Overcoming the complexity of monitoring natural produce

As consumers become more concerned with quality, the amount of research is increasing into product authenticity to assure buyers that beverages contain the ingredients they are expecting. Eric Russell reports.

In the Netherlands, The Netherlands Organization for Applied Scientific Research (TNO) Nutrition and Food Research division says that, since the 1970s, consumption of fruit juices has increased substantially.

This has resulted in a growing need for clear and uniform methods of assessing their quality and purity because drinks are subject to continuous technological innovation and research. This makes scientific support vital, especially where specific requirements are stipulated for the product.

Following the adoption of the European directive 96/77/EEC, it was left to the EU fruit juice industry to decide what were the chemical characteristics of authentic juices. But, in the absence in the EU directive of guidelines on the methods that could or should be used in assessing what a real or authentic juice consists of, TNO has developed its own authenticity criteria. These compare with developments elsewhere in Europe. France has its AFNOR standards, for example, while Germany has its RSK standards.

The great variations in the composition of natural produce make monitoring authenticity a complex business. It means that the criteria selected to define an authentic juice cannot be seen as absolute. Today, TNO laboratories are specially equipped to test the purity of fruit juices and nectar in particular and their expertise provides the basis for the organisation's international reputation.

Visual quality

But the visual quality of beverages is also important. Products not only have to look inviting, they have to meet consumers' predetermined perceptions. This is an important consideration amongst beer drinkers, where the head on a glass of beer is always critically commented on.

Many brewers have used the services of TNO to investigate beer foam quality as the volume and stability of the head are the first characteristics observed by the consumer and strongly contribute to their appreciation of the product.

TNO offers trouble-shooting and consultancy in this area. A systematic, step-wise approach in case of beer foam problems enables rapid discrimination between the possible causes of foam instability, such as low protein quantity, insufficient protein quality and presence of contaminating detergents, lipids or fatty acids.

The organisation has a long tradition in development of analytical tools for beer foam quality and says its NIBEM foam analyser is a widely used and well known example.

Such tools can not only be used to determine beer foam protein quality, but also to monitor foam proteins throughout the malting and brewing processes. The effect of changes can be studied during these processes by altering different parameters with the aim of maximising the amount of foam-positive proteins in the beer.

TNO is an independent R&D organisation with a staff of some 4500 and a total annual turnover exceeding US$400million. TNO Nutrition and Food Research is the largest institute within TNO, with a staff of about 800. Founded in the 1940s, TNO has become a unique facility involved in technological, biotechnological, analytical, nutritional and toxicological research. Worldwide partners include the food, feed, pharmaceutical and biotechnology industry as well as chemical, pesticide and personal care producers.

Drinking analysis

At Strathclyde University in the UK, the Department of Bioscience has developed a sensing technique that collects chemical substances from within the mouth cavity during drinking and eating. Known as the buccal headspace technique, volatiles are sampled via the consumer's nose.

During drinking, products in the mouth undergo temperature changes, are mixed with saliva and the pH might change. Flavour compounds are released to pass to the taste receptors in the tongue and the olfactory receptors in the nose. The sensations from all the senses are then integrated in the brain to produce the total impression of the food. Samples taken from within the mouth provide the most accurate material to work on for analytical purposes.

Dr John Piggott, of the Bioscience department, says work on distilled alcoholic beverages has provided new understanding of the maturation process. This includes the ways in which changes in the non-volatiles present in the beverage as a result of maturation in wooden casks cause changes in the volatility of aroma compounds already present in the liquid.

So the improved smoothness of matured beverages such as whiskies and brandies is partially due to changes in the structure of the aqueous ethanol solution, which determines the volatility of the aroma compounds and therefore the flavour of the beverage.

This work has been extended to fortified and table wines, and it has been shown that the change in structure of ethanol-water systems which occurs at approximately 17percent v/v ethanol has major implications for the flavours of these products.

Sensory analysis

Research methods used include sensory analysis, primarily descriptive methods and free-choice profiling, aimed at studying the natural variation in flavour of foods and the changes caused by processing.

Time-intensity methods are also useful for studying the dynamics of flavour release from foods as they are consumed, and progressive profiling has been developed to monitor changes in texture as foods are chewed.

Physico-chemical methods include headspace concentration and gas chromatography, largely used for analysis of volatile aroma compounds with either flame ionisation or ion trap detection, high pressure liquid chromatography for analysis of non- and less-volatile flavour compounds, and Instron UTM for studying the mechanical properties of foods. Gas chromatography with olfactory detection (sniff-port) is also used as an aid to identification of aroma compounds.

Multivariate data analysis techniques including principal components analysis (PCA) and partial least squares regression analysis (PLS) are used to aid interpretation of data and modelling of relationships between data sets.

Dr Piggott has also been involved in the development of a vocabulary of terms for the sensory evaluation of dessert port wines. It was found that only experienced individuals tended to buy premium ports but as these are of considerable commercial importance, the vocabulary was designed to open up the market to a wider range of consumers.

New coffee system

The popularity and demand for single-serving roast and ground coffee products continue to grow on a worldwide basis says Molins ITC Machines, which has come up with a novel and effective single-serve solution called Cafusa.

It says that consistent quality, convenience and speed of preparation are the main factors driving demand in both the retail and food-service markets.

This has driven the development of Cafusa, a single-serve coffee bag with a difference. It combines the quality of flavour and infusion achieved with a more traditional drip filter or cafetiere with the speed and convenience of instant coffee, but without any grains left behind.

The coffee bag comprises a double-chamber infusion filter attached to a novel card tag that securely supports the bag in a cup or mug. By squeezing the tag, the bag size can be adjusted to fit snugly in many different cup sizes and styles. As well as providing a stable method of locating the bag in the cup, the tag also provides an opening through which hot water is poured directly onto the fresh ground coffee below.

These factors provide the perfect circumstances for a very rapid infusion and maximum flavour. So quality, freshly ground coffee can be made in almost the same time as it takes to make instant coffee.

Each bag contains approximately 40 ground coffee beans, the same measure as that of a typical espresso. Key to the performance of the new coffee bag is the patented Pour-Thru technology utilised in the design.

Each coffee bag is individually sealed and nitrogen gas-flushed in a foil laminate sachet. The card tag is designed to fold over in the sachet, which prevents coffee from escaping into the sachet during handling or transit. Residual oxygen levels of less than 1percent are achievable on the machine, thereby giving a typical shelf life 12 months. The sachet also serves as a useful container in which to dispose of the used coffee bag.

A major advantage of Cafusa is its flexibility. The size and design of the bag can be adapted to suit individual markets and tastes. For example, a smaller bag size with tapered sides may be required for European markets, whereas a larger bag may be required for the USA and Canada.

Building on its success in the UK, Molins ITC Machines are now looking for partners to market Cafusa worldwide.

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