FOOD: Did you know…

You are probably aware that the current state of our world is critically dependent upon the integrity, functionality and efficacy of regional and global food systems, i.e. the entire chain from food production, processing, distribution all the way to the consumption of food. Yet, many food systems are under serious threat of being broken, thus exacerbating poverty, hunger and climate change.

A new level of leadership is required to ensure food security and sustainability in the world. At UNSW, with a view on personal health, planetary health and economic health, we have been significantly revamping our curriculum in the food and nutritional sciences to develop young professionals who can live up to this enormous challenge.

It is important to get a glimpse into challenges and miracles linked with food science and nutrition research both at the fundamental and applied levels.

At the UNSW, programs in Food Science & Technology and Nutrition are geared to develop young minds eager to build a sustainable world for generations to come.

1. Did you know that eating certain foods in combination can change how much iron you absorb?

In Australia it is estimated that 1 in 4 females and 1 in 30 males do not meet their daily iron intakes according to the Australian Bureau of Statistics, putting them at risk of iron deficiency. Being iron deficient can make you tired, reduce your ability to focus, and decrease your performance on the sporting field. Girls are more prone to deficiency than boys. You are all at an age when iron intake and absorption is important.

By adding some vitamin C (i.e., orange, capsicum, or broccoli) you can increase how much iron you absorb! However, eating a food with a lot of calcium in it (i.e., milk or yoghurt) can reduce how much iron you absorb.

2. Did you know fermentation makes coffee smell and taste better?

The coffee beans we use to make coffee are processed either by the wet or the dry method. In the wet process, coffee cherries are de-pulped, and the beans are submerged into water for 24-36 hours. In the dry process, the beans are usually dried by natural sun drying to about 10% moisture and then

de-pulped. In both the wet and the natural drying processes, microbial fermentation plays a vital role in determining the quality of the coffee beans and, ultimately, the coffee beverages. Both yeasts and bacteria are involved in the fermentation. These microbes utilize nutrients on the surface of the coffee beans, such as sugars and amino acids, and turn them into a wide array of compounds, known as metabolites. Many of these microbial metabolites are volatile, aromatic compounds which contribute to the overall taste and flavour of coffee beans and coffee beverages. Although we have a general idea of the importance of microbial fermentation to the quality of coffee, there are still many things we do not know about them. For example, we do not know whether it is the yeasts or bacteria, or both, that are more important to the fermentation process. And for yeasts and bacteria, we do not know which species and strains are contributing to coffee flavour.

3. Did you know spray drying turns liquid into powder?

Most of the food products we consume, such as bread, ice cream, instant coffee, juice, canned soups, processed cheese, and many others, contain ingredients that are often added as powders. Spray drying converts liquid into powder and is a crucial process in the food and dairy industry. A typical spray dryer has a nozzle which atomises the liquid feed into millions of droplets, which come in contact with hot air inside the drying chamber. The heated air evaporates most of the moisture from the droplets, converting them into solid powders. The liquid feed typically has 10-20% of solids content, and in some cases up to 50% solids or higher. Since there is a lot of energy consumed in heating up the air, higher solids content in the feed could save energy as there is less moisture to be removed. But there are limitations as liquids with higher solids are harder to pump and may also block the nozzle during operation.

Why powders? Ingredients in powder form have the advantage of longer shelf life, ease of storage and transport, and convenience. However, they also need to be rehydrated (usually by adding water) back to their original form and function. For example, milk powder should be able to dissolve quickly in water to resemble fresh milk for consumption. Spray drying conditions are therefore important for the quality of the powder – if the air temperature is too hot, it may damage the powder properties, causing it to be less soluble, which may affect the taste of the product (‘burnt’ taste). The other important factors are the composition and the properties of the liquid feed. A wide variety of foods that exist in liquid or semi- liquid forms (extracts, milk, juice, eggs, etc.) can be spray-dried to convert them into powders.

Next time you browse through the supermarket aisles, pay attention to food items that are sold in powder form, or may contain dry powder ingredients. Most likely they are produced by spray drying!

4. Did you know the pungency of chilli peppers is not a taste?

We all know what it tastes like to bite into a red-hot chilli pepper - be it intentionally or by mistake. The sensation travels across the tongue, burn spreads throughout our mouth and eventually our heads feel hot with some of us breaking into a sweat all over scalp and face. The perception of spiciness which many of us enjoy while eating spicy food, is not at all taste or gustation and rather a manifestation of pain instead. On our tongue we not only have receptors for the classical five taste modalities of sweet, salty, sour, bitter, and umami, we also have receptors for pain and temperature stimulation. Capsaicin, the molecule in red hot chilli peppers, which is responsible for this perception,

5. Did you know that (cow’s) milk allergy and milk intolerance are caused by different biological mechanisms?

Milk is a nutritious food and ingredient with functional properties that are used widely in many food products. But some people cannot drink milk because their body reacts to it. The symptoms they experience vary widely from flatulence or stomach pain to diarrhoea, wheezing, swelling of lips, and hives. Milk intolerance, better known as lactose intolerance, is caused by a lack of an enzyme called lactase in the body to break down lactose to sugars called glucose and galactose. This process of breaking down lactose occurs in the small intestine where lactase is located. Lactose that is not broken down in the small intestine passes through the large intestine and gets similarly utilised by the gut microorganisms through a fermentation process. Gas produced by this process causes flatulence and other symptoms of milk intolerance. The symptoms usually develop 2-3 hours after eating/drinking milk and are NOT life-threatening. Did you know that lactose-free milk is sweeter than whole milk? This is because lactose-free milk is produced by adding more lactase into milk to break down lactose during milk processing, and both glucose and galactose derived from lactose breakdown are sweeter than lactose.

Cow’s milk allergy is caused by the immune system. Our body produces a protein called immunoglobulin, commonly known as an antibody, which is part of the immune mechanism. One of the antibodies called immunoglobulin E (in short IgE) is produced when our body is sensitised to milk proteins. IgE binds to milk proteins causing the release of chemicals such as histamine. Milk allergy or the allergic reaction usually occurs within 15 min of milk consumption and can be life-threatening. People with cow’s milk allergy could also react to milk or dairy products made from goats and sheep. This is because milk proteins from goats and sheep share many similarities with cow’s milk proteins.

Did you know that people with a milk allergy who cannot drink milk can still eat certain foods containing milk such as muffins or cakes and or biscuits? Food processing can change the milk proteins' structure, making them unable to bind to IgE and cannot initiate an allergic reaction.

6. Did you know that fruits are alive?

We all know that one of the main functions of a fruit is to spread seeds and allow the plant to reproduce. Fruits accumulate water and nutrients from the plant, and they use these nutrients to create their flesh and seeds. Fruits are generally hard and unattractive to predators—including us! After seed development and fruit growth, the fruit ripens when it is more attractive. During ripening, there is an increase in the breakdown of starch inside the fruit, and a corresponding increase in the amount of simple sugars, which taste sweet, such as sucrose, glucose, and fructose. Through ripening, fruits become sweet, colourful, and soft. The properties of the fruit. The correct oxygen concentration surrounding fruits during storage is related to the complex mechanisms of gas exchange, respiration, and fermentation in the fruit. Changing the concentration of oxygen, nitrogen and carbon dioxide on the environment surrounding the fruit, and reducing temperature, the rate of respiration is greatly altered bringing the biochemical processes inside fruits into slow motion. How do food scientists and technologists take advantage of this understanding? Firstly, we know that by modifying the composition of the air surrounding fruits during storage, and reducing temperature, fruits are put into “hibernation”, so they can take several months before ripening, and that is why we can enjoy apples every day of the year even if they are out of season. Secondly, by knowing the temperature profile of fruits during transportation and storage, we can predict the precise time of ripening so consumers can enjoy fruits at the onset of ripening.

Hopefully, these examples can give you a snapshot into the exciting world of food science and technology! Interested in finding out more about food science? Consider doing food science at UNSW

Me at work…..year 8

Last week each student in Mr Dowdell’s year 8 group worked on a resume that would help them secure their first job. With their life and work experience limited in most cases, they were guided by a crew of year 10 students on how to express their career goal and dig deep for employability skills they may already possess!