369 reviews 26 O’Hagan. D. T. et al. (1991) Inwunulogy 73, 239-242 34 Marx, P. A. ef al. (1993) Sriew 260. 1323-1327 27 Nakaoka. R., Tabata, Y. and Ikada. Y. (1996) vaccine 14, 1671-1676 35 Whitturn-Hudson, J. A.. An. L.. Saltzman, W. M., Prendergast, K. A. 28 Cleland, J. L. et al. (1996)J. PIwwt. Sti. 85, 135(!-1357 and MacDonald, A. B. (1996) Xt. Med. 2, 1116-I 121 29 Eldndge. J. H. rt al. (1989) Curr. Top. Microbial. Immwol. 146, 59-66 36 Lemon, S. M. andThomas,D. L. (1997) iVavEngl.J Afed. 336, 196-204 30 Eldndge, J. H. et al. (199O)l. Control. ReI. 11, 205-214 37 Ma, J. K-C. et al. (1995) Scierxe 268, 716-719 31 O’Hagan. D. T. et al. (1995) Ado. Exp. bfed. Biof. 371B, 1463-1467 38 Haq, T. A., Mason, H. S., Clements, J. D. and Amtzen, C. J. (1995) 32 Jain, S. L., Barone, K. S. and Michael, J. G. (1996) Cell. Iwnwzol. 167, S&we 268, 714716 17&175 33 Jain, S. L., Barone, K. S., Flanagan, M. P. and Mxhael, J. G. (1996) C’uuine 14, 1291-1297 39 M&at, A. S. (1995) Srietlce 268, 658459 40 Thanavala, Y., Yang, Y-F., Lyons, P., Mason, H. S. and Amtzen, C. (1995) Proc. Natl. Acad. Sri. U. S. A. 92. 3358-3361 Developments and applications of biosensors in food analysis John H. T. Luong, Pierre Bouvretteand KeithB. Male The food industry needs suitable analytical methods for process and quality control; that is, methods that are rapid, reliable, specific and cost-effective in their provision of information about physical and chemical characteristics of food. Apart from a few important analytes, such as sugars, alcohols, amino acids, flavours and sweeteners, food applications mainly focus on the determination of contaminants. However, very few biosensors play a prominent role in food processing or quality control. Considerable effort must be made to develop biosensors that are inexpensive, reliable, and robust enough to operate under realistic conditions. Reliable and cost-effective analytical methods are increasingly needed in the food industry for the deter- mination ofspecific chemical compounds in foods and food products. The need arises from increased regulat- ory action and heightened consumer concern about food composition and safety. It has been estimated that the food industry spends, on average, 1.5 to 2% of the value of its total sales on quality control and appraisal. For example, several million penicillin assays for mas- titis are performed on cattle milk in US dairy farms every year. Contamination of foods by toxins (e.g. domoic acid in mussels, tetrodotoxin in fish), viruses (e.g. hepatitis A) or microorganisms (e.g. Escherichia coli, Salmonella, Listeria) is a serious concern. The recent bovine spongiform encephalopathy (BSE) out- break in the UK, as a result of which several million cattle and dairy products were ordered to be destroyed, has not been quickly forgotten. According to the Cen- ter for Disease Control and Prevention (Atlanta, USA), 6.5 million illnesses and 9000 deaths occur every year in the USA because of foodborne bacterial contami- nation’. Food products now require extensive labelling J. H. T. Luong (john.luong@nrc.ca), P. Bouvrette and K. B. Male aye at the Biotechnology Research Imtitute, Nutional Research Council Canada, Montreal, Quebec, Canada H4P 2R2. of all their major and minor constituents - artificial flavours and sweeteners, antimicrobial agents and aller- gens, glucose in sugars and syrups, alcohols in wine, hydrogen peroxide and sulphites as preservatives, antibiotics in milk, cholesterol, glutamate and vita- mins, to name just a few. The contribution of analyti- cal services in the food industry is also becoming increasingly important in the monitoring of raw ma- terial conversion and composition, verification of product contents and evaluation of product freshness (see Table 1 for more applications). Various analytical methods have been developed and applied to food analysis that can provide information concerning the exact physical and chemical characteristics of food, including data about contaminants. However, con- ventional methods such as chromatography are time- consuming, requiring sample pretreatment, expensive equipment (e.g. multidetector systems, chromato- graphic columns) and high-purity chemicals as mobile-phase modifiers. Biosensors, an amalgamation of signal transducers and biocomponents, are expected to play a prominent role in food processing and quality control. Compact- ness, portability and high specificity and sensitivity are among the reasons that biosensors provide consider- able promise and potential for replacing current ‘wet’ Copyright 0 1997, Elsevier Science Ltd. All rights reserved. 0167 - 7799/97/$17.00. PII: SO167-7799(97)010718 TIBTECH SEPTEMBER 1997 (VOL 15)