Effect of storability on compounds extracted from Scutellaria baicalensis and other traditional Chinese herbs in kiwifruit

Abstract:【Objective】Kiwifruit is tender and juicy, fresh and delicious, as well as sweet and sour. At the same time, it is loved by people because of its unique nutritional, high health care, certain medicinal and high economic values. However, it is easy to be infected by soft rot pathogens in the process of stor-age and transportation. At the same time, kiwifruit is a kind of respiratory climacteric fruit. In addition,kiwifruit picking season is very hot, which will easily lead to fruit softening and deterioration, seriously affecting the quality and shelf life, so that the storage capacity is very important for the development of the industry. Plant-sourced preservative has characteristics of no pollution, no residue and good preser-vative effect. The treatment of kiwifruit with plant extract can provide reference for improving develop-ment of its scientific and reasonable storage technology in the future, so as to provide theoretical basis for the green postharvest preservation technology.【Methods】The extract of Chinese medicine (Scutel- laria baicalensis, clove, cinnamon, Gleditsia, patchouli, Acorus calamus and Camellia seed meal at the ratio of 1.375∶1.125∶0.450∶0.500∶1.350∶1.250∶2.800) was used as the agent, and the kiwifruit was used as the sample fruit. The treatments were divided into four groups: A-good fruit+medicine group (treated with 0.8 mg·mL-1 Chinese medicine mixed extract), B-good fruit group, C-sick fruit+ medicine group, D-sick fruit group (inoculated with mixed spores of Diaporthe+Botryosphaeria dothidea/1-5×105CFU·mL-1), they were stored in a cold storage at (4 ±1) ℃, and the relevant indexes were measured ev-ery 10 days. Indicators include good fruit rate, weight loss rate, core color, hardness, firmness, acid, vita-min C content, sugar content, respiratory intensity, starch content, pectin content, protein content, amino acid content, catalase activity, peroxidase activity, amylase activity, pectinase activity, peroxidase activi-ty, cellulase activity, ethylene content, and each index was determined for three or more times. At the same time, transcriptome sequencing was used to analyze the fruits stored for 28 days, and principal component analysis of physiological indexes was carried out during fruit storage.【Results】After the ex-tract treatment, it can delay the fruit softening, reduce the weight loss rate and improve the fruit quality rate. For example, on the 30th day of storage, the fruit hardness is 9.70, 8.73, 8.20 and 4.60 kg·cm-2, re-spectively. At the 80th day of storage, the weight loss rate of D group was 11.93%, which was 70.21% higher than that of A group, and at the 80th day of storage, the good fruit rate of the four groups were 86%, 65%, 70% and 6%, respectively. It can delay the decrease of vitamin C and titratable acid contents and delay the increase of reducing sugar, soluble solids, soluble pectin, soluble starch, soluble protein and amino acid contents in the early stage of storage. For example, on the 10th day of storage, the vita-min C contents of the four groups were 233.71, 204, 175.19 and 130.62 mg · 100 g -1, respectively. The contents of soluble solids were 7.76%, 10.76%, 11.73% and 14.66% respectively, the contents of solu-ble protein in D fungus and C fungus+drug group showed the peak value on the 20th day, 16.02% and 15.42%, respectively; the peak values of CK and drug group appeared on the 30th day, 16.14% and 15.56%, respectively. It can increase the activity of SOD, CAT and POD, inhibit or reduce the activity of amylase, pectinase and cellulase. For example, on the 30th day of storage, the SOD activities of the four groups were 5.14, 4.24, 4.06 and 1.67 U·g^-1, respectively. On the 10th day of fruit storage, the CAT enzyme showed the maximum activity, and at this time, the activity of CAT enzyme in the A treatment group reached 0.822 mg · g-1 · min-1, which was 23.47% higher than that in the fungus treatment group. The maximum activity of amylase in fungus treatment group D was 1.690 mg·g-1·min-1 at 20th day. The peak value of amylase in medicine treatment group A and CK group B was at 30th day, but it was far lower than that in fungus treatment group at 20th day. At 20th-30th days pectinase activity was higher in fungus group D than that in other groups (p < 0.01). At 10th day of fruit storage, cellulase activity was 59.57, 71.05, 81.60 and 91.48 U · g-1, respectively. It can delay the occurrence time of respiration and ethylene maximum intensity, and reduce its respiration and ethylene release. For example, on the 10th day of storage, the respiratory intensity of the treatment group A was significantly lower than that of the other treatment groups (p < 0.01), and on the 10th day of storage, the respiratory intensity of the treatment group A was 29.14% lower than that of the treatment group D. The ethylene release of group D reached a peak value of 2 440.36 1 nmol · kg^-1 · h^-1 at 20th day storage, while that of the other three groups reached a peak value at 30th day storage, and at the moment, the lowest ethylene release of group A was only 1 939.611 nmol · kg^-1 · h^-1. By transcriptome analysis, it was found that the transcrip-tional level of metabolic pathway of fruit in each group was basically consistent with the level of physical and chemical indexes (antioxidant enzyme activity, ethylene metabolism, respiratory- energy metab-olism, macromolecular catabolic enzyme- polysaccharide metabolism). For example, the levels of achn217211 amylase in four groups were 146.7, 166.3, 179.1 and 225.4, and the enzyme activities were0.79, 0.91, 1.15 and 1.69 mg·g^-1·min^-1, respectively. The levels of PEPCK were 76.56, 109.2, 154.4 and 164.1 in the four groups, and the respiratory intensity of fruit was 47.56, 54.75, 61.23 and 67.12mg·kg^-1·h^-1, respectively. Principal component analysis was used to analyze the storability of kiwifruit.The changepattern of principal component analysis results was consistent with the change of the test re-sults. Two principal components were obtained in each treatment, and the contribution rate of principal component 1 was about 55%. It mainly reflected some physiological and biochemical indexes (hard-ness, acidity, vitamin C, starch, pectin, POD enzyme, etc.) in the fruit, which generally showed the trend of“high to low”. The contribution rate of principal component 2 was about 40%, which mainly reflected some physiological and biochemical indexes (soluble solids, sugar, amino acids, respiration, protein, amino acids, amylase, pectinase, cellulase, etc.), which showed the trend of“low high low”in the fruit.【Conclusion】The storability of fruit in D group was the worst, B group and C group were general,and A group was the best. Traditional Chinese medicine extract can effectively improve the fruit shelf life and prolong the storage quality of fruit. It is a good plant-sourced preservative and can be widely used in the storage and preservation of kiwifruit.