Nowadays, reusable materials are used for one of components of construction material, train and automobile or electrical product. However, in case of recycling of paper or plastic, the risk of off-flavor exists and the problem of off-flavor has also actually occurred. In this report, we show the off-flavor caused by recycled paper or recycled plastic.

The off-flavors of beer produced during and after brewing processes were discussed. The off-flavors of beer include these derived from raw materials, water, brewing process, and oxidization after bottling. Even though the trace compounds (ng/L) are included in these off-flavors, the recent development of sensitive devices let us possible to examine these compounds. We discussed the off-flavors which are focused from past to recent years.

Off-flavor is the fault of soy sauce, because flavor of soy sauce is the most important. Typical off-flavor of soy sauce is n -butyric acid which produced by Bacillus strains in Koji manufacture. The prevention of Bacillus strains is cleaning, sterilization and drying of the belt conveyor of soy sauce materials and the equipment of Koji manufacture, because of decrease of n-butyric acid. Second important off-flavor of soy sauce is isobutyric acid and isovaleric acid produced by membrane forming yeast in Moromi manufacture and final production after opening of the cap. The prevention of the membrane forming yeast is high alcohol fermentation and pasteurization before bottling.

The sensory test method and the analytical instrument method are common procedures used to identify sources of unusual odors. The gas chromatograph - mass spectrometer (GC-MS) is widely used as the analytical instrument for these purposes. The selection of optimal sample preparation is critical to obtain good results. In this paper, we explained the principles of the GC-MS, sample preparation methods and new technologies for odor analysis.

It is well known there is a close relationship between taste and flavor of food. In order to identify chemical compounds that characterize taste and flavor, it is necessary to use chemical analyzer together with a sensuous analyzing method. Flavor sensor and taste sensor were developed and are used as the sensuous analyzing method, but it is not possible to identify chemical compounds only by using these sensors. On the other hands, chemical analyzer, such as amino acid analyzer or mass spectrometer, identifies chemical compounds, but their analytical results does not include information about taste and flavor.

We tried to analyze some kinds of commercially available cheese by using amino acid analyzer to specify taste and flavor, and also by using HS/GC/MS combining sniffing system to identify their compounds. We report here the good and useful results as food analysis.