Adapting products is tricky. According to the concept of "value engineering" new product development must balance the quest for cost reduction with the functions of taste, form and packaging. They all affect product preference. The challenge is to ensure that cost reduction does not result in loss of function or customer dissatisfaction. So, if a bar loses its straight edges in favour of curves – as happened with Cadbury Dairy Milk in 2012 – any loss of substance (the bar shrunk from 54g to 34g) should be compensated for by improved mouth feel or taste experience.