Volume Measurements on Frozen Products

Dr J. Purhagen

Perten Instruments, Helsingborg, Sweden
Department of Food Technology, Faculty of Engineering, Lund University, Sweden
jpurhagen@perten.com

Introduction

As the market for frozen bake-off products increases, more routine quality control measurements are required to ensure the consistency of the products. Quality control measurements can be performed on both the ingredients and at different production stages. Ingredients can be tested for instance by using a Falling Number instrument and Rapid Visco Analyzer (RVA) (AACC International, Crosbie & Ross, 2007), while semi-baked products and finished products can the tested for volume and texture (AACC International, 2014, Bourne, 2002).

Until recently, there were no standard methods for volume measurements, only guidelines (AACC International, 2001). The guidelines method derives from Archimedes principle (Heath, 1897) but instead of using water as a displacement medium it uses seed. Due to the physical contact between the seeds and the product, this seed displacement method is not suitable for sticky, crispy or soft products such as pasties. In October 2014, a new AACC standard method for volume measurements was approved (AACC International, 2014). This method uses laser topography to measure the volume of the products, which means that sticky, crispy and soft products can also be measured without anything touching the product besides the sample holder.

The aim of this study was to see how well the new AACC-standard method for volume measurements, method 10-14.01 (AACC International, 2014), would work on both frozen and ready baked bake-off products.

Material and Methods

Two types of bake-off products were used in the test, cinnamon roll and Danish pastry. The products were measured in both frozen and ready-baked state. Four samples of each product were measured in triplicate using a BVM-L100 (Perten Instruments, Sweden). This BVM-model corresponds to the BVM 6610 mentioned in the AACC-standard method. The test duration time was set to 60 sec. and the support attachments used were flat supports, rectangular shaped with the dimensions 15x40mm and 15x70mm for the frozen products and the baked products respectively, Figure 1. The samples were placed horizontally on the support, Figure 2. This position was chosen because of the character of the products. The baking was performed in an industrial oven (SelfCookingCenter 5 Senses, Whitefficiency, Rational AG, Germany). For the Danish pastries, the pastry program of the oven was chosen, while the cinnamon rolls were baked at 200°C for 13 min.


Figure 1: A – 15 x 40 mm, B – 15x 70 mm.


Figure 2: A–C sample set-up of the frozen products, D–E sample set-up of baked Danish pastry.

Results and Discussion

The mean results for the volume measurements are displayed in Table 1. These mean values and standard deviations were calculated on four different samples, and each sample was run in triplicate, i.e. 12 measurements. The standard deviation within each sample for the three measurements was 0.0.

For the frozen products it can be seen that the Danish pastry samples gave smaller standard deviations and were therefore more homogenous in size compared to the cinnamon rolls. It can thus be said that the production of the Danish pastry bake off at the manufacturer has a better reproducibility. Furthermore, the cinnamon rolls only had a significant increase in volume. The height and diameterMAX gave the same variations both before and after the baking. This could depend on the samples increasing differently during baking. Some samples might have increased in height and others in diameter (i.e. width or depth). The 3-D graphs for the cinnamon rolls before and after baking can be seen in Figure 3.


Figure 3: 3-D graph of cinnamon rolls, A frozen and B baked.

Table 1: Volume result displayed by mean values and standard deviation.

Cinnamon Roll 

Danish Pastry  

 

Frozen

Baked

Frozen

 Baked

Volume (ml)

104 ± 4.1

131 ± 4.3

84 ± 1.1  250 ± 24.4

Height (mm)

32.8 ± 0.75

33.5 ± 1.73

25.5 ± 0.52

 45.5 ± 5.32

Diameter MAX (mm)

95.5 ± 4.08

96.8 ± 4.00

100.0 ± 1.95

 117.3 ± 2,39

As seen in Table 1, the Danish pastries displayed a large increase in both volume and size dimensions after baking. However, the variation between the samples became very large, giving large standard deviations. In order to see how the volume for each sample was affected by the baking, the individual increase in volume was calculated, Table 2. The values are mean values of the triplicates with standard deviation of 0.0. It can be seen that the increase in volume for the cinnamon rolls was relatively equal between the samples (24–27%), however, the increase for the Danish pastries differed significantly between the samples (163–335%). This difference was also seen visually and in the 3-D graphs, Figures 2 and 4. The filling (seen in the frozen samples) of samples 1 and 2 were blown to the edge of the samples by the oven fan and were thereby preventing the dough from increasing in that side of the sample. For samples 3 and 4, the filling was maintained in the center of the product. It is therefore clear that the placement of the samples within the oven is important.

Table 2: Individual volume results.

Cinnamon Roll 

Danish Pastry  

 

Volume
(ml) 

Increase Vol (%) 

Volume (ml)   Increase Vol (%) 

 

Frozen

Baked

 

Frozen

 Baked

 

Sample 1

109

135

 24

84 248  195

Sample 2

105

132

 26

84

 221

 163

Sample 3

98

124

 27

82

 255

 311

 Sample4

 104

 132

 27

 85

 285

 335


Figure 4: 3-D graphs of Danish pastry, A – frozen product, B – baked product sample 1, C – baked product sample 4.


Conclusions

The volume measurement worked for both frozen and baked products, giving very good repeatability for replicate samples (0.0 in standard deviation). Size measurements could differ slightly depending on the set orientation of the 3-D graph after each measurement. The 3-D graphs displayed the variations seen visually. In addition, the measurements showed that the production of the bake-off products gave relatively equal products; however, the differences increased during the baking and were dependent on the position within the oven.

References

AACC International. Determination of Falling Number. Method 56-81.03.

AACC International. (2001), Guidelines for Measurements of Volume by Rapeseed Displacement. Method 10-05.01.

AACC International. (2014), Determination of Bread Volme by Laser Topography: BVM Method. Method 10-14.01.

Bourne, M. C. (2002). Food Texture and Viscosity (2nd ed.): Academic Press.

Crosbie, G. B., & Ross, A. S. (Eds.), (2007).The RVA Handbook: AACC International Press

Heath, T. L. (Ed.), (1897).The Works of Archimedes: Cambridge University Press