Waste Less, Feed More: Mathematical Modelling Serves to Combat Food Waste

For the first time, a novel approach of addressing food wastage from 2-level supply chain (consumer and retailer) is introduced as previous model only addresses from a single level.

Did you know the amount of food wasted annually is approximately 1.3 billion tons, surprisingly this figure corresponds to one-third of all food production that feeds the entire human population? Are you secretly guilty for contributing to this massive number? How did we manage to waste so much food?

At the retailer level, food waste refers to food that are disposed as they become stale or unsalable beyond the expiry date. On the other hand, at the consumer level, food waste refers to food for household or personal consumption that is discarded when unwanted or expired.

Food wastage is especially prevalent in developing and developed countries, as income level thus purchasing power increases. At the consumer and retailer level, food wastage is largely due to poor consumption and purchasing habits and the wide availability of product choices. Undeniably, consumers are attracted to the discounted prices offered when purchases are made in larger quantity and ended up buying more than what they need. Are you one of them? Owing to the dynamic nature of consumer businesses, it is difficult for proprietors to predict consumer’s demand, thus food products are order in excess. This means that perishables with short shelf live eventually goes to waste when unsold or unconsumed. Unfortunately, food wastage entails other problems which affect the environment and possibly the economy. With greater waste, more landfills and manpower would be required to dispose them. Environmentally, methane generated from rotting food aggravates the greenhouse effect more than CO2. More significantly, tackling food wastage is vital for ensuring food security. As such, we will look at how stochastic mathematical modelling can potentially reduce food wastage.

While previous research and models are similarly targeted at reducing food wastage, a glaring difference lies in the failure of those models to capture the relation and interaction between the dual-level supply chain (consumer and retailer). Previous model focused on strategies that address from either the consumer or retailer supply chain separately. One model formulated the prime time for businesses to donate their leftovers to charitable organisations with the aim of minimizing the cost of wastage while optimizing the benefits to recipients. Considering the quality and extent of decline of perishable food, another model formulated the price for selling perishable food items at cheaper rates while minimizing compromise on sales returns. It is obvious that the focus is only one level supply chain. However, if consumers continue to contribute food waste, is one level supply chain strategy really effective? Imagine a fish tank consisting of two holes, does covering one hole stop the leakage or the fish would eventually die as water still leaks from the other hole? Clearly, we need a strategy that address multiple sources of food waste.

The 2-level supply chain mathematical model introduced by Dr Po-ngarm Somkun of Naresuan University, addresses both the consumer and retailer aspects of food wastage. The team led by Dr Po-ngarm Somkun, conducted a survey compromising 330 participants to determine the impact on quantity of food waste in which social factors (income and gender) and food types are accounted for. To study consumer behaviours, participants were asked to rate their behaviour (highly agree to highly disagree) which gives indication of positive response (e.g. use of shopping list) or a negative response (e.g. overbuying during promotions). In the case of businesses, interview was conducted with owners to determine the quantity of food wasted based on its type, brand and sizes. Subsequently, these data are translated into the mathematical model to investigate the impact of the size of a unit sale (varying the size between 50 and 550grams) on the unit size of total food waste.

As a result, the model established a link between the size of unit sale and the total food waste. This allows an ‘ideal’ size of unit sale to be derived and adopted by businesses and consumers respectively such that the total food waste would be kept to the minimal.

Dr Po-ngarm Somkun acknowledges that not all food products sold in the market are highly perishable, with some having long expiry dates. However, this model which assumes shelf life to be approximately one day, still closely depicts fresh food (e.g. meat and vegetables) and dairy products that are most perishable and regularly consumed in our daily life. For sure, one can expect improvement in inventory management practices and she is hopeful that the model may be extended to replenishment planning.