive fruits due to water loss, thus prolonging the fresh-keeping period of olive fruits

(author/Chen lianlin, he tongweng bonus, Liu mushui)

source of information: packaging and food machinery