Researcher Feng Yuqin, Gansu Academy of Agricultural Sciences, et al.: Screening and verification of the area of spontaneous modified atmosphere silicon window of broccoli silicon window based on temperature conditions

Broccoli not only has a comprehensive nutritional composition, but also has a higher content of active ingredients such as glucosinolates and its derivative sulforaphane with health care effects than other cruciferous vegetables, and is known as
the "vegetable crown".
However, after harvest, broccoli has strong physiological metabolism, which is very easy to yellow, lose water and wilt at room temperature, and rapidly lose nutrients, resulting in a decrease
in its commodity value.
Although traditional preservatives can prolong the storage period of broccoli, there are secondary residues
.
Modified atmosphere preservation technology is green and safe, and is one of
the modern fruit and vegetable storage and preservation methods widely used at home and abroad.

Spontaneous modified atmosphere preservation is to seal fruits and vegetables in a container made of plastic film with specific breathable properties, using the respiration of fruits and vegetables themselves and the breathability of plastic film, under certain temperature conditions, self-adjust the O2 and CO2 content in the sealing environment to make it meet the storage requirements
.
Silicon window atmosphere control is a kind of spontaneous atmosphere control, which is embedded with a certain area of silicone rubber film on the packaging container, and uses the permeability of the silicone rubber film to select different gases to adjust the proportion
of gas in the packaging environment 。 Wei Lijuan and Feng Yuqin* of the Institute of Storage and Processing of Agricultural Products, Gansu Academy of Agricultural Sciences, and the Fruit and Vegetable Storage and Processing Technology Innovation Center of Gansu Province used cold-resistant excellent broccoli as the material, and proposed to process broccoli by setting different storage temperatures and silicon window area packaging, to explore the effects of storage temperature and silicon window area on the effect of broccoli silicon window controlled atmosphere preservation, and to determine the optimal parameter combination of spontaneous modified atmosphere of broccoli silicon window, in order to effectively inhibit the postharvest yellowing of broccoli and delay the quality deterioration of broccoli during storage.
It provides a theoretical basis
for the spontaneous modified atmosphere preservation technology of broccoli silicon windows.

1.
The effect of packaging bags with different storage temperatures combined with theoretical silicon window area value and ordinary PE packaging bags on the preservation effect of broccoli

Changes in respiration rate and relative conductivity

As shown in Figure 1A, broccoli belongs to respiratory transition vegetables, its respiration rate during storage generally shows a trend of first increasing and then decreasing, there are respiratory peaks (in terms of CO2, the same below), respiratory peaks occur in each group at 5 days, the respiratory peaks of the silicon window bag packaging treatment group are lower than those in the silicone-free window control treatment group, and the respiratory peak of the 2 °C silicon window bag packaging treatment group is the lowest, which is 26.
0%, 68.
4%, 36.
9% lower than the 4 °C silicon window, 4 °C silicon-free window, 2 °C silicon-free window, 0 °C silicon-free window, and 0 °C silicon-free window, respectively.
5.
1%、53.
8%
。 The respiration rate of each treatment group decreased to varying degrees after the peak of respiration, among which the respiration rate of the 2 °C silicon window bag packaging treatment group was the lowest at 10 and 20 days and at the end of storage, and significantly lower than that of other groups (P<0.
05) at 10 and 20 days, and the inhibition effect of 0 °C silicon window bag packaging treatment on respiration rate was inferior to that of 2 °C silicon window bag packaging treatment.
The respiration rate of the 0 °C silicone-free window group during storage was also greater than that of the 2 °C silicone-free window group as a whole, which may be caused by<b11> frostbite of broccoli due to systematic error dropping below the freezing temperature of broccoli.
The 4 °C silicone-free window packaging treatment group had the highest respiration rate throughout the
storage period.

It can be seen from Figure 1B that the relative conductivity of each treatment group gradually increased with the extension of storage time, among which the 4 °C silicone-window-free control group increased rapidly, and after 10 days, it was significantly higher than that of other treatment groups (P<0.
05), and the relative conductivity of the silicon window bag packaging treatment group was lower than that of the silicon-free window control treatment group<b10> in the late storage period 。 The relative conductivity of the 2 °C silicon window bag packaging treatment group was lowest after 5 days until the end of the storage period, and the 4 °C silicon window, 4 °C silicon-free window, 2 °C silicon-free window, 0 °C silicon window, and 0 °C silicon-free window were 11.
2%, 30.
1%, 12.
1%, 1.
2%, and 15.
9%,
respectively.
The relative conductivity of the 0 °C silicon window bag packaging treatment group increased faster than that of the 2 °C silicon window bag packaging treatment, and the 2 °C and 0 °C silicon-free window control groups had a similar change trend, because the low ambient temperature of the 0 °C treatment group caused damage to the broccoli cell membrane.

Changes in the volume fraction of oxygen and carbon dioxide in the bag

Silicon window can effectively adjust the gas composition in the packaging bag, from Figure 2, it can be seen that the change trend of O2 and CO2 volume fraction in each silicon window packaging bag is more stable than that in each silicon-free window packaging bag, silicone-free window packaging bag due to poor air permeability, the O2 volume fraction in the bag is sharply reduced, and the CO2 volume fraction accumulates too much, which is not conducive to broccoli storage
.
The O2 volume fraction of the 2 °C silicon window bag packaging treatment group within 5~25 d remained between 2.
3%~4.
1%, the volume fraction of CO2 remained between 8.
7%~11.
0%, and the gas ratio in the bag reached dynamic equilibrium, which was closest to the best storage gas environment
of broccoli.

Changes in chlorophyll, VC, soluble protein, and glucosinolates