Fruit juice: healthy beverage choice, or health halo effect?

For decades, fruit juice consumption has been associated with a healthy lifestyle, based on the belief that these products are a good source of vitamins and contain healthy sugars. But do the products we purchase offer the nutritional value that we perceive them to? Research has shown that consumers may form nutritional inferences about a specific product, leading to an overestimation of its healthiness – known as the health halo effect. Could this be the case with fruit juice?

Commercially-produced fruit juice is typically made from hydrated juice concentrates. After extraction, fruit juice is filtered, clarified, and then concentrated – via evaporators, reverse osmosis or freeze concentration – before final pasteurisation. The concentration step removes as much water as possible from the product, which helps to reduce bacterial growth and spoilage, extends product shelf life, and lowers the cost of packaging, storage and transportation. During the final stage of production, the concentrates are reconstituted with water and packaged for sale.

During these processing steps, micronutrients naturally present in fruit juice are often lost. To compensate for these losses, producers may enrich juice products with selected vitamins. But to what extent? As an example, eight popular orange juice brands (100% fruit juice blend) were selected from local supermarkets, and their vitamin C content and price per litre were compared (Table 1).

Table 1. Vitamin C content^$ and price of eight commercial orange juices (100% fruit juice blend).

As shown in Table 1, the vitamin C content differs significantly between brands. According to the popular nutrition-analysis software Nutritics, freshly squeezed orange juice contains 48mg of vitamin C per 100ml of juice. Besides product 4 (75.0mg/100ml), the vitamin C content of all the other orange juice brands was lower than that of unprocessed, freshly squeezed orange juice. Products 3 and 5 may have a vitamin C level below the required 5% Nutrient Reference Value (NRV) per serving, perhaps explaining why their vitamin C figures are absent from the nutrition labels of these brands; these products may not have been enriched with vitamin C. Interestingly, these two orange juice brands also fetch a lower price than the other juice brands, which could be linked to the cost of enrichment.

Besides vitamin content, it is important to realise that fruit juice doesn’t always offer the same nutritional value as fresh, whole fruit. Fruit juice offers less fibre per serving than whole fruit, and often contains as much sugar as many classic sugar-sweetened beverages. The sugar content of orange and apple juice products from the same eight fruit juice brands in Table 1 was compared to that of sugar-sweetened beverages, which generally contain around 11g per 100ml of beverage. On average, orange juice was found to contain 10.3g total sugar per 100ml, and apple juice 10.2g total sugar per 100ml. Grape juice, however, was found to contain more total sugar per 100ml than sugar-sweetened beverages, with an average of 13.0g from four local fruit juice brands.

But what about the types of sugars found in fruit juice? Fruit generally contains a mixture of fructose and glucose, with relevant proportions dependent on factors such as cultivar, climatic conditions during ripening, and conditions of storage and preservation. Compared to glucose, the consumption of fructose has a reducing effect on blood sugar levels as it is completely metabolised in the liver, giving it the connotation of a ‘healthy’ sugar. According to the regulations relating to the classification, packing and marking of fruit juice and drink intended for sale in the Republic of South Africa (R286), 100% fruit juice blends should not contain any “added” sugar; therefore, the sugar content in these juices should resemble that of the fruits from which they are derived. Thus, even though a glass of fruit juice and a glass of sugar-sweetened beverage have a similar sugar content, the way in which the body processes these sugars will differ, with fruit juice being the better option.

Another factor that may influence the nutritional value of fruit juice is the addition of deflavoured juice concentrates. Deflavoured juice concentrates are typically of apple or pear origin, and undergo processing through which volatile and non-volatile natural flavour compounds are intentionally removed. This process creates a sweet, syrupy product that is used to bulk out juices of more expensive fruit varieties, such as litchi, mango, grape, etc. According to R286, deflavoured fruit juices are classed interchangeably with 100% fruit juice blends, provided that the juice blend retains the characteristic appearance, flavour and taste of the labelled ingredient and that the labelled ingredient makes up not less than 6% (v/v) juice in the blend. However, beyond their flavouring properties, volatile and non-volatile compounds have been shown to play a role in human health, contributing antioxidant, anti-inflammatory, anti-cancer and anti-obesity effects. Thus, their removal in the production of deflavoured juice concentrates may influence the nutritional value of the fruit juice end product.

Considering all these factors, commercially-available fruit juice products may not offer the nutritional value that consumers expect. Product purchases may be driven more by the health halo effect than actual scientific evidence. When comparing the nutritional value of a commercial fruit juice product to that of a freshly pressed fruit juice, the commercial product may well be found lacking. Even so, fruit juice may still be the healthier beverage choice compared to other soft-drink alternatives available on our local shelves, based on sugar profile and vitamin content.

Beyond typical processing, it is also important to consider the risk of fruit juice adulteration. Sugar syrups can easily be substituted into 100% fruit juice concentrates, rendering them non-compliant with regulations, as well as altering the nutritional profile of the product. High-resolution mass spectrometry profiling is a useful analytical technique to screen for the presence of adulterants in fruit juices, by comparing sugar profiles and detecting marker compounds.

This study was featured in Times live, view the article here.

If you suspect fruit juice fraud or are interested in investigating the sugar profile of a fruit juice, contact us for more information.