INTELLIGENT PACKAGING -PART-V

FRESHNESS INDICATOR

          The idea of freshness indicators is that they monitor the quality of the packed food by reacting in one way or another to changes taking place in the fresh food product as a result of microbiological growth and metabolism (Smolander, 2008). Freshness indicators are designed to respond to chemicals released by food as a result of spoilage; usually an oxidative process is effected by bacteria, yeasts and fungi, which break down food carbohydrates, proteins, and fats to a wide variety of low-molecular-weight molecules, such as CO2 (Mattila et al., 1990), lactic and acetic acids (Kakouri et al., 1997), aldehydes, alcohols (ethanol) (Cameron and Tasila, 1995; Randell et al., 1995), sulfurcontaining species (hydrogen sulphide) (Smolander et al., 1998) and nitrogen containing molecules, such as ammonia (Pacquit, 2007; Horan, 1998) and amines (Wallach and Novikov, 1998; Okuma et al., 2000).

 The pH indicator dyes bromophenol blue, bromocresol blue, and chlorphenol red have been used to create a range of ammonia intelligent inks, comprising dye, resin (poly(vinyl butyral)), plasticizer (tributyl phosphate), and solvent (methanol) (33). In the absence of ammonia or volatile amines, such as putrescine, the films are yellow, but in their presence they are either blue or purple. More recently,Food Quality Sensor International Inc. (FQSI) has used similar pH-sensing technology in their SensorQ^TM, a label that detects the freshness/spoilage level of packed meat and poultry has an orange-colored center in the ‘‘Q’’ when exposed to fresh meat, which turns dark green if the meat is spoiled. The pH indicator dyes used in this sensor appear to be anthocyanins, such as betanin or flavonoid dyes. The SensorQ^TM system is a stick-on label that is used on the inside of packages.

        Freshness indicators provide direct product quality information resulting from microbial growth or chemical changes within a food product. Microbiological quality may be determined through reactions between indicators included within the package and microbial growth metabolites (Smolander, 2003).

        A variety of different types of freshness indicators have been described (Smolander, 2003), the majority of which are based on indicator colour change in response to microbial metabolites produced during spoilage. Freshness indicators based on broad-spectrum colour changes have a number of disadvantages which need to be resolved before widespread commercial uptake is likely.

Commercially available Freshness indicator

§  COX Technologies' "FreshTag" color-indicating tags consist of a small label attached to the outside of the packaging film. It is used to monitor the freshness of seafood products, and consists of a reagent-containing wick contained within a plastic chip. As the seafood ages, spoils, and generates volatile amines in the headspace, these are allowed to contact the reagent, causing the wick in the tag to turn bright pink (Han et al., 2005).

§  Hydrogen sulfide indicators can be used to determine the quality of modified atmosphere packaged poultry products. Freshness indication is based on the color change of myoglobin by hydrogen sulphide (H2S), which is produced in considerable amounts during the ageing of packaged poultry during storage.

REFERENCES

·      AHVENAINEN, R., 2003: Novel Food Packaging Techniques. Cambridge UK: Wood head Publishing, 400 p. ISBN 978-1-85573-675-7.

·      COLES, R., MCDOWELL, D. and KIRWAN, M. J., 2003: Food Packaging Technology. Oxford, UK: Blackwell Publishing, 346 p. ISBN 978- 0849397882.

·      C. Suzuki, J. Chem. Ed. 68, 588–589 (1991).

·      FQSI International, FreshQt smart sensor label web information. Available at http://www.fqsinternational.com/products.htm. Accessed March 2008.

·      International published Patent WO 2006/032025 A1, J. R. Williams, K. E. Myers, M. M. Owens, and M. A. Bonne (to Food Quality Sensor International, Inc.).

·      R. Want, ‘‘Enabling Ubiquitous Sensing with RFID,’’ Computer 37, 84–86 (2004).

·      S. Nambi, S. Nyalamadugu, S. M.Wentworth, and B. A. Chin, ‘‘Radio Frequency Identification Sensors,’’ 7th World Multiconference on Systemics, Cybernetics and Informatics, Dubna, Russia, July 30–August 2, 2003.

·      SUMMERS, L., 1992: Intelligent packaging for quality. So_ Drinks Management International, Vol. 36, p. 32–33. ISSN 0953–4776.

·      RODRIGUES, E. T. and HAN, J. H., 2003: Intelligent packaging. In: Heldman, D. R. and Moraru, C. I. (ed.). Encyclopaedia of Agricultural, Food and Biological  Engineering. 2nd edition, New York: Marcel Dekker, pp. 528–535. ISBN 978-1439811115

·      HAN, J. H., HO, C. H. L. and RODRIGUE, E. T., 2005: Intelligent packaging. In: Han, J. H. Innovation in food packaging. UK, London: Elsevier Academic  Press, p. 138–155. ISBN 978-0123116321.

·      Gontard, N. Active packaging for food processing and preservation. In: International Congress on Engineering and Food: ICEF 9, 7e11 March 2004, Montpellier, France.

To be continued..............