All over the world, test baking is the most common procedure followed by mills for determining the baking quality of their flour. Test baking is also the method used by bakeries in their quality control laboratories.
Ingredient companies employ the same methods in order to determine the quality of their products.
Urban Girhammar reports.
Baking quality depends on a number of factors. Most of these factors, however, are found to be positively correlated to loaf volume. The loaf volume of bread, perhaps along with the shape of the loaf expresses the baking quality of the flour related to many chemical, physical and sensory characteristics such as the protein quality, enzyme activity and damaged starch.
Consequently measurement of loaf volume has been universally recognised as indicative of baking quality. At present, loaf volume is measured using the seed displacement method, but this method is primitive, inaccurate, tedious and laborious.
The Bread Volume Measurer, BVM-3, by TexVol Instruments overcomes many of the shortcomings of seed displacement. It uses an ultrasonic sensor and a computer program to determine the volume, height and two width dimensions of baked food. The instrument is PC-operated through simple-to-use software.
Replicas of baked products were made out of polyurethane: 10 small rolls (A1-A10), 10 larger rolls (B1-B10) and two loaves (C1-C2). The volumes of these were determined by water displacement. Each roll and loaf was measured three times.
Using the seed displacement method the 10 small rolls were all measured together three times. The larger rolls were measured three times in two groups of five. Each loaf was measured three times.
Each roll and loaf was measured 10 times at both 10 and 60 seconds in the BVM-3.
Three pizzas (P1-P3) were measured 10 times at 60 seconds. The pizzas were only measured using the BVM as it is not possible to measure them in any other way.
As shown in Table 1, the accuracy of the BVM- 3 is much greater than that of seed displacement. The latter has a variation of 3.5 11.1 per cent from water measurement; the BVM (60 sec) comes within 1per cent. Accuracy is difficult without precision. Precision, however, does not ensure accuracy, but with correlation it does give accuracy. Tables 2 and 3 demonstrate that precision is achieved even with 10 second measurements. The repeatability of the measurements at both speeds is well within the level of acceptability for useful measurements. With precision it is possible to correlate the results to achieve accuracy. The software allows the user to input specific correction equations.
Hence, even results measured at 10 seconds will show accurate results. As shown in Figs. 1 and 2 the volume of the rolls measured using the BVM-3 is in close agreement (R2=0,999) with the values obtained using the water displacement method. This applies to both 10 and 60 second measurements.
The BVM-3, with its non-contact operation has the ability to measure objects that due to their texture or size was not possible with seed displacement. As shown by the statistics from the measurement of the pizzas, the repeatability of the results makes comparisons meaningful.
Over and above its ability to measure accurately, the BVM-3 has many advantages over current methods. The ability to measure accurately at 10 seconds implies considerable time savings, especially as all the data is automatically stored in a database file. This is achieved by correlating the results of 60 and 10 second measurements. The formula is then inserted in the software. Different products require different correlations. The accuracy of the data and the fact that it is not operator dependent makes it possible to compare results between different locations. Another important feature of the instrument is that it produces a rotatable diagram of the measured object. p
Enquiry No 22
Urban Girhammar is a consultant. TexVol is based in Viken, Sweden. www.texvol.com
