Effect Of Controlled Atmosphere Storage On The Metamorphism Of Microorganisms Inoculated Freshly Squeezed Juice

The sales and sales increase rate of freshly squeezed juice were rapidly growing, but its shelf life was short and it was easy to go bad. Therefor extendding the shelf life of fresh juice had became the key factor to promote the development of fresh fruit juice industry. Controlled atmosphere storage has been acknowledged as the best storage technology. Freshly squeezed juice composition is complicated, the process of metamorphism mainly caused by the fermentation of Saccharomyces cerevisiae, Aspergillus niger and other microorganisms. Controlled atmosphere storage affects juice metamorphic process by influencing Saccharomyces cerevisiae and Aspergillus niger. This article studied Saccharomyces cerevisiae, Aspergillus niger, and the change of overall composition in the freshly squeezed juice to discusses the effect of controlled atmosphere storage on fruit juice metamorphic process.In this paper the different freshly squeezed juice was inoculated in a certain amount of Saccharomyces cerevisiae or Aspergillus niger, and then stored under different proportions of CO2 gas(20%, 40%, 60%, 80%). During the storage, the main composition conversion quantity of saccharides, acid, alcohol, aldehyde and the environment gas were measured. The effects of controlled atmosphere storage on the metamorphism of microorganisms inoculated freshly squeezed juice were investigated. The main results are as follows:(1) The affect of low concentration CO2 on the Saccharomyces cerevisiae and Aspergillus niger in the the freshly squeezed orange juice were weak, but when the CO2 concentration was high, it could lead inhibition of the consumption of saccharides.In 60% CO2 group, the Saccharomyces cerevisiae in the juice was influenced and its main metabolite was alcohol. When the initial concentration of CO2 was 40%, the main metabolite of Saccharomyces cerevisiae was acid. And in this case, this controlled atmosphere could restrain the bleeding of Saccharomyces cerevisiae, reduce the number of Saccharomyces cerevisiae and the consumption of saccharides. Besides under the condition of high concentration CO2,the alcohol was the main metabolites(alcohol quantity was more than acid). Besides the conversion rate of saccharides increasesd with the increasing of CO2 concentration, 60% CO2 concentration reached the peak and then began to decline.(2) Freshly squeezed Cherry tomatoes juice was inoculated in Saccharomyces cerevisiae or Aspergillus niger, and then stored under different proportions of CO2 gas. During the storage, high CO2 concentration could Inhibit of the consumption of saccharides. inhibit generating acid, and at the same time promote the generation of glycolys.Only when the CO2 concentration was high enough, it could inhibit the generation of volatile acid.But the affect of Aspergillus niger on the juice was opposite trend, high concentration of CO2 could lead to the degradation of saccharides to produce acids substances, and inhibite alcohols. At the same time, the high concentration of CO2 is conducive to the generation of volatile acid in juice.(3) Freshly squeezed watermelon juice was inoculated in Saccharomyces cerevisiae or Aspergillus niger, and then stored under different proportions of CO2 gas. During the storage, high CO2 concentration could inhibit of the consumption of saccharides, at the same time it inhibited the generation of acid and promoted the fruit juice saccharidest to degradate to produce alcohol. Besides, the pathway of degradating saccharides to generate volatile acid was suppressed.Under the affecting of Saccharomyces cerevisiae, high concentrations of CO2 could reduce the conversion rate of saccharides to alcohol and acid, and it was advantageous to storage watermelon juice. The influence of Aspergillus niger on the juice was similar to Saccharomyces cerevisiae, the balance of saccharides conversion moved to alcohol conversion direction, leading to generate a large mount of alcohol.But the different was that along with the increaing of the initial CO2 concentration, the saccharides conversion rate increased, reached the peaked at 60% and then decreased.(4) The cherry tomatoes juice were included in Aspergillus niger,as the CO2 concentration increasing,the consumption rate of the saccharides decreasesd gradually. High concentration of CO2 could lead the degradation of saccharides to produce acids substances, and inhibite alcohols. At the same time, the high concentration of CO2 is conducive to the generation of volatile acid in juice.(5)When the freshly squeezed juice was inoculated in Saccharomyces cerevisiae and stored under different proportions of CO2 gas, the conversion rate of saccharides to acid could reduce in the peracid juice by improving the CO2 concentration.At the same time,the balance of saccharides conversion moved to alcohol conversion direction. When the juice had little acid,the variation trend was opposite. So saccharidest metabolic process of different acidic juice could be controlled by controlled atmosphere.(6) When the high glucose freshly squeezed juice was inoculated in Aspergillus niger and stored under different proportions of CO2 gas,along with the increasing of the initial CO2 concentration, the saccharides conversion rate increased,and it was bad to store the juice.So,when the Aspergillus niger was the main microbial flora in the high glucose freshly squeezed juice, the low CO2 concentration would be good for storage.(7) When the Saccharomyces cerevisiae was the main microbial flora in the freshly squeezed juice, the volatile acid content could be reduced by improving initial CO2 concentration, especially for acidic fruit juices.And the trend was opposite when the Aspergillus niger was the main microbial flora,especially for acidic fruit juices,too.Therefor to control the volatile acid content by controlled atmosphere should take different varieties of fruit and main influencing microbial flora into account.