Over the past decade, there has been an unprecedented increase in consumer awareness of gut-induced immunity and digestive health, leading to great interest in prebiotics and ingredients that influence gut microflora. The number of new product introductions with prebiotics has steeply increased over the last four years. While probiotics are predominantly used in fermented dairy products, the use of prebiotics has expanded into other food categories. For instance, the introduction of galacto-oligosaccharides (GOS) into baby foods has been very successful.
Prebiotics are defined as non-digestible food ingredients that beneficially affect the host's health by selective stimulation of growth of one or a limited number of species of bacteria in the colon. Vivinal GOS, from FrieslandCampina Domo, is derived from lactose, and consists of a galactose polymer with a glucose end unit. GOS are naturally present in mother's milk. Clinical studies show that Vivinal GOS has several health benefits, including improvement in digestive health, immune support and improved mineral absorption.
This article, however, focuses on the ingredient's sensory and formulation aspects.
Vivinal GOS is a versatile, functional ingredient, suitable for a broad range of food and beverage applications. It is sold as a syrup, with a high dry matter content (75 per cent) or as a powder. It is instantly dispersible and clear in solution, and so can be easily handled in various food and beverage systems. It has a neutral, slightly sweet taste profile, with low caloric density (2kcal/g). This makes it very easy to add to formulations.
It is heat and acid stable, during both processing and storage. Some other prebiotics, such as fructo-oligosaccharide s(FOS), become hydrolysed under similar conditions. Stability studies show that Vivinal GOS is not hydrolysed by heat or low pH, even when stored for up to six months at ambient conditions (See Figure 1). This ensures that adequate and effective amounts of the ingredient are retained in the product during the full shelf life. There is no need to increase initial dosages to compensate for functionality losses during shelf life, resulting in an optimal cost in use.
Figure 1. Stability of GOS vs FOS in soft drink model, pH 3, ambient storage
Any addition of ingredients will have an impact on sensory properties of a product. That goes for prebiotics as well, especially as they act as both sweetener and texturiser. This sometimes causes grittiness or chalkiness, negatively affecting sensory quality. Sensory evaluation trials with plain yoghurt comparing Vivinal GOS, scFOS and lcFOS (inulin) showed significant differences in their sensory effects. GOS enhanced sweetness and improved the creamy taste of the yoghurt, to a much greater extent than inulin or FOS, without negative side effects such as roughness or filming (See Figure 2).
Figure 2: Sensory profiling of prebiotics in plain yoghurt. GOS enhances sweetness and creaminess.
These results clearly show that Vivinal GOS is a viable prebiotic for yoghurt and dairy applications. It is stable during processing and shelf life, and enhances sensory profiles. It can be added in all stages of production, as the syrup blends in very easily. In fruit yoghurts, for instance, it can be added to the fruit base, enabling more flexibility in the yogurt production process.
The positive flavour effect of this GOS is not only limited to dairy. In orange juices, it enhances fresh orange-peel flavours and reduces oxidation markers. This in turn boosts the overall fruit flavour. Other prebiotics show opposite effects.
Reduced sugar formulations
Vivinal GOS has up to one-third the sweetness of sucrose, while at 2kcal per gram, it has only half the calories. It can therefore be successfully used in reduced-sugar formulations, particularly without the thin mouthfeel often encountered in reduced-sugar products.
In a reduced-sugar juice drink, 5g GOS syrup can be used as a partial replacement for high-fructose corn syrup. This provides a caloric reduction of 10kcal per serving, while the amount of GOS used (for 2.5g GOS/240ml serving) is sufficient for the prebiotic claim. The replacement of sugar and high-fructose corn syrup also avoids negative associations on the product label.
Reduced-fat yoghurt was also formulated with five per cent GOS as a partial replacement for high-fructose corn syrup. This resulted in a caloric reduction of 14kcal per serving.
Emerging evidence shows that consuming GOS increases levels of satiety hormone PYY compared to a control meal with similar energy value. This study, conducted in rats, indicates a satiety mechanism, induced by the specific short chain fatty acids formed after fermentation of GOS in the colon. Hence, the ingredient has the potential to induce satiety and support weight management — not only by reducing energy intake by suppressing hunger but also via reducing sugar and fat levels due to its low caloric value and excellent sensory properties.
This research is still ongoing and more results are expected to substantiate the relation with satiety. It also shows the unprecedented possibilities of GOS as an ingredient combining excellent functional and sensory properties with clear and well-substantiated health benefits.
Hans Zijlstra is manager of R&D application development for FrieslandCampina Domo, which develops, produces and markets a broad range of high-quality, distinctive ingredients and semi—finished products based on whey, milk and other dairy components. Vivinal brand GOS is a prebiotic galacto-oligosaccharide developed, produced and marketed by FrieslandCampina Domo.