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 | | UPPER CRUST (INTERNATIONAL FOOD INGREDIENTS MAGAZINE APRIL/ MAY 2008) | | | CMP | | 19/05/2008 | | | Jo Smewing, applications manager at Stable Micro Systems, explores current physical characterisation methods designed to ensure the textural quality of today’s bread products
Bread is one of the oldest foods. The word itself has such cultural gravitas that it is often used as a metaphor for basic, general necessities. With snack and bread products currently dominating the top five grocery brands in the UK (AC Nielson, March 2007), and the bakery market set to grow by 12.6 per cent by 2011 (Datamonitor, August 2007), bread clearly still holds its centuries-old position as a dominant, staple food source.
Just as mankind has evolved, so has bread. Today, the market for bread is diverse and highly competitive, with thousands of intrinsic and superficial variations presenting consumers with an abundance of alternatives. One thing, however, remains constant – the fresher the bread, the more appetising it is, and texture is a key factor in this perception.
End product texture and freshness perception can be predicted through the analysis of dough characteristics. It is therefore essential that manufacturers invest in thorough physical characterisation during the earlier stages of production, to ensure efficiency and, most importantly, customer satisfaction.
Born and bread
Dough’s formulation is the prime determinant of its physical and behavioural traits as a finished bakery product. Many of the textural properties of bakery products depend on the earliest steps in the dough making process, notably the interactions between the main ingredients - flour, water, yeast - and air. By the time the dough has been mixed, its rheological characteristics are already determined.
It is essential that the optimum formulation of ingredients be achieved at the earliest stages of the manufacturing process. The use of texture analysis at this point can help guarantee the ideal dough texture, minimising the risk of unnecessary financial and material losses for the manufacturer, retailer or consumer. In a market where competition is fierce and brand loyalty high, there is no room for inferior quality.
As pieces of dough are separated and rounded, the balance of their viscoelastic components is critical. A dough that is too elastic is awkward to manipulate and so will often result in a misshapen end product, which will be rejected by the manufacturer. Likewise, a dough that is too viscous will not hold the desired end structure.
Resistance to extension and extensibility are important indicators of bread dough quality, and assessment of these characteristics can give a good suggestion as to how well a dough will react to the baking process. By expanding the dough through volume displacement of air, it’s possible to measure pressure during inflation, as well as the volume of the dough bubble at burst point. This allows certain textural properties to be quantified.
Traditional physical characterisation methods – such as the AACC standard – require large quantities of dough and are time consuming. This can make them impractical. However, Stable Micro Systems’ Dobraszczyk/Roberts Dough Inflation System has the ability to test smaller sample sizes, recreating conditions similar to the strain experienced around a slowly expanding gas cell. The test’s ability to analyze small samples make the instrument of additional interest to research and wheat breeders where only small flour samples can be obtained.
A sheet of dough is inflated by volume displacement of air, inside a customised temperature chamber, which can inflate it in temperatures of up to 60ºC. This chamber houses samples during their pre-test equilibration period, as well as providing a controlled temperature environment for more realistic assessment. The pressure and volume of the dough bubble are measured during inflation, and can subsequently be used to calculate such parameters as the strain hardening index of the dough. This offers a precursory warning of any potential deformation in the dough, allowing manufacturers to predict product anomalies and consequently eliminate them.
Sticky situation
Another important predictor of finished product quality is the stickiness of dough. This particular parameter is notorious in the bakery industry for causing time delays and wastage, when not properly controlled. Factors affecting this characteristic include excess water, overworking, too much or too little flour and enzymatic imbalances.
If a dough is too sticky, it is problematic to work with and cannot be easily removed from the mixer or rounder. Equally, if it is too dry, the dough will not be formed properly by the rounder and the desirable crumb structure cannot be created. A very delicate balance must be achieved in order to bind any layers that would otherwise create large holes while, at the same time, maintaining a firm product structure.
The assessment of dough stickiness prior to bulk preparation is a definite advantage to manufacturers wishing to save time and money, as well as create a high quality end product.
Stable Micro Systems’ Chen-Hoseney Dough Stickiness Rig is designed to analyse the stickiness of dough at the mixing, dividing and rounding stage. The employment of this test prior to bulk preparation can help identify weaknesses, so that any necessary processing or formulation adjustments can be made. A perspex cylinder probe with a uniform surface applies a measured amount of force to the dough sample for a specified time. After this time, the probe is withdrawn quickly from the dough and the force to separate the probe from the dough is measured. A high force indicates that the dough is very sticky, whereas a dough with no sticking qualities will record a very low force. Manufacturers can use the results to help optimize dough formulation by finding the ideal level of adhesion.
Assuming that all of the necessary characteristics have been considered by manufacturers prior to the bulk preparation and baking processes, a perfect loaf of bread should ensue. When considering the consumer, however, the most important textural assessment is that of the finished product. The quality of a loaf during its shelf life is a vital consideration.
The springiness of a loaf is something that consumers will universally assess when choosing which one to buy. The springier the loaf, the fresher it is perceived to be. Accurately quantifying something apparently so subjective may seem impossible, but advances in physical characterisation technology have enabled manufacturers to monitor even this – the most crucial assessment of all.
Stable Micro Systems’ revolutionary Bread V Squeeze attachment sees the recreation of a test performed by consumers in everyday life. ‘V’ shaped rounded fingers, positioned at an angle to represent the typical squeezing action, are attached to the arm of the texture analyser to produce a repeatable, standardised version of the consumer’s test for freshness. The force taken to compress the loaf is measured, providing an indication of loaf springiness, and therefore freshness. The lower the force and higher the springiness, the “fresher” the loaf. A compression test may be performed on packaged or unpackaged, sliced or unsliced loaves due to the non-destructive nature of the attachment. This method also requires no sample preparation.
With fierce competition and fast-paced product innovation, the bakery industry must constantly strive to improve quality. The diversity of products available serves to make categorisation within the sector increasingly ambiguous. Just as traditional ways of measuring the market with generalised overviews are now inadequate, so are generalised physical characterisation methods.
Controlled, targeted testing not only provides accurate end product quality assessment but can also demonstrate how dough will react to further processing during preparation and baking. For bakery manufacturers, the necessity for repeatable, scientific analysis is vital in terms of achieving maximum profitability in this ever-evolving industry. Texture analysis will ensure that only the highest quality products appear on supermarket shelves, which is good news for manufacturers and consumers alike.
l www.stablemicrosystems.com | |
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