Effect Of Ca²⁺ On Taste Quality Of Green Tea Infusions And Its Stability

The assessment of tea beverages is not only depends on the color, the aroma and the taste, but alsothe content of main chemical components and the stability of shelf life. Water is one of the mostimportant raw materials in the tea beverage processing. Usually the solids content of pure tea beverageis0.20%-0.50%, and juice or fruit-flavored tea drinks solids content is below20%, so the proportion ofwater in the tea beverages is generally more than80%. Ca²⁺had some important influence on the flavorof tea quality and biochemical component content, such as tea flavor deterioration, biochemicalcomposition changes, tea cream and tea bubble appeared. On the basis of previous experience, thisstudy selected typical water to analyze and study, and got the key factors that affecting the beveragequality and storage, which were pH value and Ca²⁺concentration. This paper chose typical metallicelements (Ca²⁺) as the research object to discuss the effect of Ca²⁺on taste quality and stability of greentea infusions. The main results are as follows:1. Calcium content and pH value of water samples were the key factors affecting the quality andstability of the tea extracts.There were obvious differences between the8types of typical commercialwater in the pH value, conductivity and the content of the main mineral elements. There was a certaincorrelation between the tea extracts and the water samples in the content of the main mineral elements.Different type of water significantly influenced the contents of polyphenols in tea infusions, while therewere not have statistically significant differences（p＜0.05） in the content of caffeine and amino acid.The aging effect had some influences on the main chemical compositions, and made the liquor color andsensory quality deterioration.2. Ca²⁺can affect the taste quality of tea infusions made by different cultivars and pluckingstandard. With the increase of Ca²⁺concentration, bitterness and astringency intensity change. Ca²⁺canincrease the bitterness of the tea that made by Longjing43cultivars and the one leaf plucking standard.Ca²⁺can increase the taste of astringency.3. Ca²⁺can affect the taste of tea taste composition, reduce the strength performance of eachcomponent, and make the taste dull. Ca²⁺can increase the astringency of EGCG components. Papercarried out the pairwise complex test between two components and tasted the two blended componentsto probe the effect interaction. Ca²⁺can increase the intensity of astringency taste for the treatmentcontains EGCG, which can conjecture that EGCG was an important reason that made tea infusionsastringency increased by Ca²⁺.4. Ca²⁺is an important factor for quality instability of tea beverage, which would change the tastequality and aggravated the deterioration of tea beverages. During storage, the pH value decreases alongwith the extension of storage time, and Ca²⁺can strengthen the change. In pH6.5, Ca²⁺can affect thebeverages color, aroma and taste. In the process of storage, caffeine content dropped, the free aminocontent increased at first and then decreased, the flavonoid content increased at first and then flat, thecatechins decreased significantly. Ca²⁺has differently influences on the main chemical compositions andcatechins of tea beverage under the different pH value.