Research On Bionic Tactile And The Conventional Method Of Testing The Meat Freshness

Food safety is the hottest public issue today. Stale meat can cause food poisoning, or even death. Food safety has a close relationship to our health and safety.Nowadays, meat-testing is mainly implemented in conventional ways. Routine testing includes sensory, Physical and Chemical Indicators and microbiological testing. Sensory testing is that the trained people observe the surface, color, elasticity and smell of the meat to decide the freshness of the meat. The advantage of this method is that it can be operated conveniently and easily; moreover it does not require any equipment. The result of sensory testing is close to the criteria of the consumer toward to the meat. Its disadvantage is that the result of the testing can be affected by the objective of the operator, and it is hard to be quantified, unprofessional people cannot perform the test exactly. Physical and Chemical Indicators includes pH value and Volatile basic nitrogen, etc. Until now, only Volatile basic nitrogen is listed as the national standard. It can reflect the change of the freshness of the meat regularly. Moreover, when we use this method to test the fresh meat, ordinary meat and stale meat, respectively, the result is the same as the result of the observation. But this method is hard to be performed on site because of the complex equipment, inconvenience and large data errors.Routine testing method is time-consuming and cannot be satisfied by modern lifestyle. Electronic nose, electronic tongue and bionic tactile have the characteristics of fastness, real time and non-destructiveness, which are required by modern testing. This is the direction of the development in food testing area. In this study, the author used the routine testing method to test the corruption process under different storage conditions, which reveals the relationship between the index in each regular testing method and the freshness of chicken, pork and beef, and the relationship between Volatile basic nitrogen and other regular testing indicators of the chicken, pork and beef. This provides the theoretical basis and reference data to the development of electronic nose, electronic tongue, and bionic tactile.Bionic tactile is originally from the sensory testing. Sensory evaluation of the food quality is the common assessment methods in food testing. It is known that the elasticity of the meat can reflect the freshness of the meat. Over the years, the testing of elasticity of meat entirely relies on sensory testing. This is the basic testing method for the freshness of meat. Sensory evaluation is only the method for testing the meat qualitatively, it cannot test quantitatively. So it is not suitable for large-scale industrial automation testing. Bionic tactile has the advantage of sensory evaluation, and make up the lack of sensory evaluation at the same time. Bionic tactile can test the elasticity of the meat quantitatively. Although bionic tactile testing is still in theoretical stage, it has already shown the advantages of fast testing, no material consumption, no pollution, and no damage of the meat.The experiments in this dissertation are performed using WDW-20J electronic universal testing machine. We use the pressure head of this testing machine as the Bionic tactile to test the Pressure Characteristics Curve (PCC) of the meat. There are two factors can affect the PCC, one is the testing condition, the other one is the original characteristic of the meat. Different testing conditions lead to different parameters of the PCC, but the shape of the curve changes little. The instinctive characteristic of the meat is the determinant of the shape of PCC. Different meat, such as chicken and beef, their PCC is different, even the same kind of meat, because of the different quality of meat, age of animal, feeding condition of animal, testing position of meat, the PCC is different too.To ensure the comparability and accuracy of the test, the size and shape of pressure head, testing speed, maximum lift displacement, types of meat, position of meat for testing, sample size and testing point location should all be determined.This paper has proved that the best experimental parameter for test PCC is:bionic tactile pressure head usingΦ10mm circular flat indenter, the movement distance of upward tray is 4.000mm, the speed of the tray move upward is 120mm/min, and return speed is 120mm/min. The muscles from same position of the same animal of same species are selected as the testing samples. The samples are cut according to the meat texture before experiment, the testing point is determined by the texture of meat (corresponding point physically).According to the above requirements, the fresh chicken, pork and beef which are going to be tested are put in a particular storage temperature. Bionic tactile use the best experimental parameters to measure the PCC. After several days' measurement, through analyzing the relationship between parameters in PCC and Volatile basic nitrogen, we get the relationship between the shape of PCC and Volatile basic nitrogen. The results show that:the shape and parameters of PCC can be reflected the freshness of the meat from different angles. But these parameters are interrelated, all these factors must be taken into account when we determine the freshness of the meat. The results of the experiment show that the PCC are all concave. When the test conditions and test samples is determined, the parameters in the characteristic curve of chicken, pork and beef change regularly with the change of volatile basic nitrogen, so the PCC can reflect the freshness of the meat.The bionic tactile method can test meat within a few seconds in a non-destructive way. This is a promising method which is fast, economical, simple for testing the freshness of meat. Rapid-testing using bionic technology is the trend of development for testing the freshness of meat in the world.