FOOD8110 Advanced Food Chemistry

Demonstrate your understanding and interpretation of your laboratory experimental results and also how they relate to what is known in the literature. 

Answer:

Introduction

This experiment is based on the premise that emulsifiers have an effect on a chocolate coated product. To this end it seeks to investigate these effects if any. It also attempts to measure the viscosity of melted chocolate commodities and further tries to explore the implications of addition of various colours and flavours to chocolate (white chocolate). 

Aim/Objectives 

Apparatus

Method/Proceedure. 

Emulsification and enrobing.

Two ceramic bowls containing 200g chocolate each were prepared. The bowls were the labelled as ‘Emulsifier’ and ‘no emulsifier’. The chocolate bars were melted at intervals of 30 seconds using microwave. Stirring was done between the heating sessions. Heating was done for about 1.5 minutes, taking care not to overheat the chocolate bars as this could change the consistency and make the bars very firm. Upon melting of the chocolate in both bowls to a similar consistency, 1.0ml of emulsifier was added to the bowl labelled ‘emulsifier’. The bowls of melted chocolate were then placed on a water bath to help keep the chocolate in the molten state.

Taking care not to allow water entrance into the chocolate mix as this would make it seize up, each biscuit was weighed, recorded and dipped vertically into the chocolate mix without the emulsifier such that the entire biscuit was covered with chocolate save for the held part. A spoon was then used to ensure full coverage of the biscuit. The excess chocolate was allowed to flow into the bowl for 30 seconds while removing the biscuit from the chocolate. The process was then repeated for chocolate with the emulsifier for the second piece of biscuit. The biscuits were then placed on pre-labelled baking paper and placed for 5 minutes in the fridge to allow for the cooling of the chocolate. Once cool, the biscuits were re-weighed and the percentage of chocolate in the final product calculated for both two cases. Each biscuit was broken into half and the total thickness of the biscuit and chocolate coating determined.     

Measurement of viscosity using the Brookfield viscometer.

A spindle was connected to the Brookfield viscometer. Samples for testing were then prepared. The spindle was then lowed into the sample such that the level of the surface of the sample was at the indention with the spindle shaft. The speed of the viscometer was then set at 50 rpm and the viscometer started. The Brookfield reading was then recorded. The process was then repeated for other additional foods with considerations to choose different spindles for various foods.

Results

Activity 1.

Activity 2.

Discussion

Chocolate without emulsifier produced biscuit with the most coating. Emulsifier made the biscuit chocolate coating to reduce in weight hence the final coated biscuit was of reduced thickness per biscuit. There was no taste differences found in the two biscuits. Texture differences were felt; emulsifier made the biscuit a bit coarse.

Plain biscuits is $0.80/ kg and the cost of chocolate is $5.00/ kg;  The cost of producing a kilogram of each of the two batches is thus;

Weight of plain biscuit= 15g  Weight of chocolate coating =26.5  Weight of chocolate biscuit =41.5

 Cost per kilogram - Chocolate enrobed biscuit $ / kg = (15/41.5 x 0.8)+(26.5/41.5x 5)=0.289 +3.193=3.5 $ / kg.

Cost per kilogram - Chocolate with emulsifier enrobed biscuit =(15/34.79 x0.8)+(19.79/34.79x 5) =0.345+2.844= 3.2 $  / kg    

Calculate how many biscuits can be fitted in a packet ?

Number of biscuits chocolate coated = Length of packet (mm)/Average thickness of biscuit (mm) =42/ 1.9=22

Number of biscuits chocolate with emulsifier enrobed = Length of packet (mm)/Average thickness of biscuit (mm) = 42/1.5 =28

Length of packet=42mm (mm)Average thickness of chocolate coated biscuit biscuit=  1.9  

Number of biscuits – Chocolate enrobed Number of biscuits=22– Chocolate with emulsifier enrobed=28    

Work out how much a packet of the biscuits would cost

A packet of 22 biscuits costs = 22x3.5=77$

A packet of chocolate coated biscuit with emulsifier of 28’s costs = 28x3.2=89.6$ 

  

  

A viscosity of 50 and below  is considered ‘low’ viscosity good for dipping purposes. Above 50 is considered ‘high’ viscosity. Hence the viscosity of the molten chocolate is high.

Conclusion and Summary

The experiments is a useful indicator of costs of producing the chocolate biscuit as well as the individual costs of the ingredients i.e plain biscuit and chocolate. This can be applied industrially for development purposes.

References

Chocoley L.(2017). Understanding Viscosity of Chocolate. Chocolate 101. Retrieved from: https://www.chocoley.com/blog/resources/understanding-chocolate-viscosity/