Investigation Of Current Status Of Rongalite Added In Bean Products In Luoyang City

Rongalite scientificly named Sodium Formaldehyde Sulfoxylate, which is an industrial bleach, can decompose into carcinogen such as formaldehyde above 60 degree celsius. And just because of its bleaching action, many lawbreaking traders add it in bean products such as bean curd stick, bean curd, causing great harm to human health. Therefore, there is a very important significance of the strengthening investigation into illegal status of the rongalite added to commercial bean products.Currently, there is no standard method of the detection of rongalite in the bean products in our country. Previous research data shows that sample pre-treatment method is essential to the determination of formaldehyde decomposed by rongalite. While the pre-treatment methods put forward in the literature are complicated and of confused conditions, there is no comparability between different test results, which severely restricts the supervision and inspection of rongalite. The purpose of this study is to determine the best testing conditions of rongalite in bean products, and detect Rongalite content of commercial bean products such as bean curd, bean curd stick, bean curd skin, dried bean curd, etc, in Luoyang, and investigate rongalite status of commercial bean products in Luoyang. Specific contents are as follows:1. The optimization of aqueous thermostat conditionsBy doing the single factor and orthogonal test to the precipitating agent (A), temperature (B) and time (C), we can conclude that the optimum treatment conditions of aqueous thermostat for Rongalite in bean products are as follows: precipitation agent is 12.5 ml sodium hydroxide (4%) and 10 ml of zinc sulfate (10%), time is 45 minutes, the temperature is 80 degree celsius.2. The comparisons of different results after using two different processing methodsFirstly process samples respectively by aqueous thermostat or distillation plant, then detect rongalite content by acetylacetone spectrophotometric, finally calculate recoveries, precisions and detect limits. As a result, the recovery of rongalite handled by aqueous thermostat is from 90.98 percent to 97.17 percent, the relative standard deviation (RSD%) is from2.49 percent to 6.63 percent, the detect limit is 0.109 mg/kg; the recovery of distillation plant method is from 91.40 percent to 98.46 percent, the relative standard deviation (RSD%) is from 2.70 percent to 7.61 percent, the detect limit is 0.083 mg/kg. Two kinds of processing techniques have reached the requirements required by food analysis methodology, where the level range of Sample (rongalite) is from 1 mg/kg to 1000 mg/kg. So we can see that both of the two methods meet the testing requirements.3. The rongalite content testing of commercial bean products in LuoyangRandomly collect bean curd, bean curd stick, bean curd skin, and dried bean curd are in district supermarket and agricultural trade market in Luoyang, detect whether there is rongalite added and perform statistical analysis. The test results are as follows:(1) Relevance ratios of rongalite in bean products such as bean curd, dried bean curdare ,bean curd skin, and bean curd stick are as follows: 42.9 percent, 30.8 percent, 66.7 percent and 75.0 percent. Performing chi-square test to the detection results of bean products with the statistical software SPSS 13.0, X~2 is 27.0870, P﹤0.01, test results are highly significant.(2) Relevance ratios of rongalite in bean products from the supermarket and agricultural trade markets are 30.8 percent and 85.7 percent. X~2 is 9.3632, P﹤0.01, test results are highly significant.(3) Relevance ratios of rongalite in two kinds of packaging such as stereotyped bean and bulk products are respectively 25.0 percent and 54.6 percent. While the chi-square test shows that X~2 is 18.2009, P﹤0.01. So it can be seen that relevance ratios of bulk and stereotyped packaging bean products have highly significant differences.4. The sensory testing of rongalite bean products As can be seen from the comparison of the sensory characteristics between rongalite bean products and normal bean products, there are the following differences by using bean curd and bean curd stick respectively:(1) Rongalite bean curd has uneven white color, small and low porosity, non-natural bean flavor; normal bean curd has even yellow color, larger porosity and a natural bean flavor.(2) Rongalite bean curd stick, which has white and unusually bright color, hard and fragile feeling , will immediately turn white and be easily broken by fingers when immersed in water. The boiling liquid is yellow and turbid; Normal bean curd stick, which has pale yellow color , will slowly turn yellow and not be easily broken by fingers when immersed in water. The boiling liquid is deep yellow and with no turbidity.