The Establishment And Application Of The Determination Method Of Raw Juice Content In Juice

Raw juice content is the main quality indicator of fruit juices and is an important basis for determining whether the juice is adulterated or not. Effective standards are used only for orange juice, while for other fruit juices, there are no effective detection methods for the raw juice content.In this study, detection methods of the raw fruit juice content and part ingredients of six self-made and six supermarket juices were determined. The six self-made juices included the Shanxi Guoguang apples, Shaanxi yellow banana apples; Shandong Gala apples, Yancheng Gala apples, Henan Red Fuji Apple and Lianyungang Red Fuji Apple. The study showed that the protein, moisture, ash, soluble solids and the total sugar contents were insignificant (t-test, P>0.05) in the self-made apple juice, while the protein and ash contents in apple juice from the supermarket were significantly lower than the self-made juice (t-test, P<0.05).Results from the atomic absorption spectrometry (AAS), high performance liquid chromatography (HPLC) and colorimetric detection methods indicated that apple juice content had a good quantitative relationship with the characteristic components:amino acid nitrogen, potassium, phosphorus, total flavonoids and L-malic-acid, as the determined parameters. The standard value, weight value distribution plan and the principles of amendments for abnormal data of the three components were also defined. Accordingly, the formula for calculating apple juice content was derived; five-detection-parameters method was developed. The self-made apple juice was studied by five-detection-parameters method, which showed a raw juice content of90%to107%, values close to100%, while the fruit juice from supermarket were significantly lower than the self-made juice; Only one juice from the supermarket had a raw juice content of105%while the remaining five ranged from6%to64%. Studies on the relationship between apple juice buffering capacity and the original fruit juice content and buffering capacity test method was also developed.The two methods can be used for the determination of the raw juice content of apple juice or used to identify the authenticity of the juice. However, it was found that determination was influenced by the buffer material added such as, organic acids and amino acids. As such, the buffering capacity test method is inappropriate in making the determination, since it has some limitations. Thus, five-detection-parameter method is more superior to the buffering capacity test method.The method was used to test the raw juice content in four self-made grape juice and four grape juice from the market. The results showed a raw juice content of98%to102%, values close to100%. This shows that the method can be applied in grape juice.