2012 Cake and slice analytical program

Background

The majority of nutrient profiles for cakes and slices consumed during the 2011-12 National Nutrition and Physical Activity Survey (NNPAS) component of the 2011-13 Australian Health Survey (AHS) were developed using a recipe approach that took account of the typical ingredients and their relative proportions to calculate nutrient values in a food.

In June 2012, Food Standards Australia New Zealand (FSANZ) undertook a small analytical program for a selection of cakes and slices to obtain data on the moisture, protein, total fat, starch, sugars, ash and sodium contents to verify that the recipe approach used by FSANZ produced nutrient values close to the analysed values.

Sampling

FSANZ selected six types of commercial cakes and slices for analysis that were either reported as commonly consumed during the NNPAS or for which FSANZ did not have any recent analytical data. Eight samples were purchased for each type of cake or slice from a range of outlets representative of where they would be purchased by consumers, shown in Table 1.  All samples were purchased by FSANZ in Canberra on the 5 and 6 June 2012.

Table 1 Cake and slice types selected for analysis

Preparation and analysis

FSANZ weighed and photographed the samples before sending them to the National Measurement Institute (NMI) where they were received on 7 June 2012. For muffins and cupcakes the weight of each individual cake was measured. For banana bread, caramel slices and chocolate brownies, the density of each purchase was determined in addition to the individual slice weight. FSANZ also collected information on the proportion of cake to icing for the each cupcake.

The NMI homogenised and combined samples to form one composite sample for each type of cake and slice for analysis.

The NMI conducted the analyses at their Melbourne laboratories using methods of analysis that have been accredited by the National Association of Testing Authorities.

Results

FSANZ validated the NMI results using information from analytical results previously obtained by FSANZ and food labels (ingredient lists and nutrition information panels), where available.

As expected, all of the cakes and slices analysed were high in sugars and fat and contained amounts of sodium that indicated they contained added salt, salted butter or sodium-based leavening agents. Although fatty acid composition was not determined, available ingredient lists indicate the use of vegetable oils as baking fats.

For the complete set of results generated from this program refer to Table 2.

Updates to the food nutrient and measures databases

After comparing analysed nutrient values from the 2012 program to those estimated using a recipe approach, we found that analysed moisture values for banana bread, brownies, caramel slices and cupcakes were higher than recipe values and the analysed moisture value for muffins were lower. Analysed sodium contents were lower than current values for all foods except caramel slice.

FSANZ updated a number of cake and slice recipes to better reflect current product composition. The main updates focused on adjusting the:

• Weight change factor, which is an estimate of the moisture lost during baking and determines the moisture content for each food, so that the recipe moisture aligned with the appropriate analysed value. 
• Sodium content, by adjusting the amounts of salt and leavening agents (which contain sodium) in each recipe, so that final sodium contents were consistent with analytical data. 

Small adjustments were also made to the proportions of baking fat, sugar and flour in each recipe to match analytical data for fat, total sugars and starch.

Density data for banana bread, caramel slice and chocolate brownie and measures for individual slices, cupcakes and muffins were also added to the measures database.

Conclusions

The results of the analytical program filled some important data gaps and have given FSANZ an improved level of confidence about the composition of these commonly consumed cakes and slices. FSANZ confirmed that a recipe approach is an appropriate method of developing nutrient profiles for these foods noting that it was necessary to make only minor modifications to the recipes used to develop nutrient profiles for cakes and slices based on the data from the analytical program.

Table 2 Analytical results from the 2012 cakes and slices survey. Results are reported per 100 g of food.