Keywords:Plant extract,Anticorrosion
In recent years, the use of natural plant extracts instead of chemically synthesized substances as fruit and vegetable preservatives has become a research hotspot. The main means to control postharvest diseases of fruits and vegetables is to refrigerate and preservatives. However, the preservation of fruits and vegetables with chemical preservatives is harmful to both fruits and vegetables and human health. China started late in the research of natural preservatives, but has also achieved good results.
1. The effect of natural plant extract on fruit and vegetable decay
There are many types of natural plants used for the preservation of fruits and vegetables. There are more than 5,000 kinds of Chinese herbal medicine, including some spices and plants rich in flavonoids.
Researcher shown that garlic extract can inhibit the gray mold fungus of tomato, and it has been found that garlic extract can inhibit the spore germination and mycelial growth of gray mold. At a dilution concentration of 10.0 μL / mL, the inhibition rate on spore germination reached 100%.
The higher concentration of garlic, leek water extract and clove, and rhubarb decoction have stronger inhibitory effect on Rhizoctonia solani and Gliocladium anthracis when the concentration is higher, and at a lower concentration, there is no obvious effect or slight growth promotion Effect; various concentrations of forsythia decoction have strong inhibitory effect on anthracnose and have no obvious effect on Rhizoctonia solani.
95% ethanol extracts of 7 Chinese herbal medicines including peppermint, Cnidium, gentian, knotweed, Andrographis paniculata, Paeonia lactiflora, and betel nut were used to conduct an antibacterial activity test on anthracnose apple, Venturia nashicola, and tomato fusarium. The results showed that the antifungal effect of Cnidium and Giant Knotweed Rhizome on tomato Fusarium and apple anthracnose was better.
2. Inhibitory effects of different extraction methods on rot-causing bacteria in fruits and vegetables
Different methods of extracting active ingredients from natural plants have different antibacterial effects.
Using cloves as raw materials, the inhibitory effects of clove essential oil obtained from supercritical CO2 extraction, steam distillation, and water heating distillation on post-harvest pathogens of fruits and vegetables were studied. The results showed that clove essential oil had a good antibacterial effect on grapes, jujube, peach, garlic tincture and so on. Among the three different extraction methods, the steam-distilled essential oil had the best antibacterial effect, followed by supercritical CO2 extraction, and the effect of direct heating water distillation was poor.
Using Botrytis cinerea as a test bacterium, the effects of the frequency, time and dosage of the effective components of traditional Chinese medicine on the antibacterial effect of ultrasonic extraction were studied. Experiments show that this method has a high extraction rate, strong reliability, simple operation and short extraction time.
3.Research on the Fresh-keeping Effect of Plant Extracts on Fruits and Vegetables
The garlic, ginger, and orange peel are mashed into a paste, the supernatant is centrifuged, and the extract is compounded into a preservative for grapes, green peppers, and tomatoes. The appearance, weight loss rate, pH value, soluble solids, and vitamin C content of fruits and vegetables treated with freshness keep little change, which can prolong the storage period without affecting the original flavor.
Use rhubarb, honeysuckle, and galangal to keep fresh cucumbers, soak the cucumbers in the Chinese herbal medicine filtrate, and take them out to dry. The results showed that the sensory quality, vitamin C retention rate, and water retention were better than those of cucumber without preservatives.
The plant extract has a good bactericidal effect, is not harmful to the human body and the environment increases the safety of eating fruits and vegetables, and has a good effect in keeping fruits and vegetables fresh. In the long run, the research direction of fruit and vegetable preservatives should develop in a natural, safe and effective direction. Natural plant extracts have broad prospects for the storage and preservation of fruits and vegetables instead of chemical synthetic preservatives.
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