Study On The Change In Quality Of Bamboo Shoots In The Fermentation Process Of Lactic Acid Bacteria Preparation

Bamboo shoots(Dendrocalamus latiflorus) are rich in nutrients that human body needs, which taste crisp and delicious.But fresh bamboo shoots has a certain bitter taste. The traditional handling method is to carry out the natural pickle fermentation process on bamboo shoots(Dendrocalamus latiflorus).On the one hand,this method improve the taste and flavor of bamboo shoots.On the other hand,this process make bamboo shoots be preserved longer. The natural pickle fermentation process’s time tends to be so long that the quality is difficult to control and more security risks appear.This study was designed to select suitable lactic acid bacteria strains from natural fermented sour bamboo shoots, and to prepare a lactic acid bacteria preparation, and investigate the effect of the addition of the lactic acid bacteria preparation and salt on the quality of the bamboo shoots. The main contents and conclusions are as follows:First,23 strains of lactic acid bacteria were selected from the self-made natural fermented acid bamboo shoot, and the improved MRS culture medium was used for the screening. By comparing the growth rate, acid production rate, flavor and nitrite degrading ability,4 strains of lactic acid bacteria, which are suitable for pure breed fermentation, were obtained.They are called Rue.2, Lug.l, Lug.2 and Rue.l. Comparison of the fermenting ability among the 4 strains of lactic acid bacteria,the result showed that Rue.2 and Rue.1 have better adaptability of acid and salt, acid production faster and stronger degradation ability of nitrite. The most suitable growth pH values of Rue.2 and Rue.1 were pH6-pH8.Therefore, Rue.2 and Rue.l ware selected as the strains of lactic acid bacteria fermentation agents.Secondly, compared with the natural fermentation method and pure lactic acid bacteria fermentation, the addition of salt and the lactic acid bacteria preparation at the same time brought lower content of nitrite, fast acid production and better taste. This method is more suitable for the fermentation of bamboo shoots(Dendrocalamns latiflorus).The results of experimental showed that the nitrite content of second days was 4.11 mg/kg when the dosage of lactic acid bacteria preparation was 1%-2%; When the addition of lactic acid bacteria preparation up to 2%-4%, the nitrite content showed a slow decline after the first stable period, and the nitrite content was not more than 4.0 mg/kg (upper limit of the national standard).Meanwhile, a better sensory quality had been achieved. After adding salt, the product has a good taste.when the salt quantity between 2-4%, we can achieve the best taste (the sensory score can reach the highest score of 8.71 points). The comparison of the fermentation temperature showed that the product with the lowest nitrite content when the temperature was 25 ℃, and the texture was better. Adding a small amount of sugar is beneficial to improve the taste, but it has no significant effect on the nitrite content.Finally, based on experiment of single factor, the technological conditions of the pickled process were optimized by response surface method (RSM). The best technological conditions were:the amount of lactic acid bacteria preparation was 3.67%, the amount of salt added was 4.87%, the fermentation temperature was 24.2%.In this way,we can obtain pickled bamboo shoots with nitrite content was 0.61 mg/kg.