[Study on the deteriorating course of fresh milk by laser-induced fluorescence spectra]

Along with the development of living standard, people's demand for food quality and food hygiene also rises. People demand food not only with rich nutrition, inexpensive price, but also with safety. So food hygiene test is paid common attention of society. Milk is a nourishing food and is loved by people. Sour milk goods from milk is also in great demand. But nourishing foods are good for growing many microbes. Fresh milk and sour milk are easy contaminated by microbes and go bad. Laser-induced fluorescence (LIF) technology is an important part of modern optics. It is broadly applied in biomedicine, diagnostics, test of food hygiene, environment protecting, owing to its high sensitivity, high speed, automation, untouched testing. In this paper, we attempted to LIF technology to test milk food quality. We used the third harmonics pulsed Nd:YAG laser (355 nm) as the exciting source, and a multi-track spectrometer as the detector and measured the intensities of apply LIF of fresh milk and sour milk during their deteriorating course. Test system and test method are introduced, fluorescence spectra of deteriorating course are also attached. The test result makes clear that there are close connection between deteriorating course and fluorescence spectra.