Written by Emily Burch, Accredited Practising Dietitian and PhD candidate with Griffith University’s Healthy Primary Care team. Through her current research, Emily is working with Diabetes Australia towards improving the management of people newly diagnosed with type 2 diabetes in Australia. Emily is investigating how diet quality changes over time after diagnosis with type 2 diabetes and the factors that influence these changes.
We all know that fruits and vegetables are great for our bodies and are among the healthiest foods available for us to eat. This is because eating lots of fruits and vegetables protects us against a variety of diseases like diabetes, cancer and heart disease. Unfortunately, most people do not have home gardens capable of supplying fresh produce year-round. But is fresh produce always better than frozen produce? Not necessarily!
There are a couple of things to consider here – let’s explore them in more detail.
Harvesting methods and food mileage
In Australia, fruits and vegetables often have to travel very long distances to get from where they were grown onto our plates (sometimes taking several days). This can cause oxidization and degradation of their nutrients. Fresh fruit and vegetables from major supermarkets are also frequently picked before they are ripe, with transportation allowing them time to ripen. This means the produce has less time to develop its full range of nutrients in the soil.
On the other hand, frozen fruits and vegetables are usually picked at peak ripeness and snap frozen soon afterwards, maintaining maximum nutrient levels. However, the vegetables undergo “blanching” which takes place prior to freezing and is when the produce is boiled in water for a short period of time.
Blanching is an important preservation step in the freezing process of many vegetables. Fruits, on the other hand, are usually not blanched prior to freezing owing to their delicate nature and inherent acidity. Certain nutrients are lost in the blanching process.
Nutrient decline during storage
It will come as no surprise that those soggy carrots at the back of your fridge aren’t quite as nutrient dense as they were when you first picked them up fresh from your grocery store!
Certain nutrients in fresh food decline significantly during storage. For example, one study found green peas lose just over half their vitamin C content in the first 24-48 hours after picking. But there is more to fruit and vegetables than just their vitamin content. Dietary fibre is a very important component. The great news is fibre content doesn’t depreciate easily, which means week-old fresh produce still has value!
Lower temperatures in frozen produce, tend to prolong the shelf life of fruits and vegetables. In general, evidence suggests that freezing can preserve nutrient value, and that the nutritional content of fresh and frozen produce is similar.
There are ‘pros’ of both fresh and frozen!
The pros of fresh produce are that it often tastes much better, is easier to eat than frozen produce (e.g. reaching for an apple is handier than making a meal with frozen fruit) and often has a better texture.
The pros of frozen produce are that nutrients are “frozen in” soon after picking, they are often more convenient as you can store them for months on end and they give us opportunity to eat vegetables and fruit that might be out of season (e.g. mangoes in winter and pumpkin in summer).
So which is better?
The key takeaway message from all this is that certain nutrients in fresh fruit and vegetables begin to decline immediately after harvesting.
Obviously, the best outcome would be for you to grown your own and eat that, but this is not realistic for most people. Instead focus on buying locally from farmers in the area (or close enough), buy seasonally, don’t store produce for excessive periods of time and don’t be afraid of buying frozen fruit and vegetables too. At the end of the day, the only ‘wrong’ way to consumes vegetables is to not consume them enough!
If like Emily you’re interested in understanding how the food we eat affects our lives and our environment, a degree in nutrition and dietetics might be for you. If you’re interested in furthering your career with research, find out more about Griffith’s Higher Degree by Research.