Electronic Journal of Polish Agricultural Universities (EJPAU) founded by all Polish Agriculture Universities presents original papers and review articles relevant to all aspects of agricultural sciences. It is target for persons working both in science and industry,regulatory agencies or teaching in agricultural sector. Covered by IFIS Publishing (Food Science and Technology Abstracts), ELSEVIER Science - Food Science and Technology Program, CAS USA (Chemical Abstracts), CABI Publishing UK and ALPSP (Association of Learned and Professional Society Publisher - full membership). Presented in the Master List of Thomson ISI.
Volume 9
Issue 3
Food Science and Technology
Available Online: http://www.ejpau.media.pl/volume9/issue3/art-07.html


Piotr Konieczny1, Agnieszka Bilska2, Waldemar Uchman2
1 Department of Food Quality Management, University of Life Sciences in Poznań, Poland
2 Institute of Meat Technology, University of Life Sciences in Poznań, Poland



A dynamic development of rapid, instrumental analytical methods can be observed during the last years which make possible to evaluate both food products in final form as well as during processing process. Owing to that it is allowed to combine the information about composition and properties of item with its price, which influences consumer in their purchase decision, ready to pay for true quality of product. Some examples of analytical techniques based on near-infrared spectrophotometry and used for rapid chemical composition assessment of meat and milk products are given in this publication. Taking into consideration food distribution system, the water activity of food was indicated as one of the most important parameter, which can be quick determine by the use of different measurement instruments. However, it must be emphasized that the selection of specific analytical method is always affected by various factors, and first of all, depend on the current financial possibilities and material and technical conditions of the lab.

Key words: food products, rapid analytical methods, near-infrared spectrophotometry, water activity .

In modern food industry, especially operating in a market economy, it is necessary to continuously strive to assure high quality of offered products. At present the requirements faced by food producers include:

– constant assurance of good quality raw materials, additives and attractive packaging,
– on-going implementation of improved manufacturing methods and technology,
– development and practical application of a quality assurance system incorporating all units preceding the sale and consumption of a given final product.

Every food producer has to guarantee that quality and safety of their products meet specifically defined requirements. They need to be taken into consideration when constructing the management system of the plant or its modernization. A consequence of this must also be to ensure an appropriate logistic base facilitating a practical realization of such specified tasks.

One of the ways to provide an effective management system is to accurately monitor quality for each lot of the final product. However, at such an approach (“end point”), any deviation from the assumed parameters is signaled at the time when it is too late to make any corrections. Although an efficiently operating analytical laboratory makes such a solution possible, as a rule it is burdened with high costs of analyses and storage of products. In this case a decision to release a product onto the market will depend on the obtained results of analyses.

Obviously a better solution is to combine a possibly thorough analysis of raw materials and additives as well as final products with the control of selected essential parameters at individual stages of the manufacturing process. The deviations in the course of processing may then be promptly detected and corrected. For a food producer who monitors the so-called critical control points during the manufacturing process (HACCP), fast and relatively accurate analytical techniques constitute an important tool, guaranteeing the results are obtained as fast as possible. Efficiency of production may be improved, since the time of the product being released from the plant to the market is significantly shortened [3, 4, 5].

As it can be observed in practice, information on the composition and properties of the product purchased by the consumer may be linked with the price. A good example of such a connection between price and quality is the meat industry, where the final value of processed products is with increasing frequency dependent not only on the weight of the product, but on the contained components. An obligation was imposed on producers of meat products to e.g. define the standardized contents of meat (meat protein) and connective tissue. For other products, such as e.g. light cheeses, it has recently been attempted to establish prices based on calorie value. Such an approach requires appropriate methods and equipment for prompt measurement of parameters established for a specific sample of the product and not the mean value for the assortment. Thus the basis is to create the method – equipment – process system, which in real time (on line) would conduct necessary analyses, weigh the product sample, perform required calculations so that at the end of the production line the obtained information (contents of individual components and an adequate price) may be printed on the label of the final product. Then the consumer has the chance to consciously make a decision on the purchase of a product and pay for the actual quality of the product.

Rapid quality control of individual batches of consumer goods is particular important for the establishment of permanent cooperation between processing plant and trading networks. Trading companies organized as networks has become their main distribution channel for the producers of food products. Trading networks staffs as a separate part of trade & marketing departments are today creating in the majority of big food processing companies [11].

Efficient analytical control in food-processing industry is critical factor for food product safety in the supply and distribution system. Examples presented in this study are an attempt to illustrate progress made in the technique of food analysis.

As it has been mentioned, in modern industrial practice various attributes of manufactured foodstuffs are routinely assessed, including their chemical, sensory, mechanical or microbial characteristics [9, 12]. Good examples concerning the possible application of rapid analytical methods for the widely understood quality control are supplied e.g. by meat industry. Rapid process chemical analysis frequently requires the determination of the chemical composition of the processed material, e.g. contents of fat, protein and water. Reference methods in this respect are labour-consuming procedures and obtaining the final result practically takes more than ten hours. Although at present some plant laboratories are using advanced equipment, making it possible to analyze a large number of samples in the automatic or semi-automatic system, even then the analyses take too long.

The possibility of a routine quality inspection of the above mentioned food components, also on the production line (on line), is offered nowadays by infrared spectrophotometry. From the practical point of view the most important are measurements in the so-called near infrared (NIR), defined as the region of light having wavelengths between 700 nm and 2500 nm. Commercially available spectrophotometers for routine infrared analysis available in Poland differ in their design, degree of computerization and obviously in their price.

To ensure effective operation these devices require calibration performed on the basis of a simultaneous analysis of samples using conventional chemical methods and the extensive calibration data base, including a library of spectra and chemical assays is a necessary pre-condition for the application of this method in industrial practice [5].

Infrared spectroscopy may play a crucial role in the analysis and process control during the manufacture of numerous other food products. This technique offers huge possibilities in the determination of contents of water, protein, fat and lactose in a wide range of dairy products, e.g. drinking milk, dairy concentrates, cream or different types of cheeses. Many of these products are emulsions, from which sampling for the purpose of conventional chemical analyses is rather difficult. The NIR equipment generally works very fast, is easy to operate and in terms of its accuracy yields similar results to reference methods, according to which it is calibrated. NIR does not require at all or if any – only a slight preparation of samples and it is not necessary to use chemical reagents [1, 8].

Analysis of chemical composition in dairy industry may nowadays include a much more extensive range of information on the properties of the processed material or product. Table 1 presents the most common measurement systems used to determine contents of different compounds in processing procedures in dairy industry.

Table 1. Application examples of rapid analytical methods in dairy products processing




Active acidity (pH)

Ion-selective electrode, field effect transistor

On-site fermentation, washing and disinfection

Water content

Near infrared spectroscopy

Production of cheese and milk powder

Fat content

Near infrared spectroscopy

Fat standardization, quality inspection of dairy products

Protein content

Near infrared spectroscopy

Protein standardization, quality inspection of dairy products


Flow injection analysis, receptor analysis, near infrared spectroscopy

Monitoring of fermentation, quality inspection

Lactic acid

Flow injection analysis

Monitoring of fermentation

Flavour compounds

Rapid mass spectrometry, electronic nose, electronic tongue, spectroscopic techniques, selective mass spectrometry

Process control, quality inspection, washing and disinfection

Residues, impurities

Rapid mass spectrometry, electronic nose, electronic tongue

Process control, quality inspection, washing and disinfection


Thermal resistance, pressure drop

Manufacturing processes


Receptor analysis, optical measurements

Burnt powder particles

Washing, disinfection

Conductivity, electronic nose, electronic tongue, receptor analysis, spectroscopic techniques, selective mass spectrometry, ion-selective electrode

On-site washing and disinfection

In most food products one of the main factors determining their quality, especially their shelf-life, is the presence of water. Its content may fluctuate throughout the whole manufacturing process. For this reason the determination of water content belongs to the basic elements of ongoing quality control.

In order to shorten the commonly known classical drier method some improvements are applied, consisting in the coupling of infrared driers with an analytical balance (the so-called balance driers). They are accurate laboratory devices for prompt (from 2 to 320 min) determination of water content in small samples, usually from 3 to 5 g. Drying temperature may be programmed and regulated automatically. The result is also given numerically in per cent, after complete drying of the sample. Assay results with the code of the sample, date and the time of the assay, may be collected in a data base or immediately printed in the form of a report with a specific format. Such apparatus is produced by several manufacturers and it needs to be pointed out that it is relatively simple to learn how to operate it.

From the point of view of food distribution and its organization, an even more significant role than water content in products is played by the awareness of its connection with shelf-life of foodstuffs. Water content determines the possible development of microflora hazardous for humans, although food products with identical water contents may considerably differ in their susceptibility to spoilage. It was observed more than fifty years ago that most parameters determining the quality and shelf-life of food are not connected with total water content, but its activity [7].

The range of physical, biochemical, chemical and microbiological changes occurring during storage of food may be reduced considerably by decreasing water content or cauising the transition of free water to bound water, unavailable for the above mentioned changes deteriorating the quality of food. The most frequently applied methods include drying, smoking, freezing and adding substances exhibiting osmoactive properties, especially sugar or table salt [10].

The practical role of this quality parameter important for each food product is growing along with the development of methods of food sales, with the expanding network of self-service shops and supermarkets, and in any other place where commercial portioning and packaging of products takes place. Prompt measurement of water activity yields reliable profits in food retail industry, which may be illustrated again by the example of meat industry. On the basis of their aw values and concentrations of hydrogen ions meat products may be classified into the following groups:

Thus the possibility to determine water activity in food products fast and easily is essential. Measurements of water activity may be taken using different methods, including at present those with the application of different types of meters [2, 6]. For several years now stationary as well as portable convenient sets for measurement of water activity are offered by a few companies operating on the Polish market.

Examples given above are for obvious reasons only a fragment of a long list of instrumental solutions offered in food analysis. It needs to be again emphasized that an appropriate application of rapid food analysis methods may be important not only in terms of quality control, but also marketing, and may bring tangible effects to the plant which has implemented them.

Summing up the above considerations it also needs to be added that food analysis including all types of chemical, physical, microbial methods may be extensive, very fast, but also very expensive. The decision which analytical technique should be applied depends first of all on the assumed objective, the number of analyses, required accuracy, frequency with which the analyses are to be performed and primarily on the material and technical, and - last but not least – on the financial status of a given laboratory.


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  2. Ćwiertniewski K., Przybył H., Egierski K., 2004. Oznaczanie aktywnosci wody kiełbas typu salami [Determination of water activity in salami type products]. Gosp. Mięs. 6, 10-12 [in Polish].

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  6. Lewicki P.P., 1989. Właściwosci wody w produktach spożywczych [Properties of water in food products]. Semin. Mater. Wyd. WSM, Gdynia [in Polish].

  7. Lewicki, P.P., 2000. Znaczenie własciwosci fizycznych w projektowaniu jakosci produktów spożywczych [Significance of physicals properties on the designing of food products]. Mater. Int. Sci. Conf. Agrophysics in testing agricultural materials and products, Polskie Towarzystwo Agrofizyczne, Cracow [in Polish].

  8. Pikul J., Konieczny P., 2004. Pomiary jakosci produktów spożywczych bezposrednio na linii produkcyjnej na przykładzie przemysłu mleczarskiego [Quality assessment of food products directly on production line based on dairy industry]. Mater. 5th Int. Semin. Food Quality and Safety, 25-27.10.2004, Poznań, 112-127, [in Polish].

  9. Pruska-Kędzior A., Kędzior Z., Bera E., Hryciuk K., Golińska-Krysztofiak J., 2005. Application of dynamic rheology methods to describe viscoelastic properties of wheat gluten. EJPAU, Food Sci.Technol. 8 (2) www.ejpau.media.pl.

  10. Sikorski Z., 2006. Chemia żywnosci. Skład, przemiany i własciwosci żywnosci [Food chemistry. Composition, metabolism and properties of food]. Wyd. WNT, Warsaw [in Polish].

  11. Tubis A., 2006. Organizacja dostaw do sieci handlowych, współpraca producentów z dużymi detalistami [Delivery organization to trading networks. Cooperation between manufacturers and big retailers], Logforum 2, 1, 6, [in Polish].

  12. Wojciechowski J., 1978. Aktywnosć wodna [Water activity]. Gosp. Mięs. 1, 20, 3, 25; 4, 24; 10, 24 [in Polish].

  13. Zawirska-Wojtasiak R., 2006. Chirality and the nature of food authenticity of aroma. Acta Sci. Pol., Technol. Aliment. 5 (1), 21-36.

Accepted for print: 08.08.2006

Piotr Konieczny
Department of Food Quality Management,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 31, 60-624 Poznań, Poland
email: pikofood@au.poznan.pl

Agnieszka Bilska
Institute of Meat Technology,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 31, 60-624, Poznań, Poland
phone: (+48 61) 846 72 61
email: abilska@au.poznan.pl

Waldemar Uchman
Institute of Meat Technology,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 31, 60-624, Poznań, Poland
ph: (+48 61) 846 72 61
fax: (+48 61) 846 72 54
email: waluchm@au.poznan.pl

Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.