| Tomatoes were popular with many people because of high edible and medical care value. There are some difficulties in transporting and selling owing to some factors including fruit thin and juicy, susceptible to postharvest damage, shorter shelf-life and poor storage and transport. Therefore, the development and improvement of the keeping quality technology of tomato brought remarkable economic and social benefits. In the paper, two kinds of physical and chemical methods on fresh-keeping were used to study the effect on the quality of the tomato and the physiological and biochemical. Specific results are as follows:(1) Fresh-keeping effect of plastic film and low temperature(4 ℃) on tomatoThe results were shown that the rate of water loss of tomato could be better controlled in the plastic film group and low temperature group compared with control group. Water decreased by 20.4% and 38.5% in the plastic film group and low temperature group compared with the control group, respectively. The color and brightness of tomato were maintained in the treatment group. As far as TA was concerned, when tomato fruits were stored for 21 days, the TA values of room temperature group decreased by 26.8%, those of the plastic film group decreased by 22.1% at room temperature, those of low temperature group decreased by 12.9%. When tomato fruits were stored for 21 days, the contents of VC in the control group were 61mg/100 g, those in low temperature group were up to 85mg/100g; The decline rate of malic acid content was slowed down in each treatment group. When tomato fruits were stored for 21 days, the total sugar contents in the control group were 6.32%, those in the plastic film group were 6.07%, and the total sugar in low temperature group was the lowest, which was 5.31%. The content of TSS and carotene in each treatment group slowly increased. At the same time, the formation rates of total phenolic compounds and total flavonoids were increased to a certain extent. The activities of PG enzyme and cellulase were decreased; the time of reaching the peak value was delayed. The storage period and shelf-life of fruits were obviously prolonged, which could better keep the quality of tomato. Generally speaking, the fresh-keeping effects in low temperature group were better than those in the plastic film group.(2) The preservation effect of 0.5μL/L 1-MCP and 2%(w/v) chitosan on postharvest tomato fruitsThe results were shown that compared with the control group, the water loss rates of tomatoes could be better controlled in 1-MCP group(0.5μL/L) and chitosan(2%) group, among which the water content was decreased in 1-MCP group(0.5μL/L) and chitosan(2%) group by 37.1% and 31.4% compared with the control group, and the chroma and brightness of tomato were kept. As far as TA was concerned, the TA contents in the control group fell by 26.8%, those in 1-MCP group fell 17.6%, and those in the chitosan(2%) group fell by 16.6%. As far as VC was concerned, the VC contents in the control group were 61 mg/100 g, the VC contents in 1-MCP group were 74 mg/100 g, and those in the chitosan(2%) were 72mg/100 g. The decline rate of malic acid content was slowed down in each treatment group. As far as total sugar was concerned, when tomato fruits were stored for 21 days, the total sugar contents in the control group were 6.32%, those in 1-MCP group were 5.86%, and those in chitosan were 5.74%. The content of TSS and carotene in each treatment group slowly increased. At the same time, the formation rates of total phenolic compounds and total flavonoids were increased to a certain extent. The activities of PG enzyme and cellulase were decreased; the time of reaching the peak value was delayed. The storage period and shelf-life of fruits were obviously prolonged, which could better keep the quality of tomato. In terms of water loss rate, tomato color(a/b), total flavonoids, carotene and PG enzyme in 1-MCP group, which were superior to those in chitosan group, while as for other qualities, the fresh-keeping effects in chitosan group were better.(3) The effect of tomato fruits peel and seed removal treatment on quality related indexesThe studies suggest that a large number of proteins, carbohydrates, lipids, minerals, and some important phytochemicals accumulated in tomato peels and seeds. Therefore, it was necessary to study the changes of quality and antioxidant properties of tomato by peel and seed removal treatment. In the experiment, two treatments were carried out on four tomato varieties including peel and seed removal, respectively, and their quality and antioxidant activity were determined, the effect of peel and seed removal on the quality and antioxidant activity of tomato fruits were studied. Experimental results showed that the effect of the two treatments on the water activity were small; Soluble solids were increased in various degree, but increased a little; Seed removal could increase tomato chroma, peeling could reduce tomato shades; After seed removal, only Qilong and Beidou 318 had a small increase in acidity, the rest of the treatment groups were reduced in various degrees; After the two treatments, the content of ascorbic acid in the four tomato varieties decreased. The biggest decline was the peeled Rose Indigo among all the treatment groups, fell by 41%, the peeled group had the greatest impact on ascorbic acid; In terms of total phenolic content, Apart from the seed removal of Rose Indigo increasing by 19.1%. The total phenol contents in the remaining treatment group were decreased; In terms of beta carotene and lycopene, there was no obvious regularity. The detection of free radical activity by DPPH- method, in addition to seed removal of L402 and Rose Indigo being decreased by 16.5% and 7.5%, respectively, the free radical activity in the rest treatment groups was increased, after peeling them, among all the cultivars with the largest increase was Beidou318, which was 29.2%. Using β-carotene linoleic acid model system, the results of antioxidant assay showed the antioxidant activity of Qilong and Rose Indigo decreased after two treatments, while those of L402 and Beidou 318 were enhanced. |
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