The Research On Antimicrobial Properties Of The Complex Fresh-keeping Agent (OAA-7) And Its Application On Fruits

The freshness-keeping agent of fruits (OAA-7), which is proportioned by naturalorganic acids (eg. ascorbic acid, citric acid and lactic acid) and some adjuvants (eg.sodium chloride, calcium chloride and glycerol), is a kind of natural preservatives.With the advantage of excellent stability in performance and convenience in using,this product can dissolve in water with arbitrary proportion. This research studied theantibacterial characterization, antibacterial activity comparing with Nisin and theapplication on some fruits (eg. strawberry, tomato and banana) of this combination ofcertain preservatives (OAA-7).The antibacterial characterization of OAA-7 research showed that OAA-7 couldinhibit the growth of gram-negative bacilli (G~+), gram positive bacilli (G~-) and mildew.Such factors as temperatures and pH values on effect performed in dissimilar degree.The activity test indicated that, with the temperature increasing, the activity of OAA-7gradually decreasesed at temperature above 45℃. The effectiveness of acidity onantimicrobial activity decreased according to the order of weak acid (pH4.5), strongacidic and alkaline condition. In the inhibition experiment of Bacillusstearothermophilus, Staphylococcus aureus, Bacillus subtilis and Listeria, we foundthat the bacteriostatic efficacy of OAA-7 was better than that of Nisin.In this research, OAA-7 has been applied in strawberry, tomato, juicy peach andbanana fruits, and the results indicated that after being dealed with OAA-7preservative solutions under appropriate concentration, the weight losses ofstrawberry, juicy peach and banana fruits decreased during storage. Moreover, thistreatment was beneficial to inhibit fruits decay, keep pulp firmness, and preventvitamin C from being oxidized effectively and it was beneficial to the loss of organicacid. The effect of juicy peach fruit storage treated by OAA-7 followed by heattreatment (with the temperatures of 45±1℃, and humidities ranging from 90% to95%) and cold storage (1.0±0.5℃) was best of all, which was followed by juicypeach, strawberry and banana fruits stored under normal temperature. But storageunder normal temperature had little effects on tomato.