COLOUR FADING IN YOGHURT
Colour fading or shifting in flavoured and coloured yoghurt is a common challenge in the dairy industry. Whether using natural or artificial colourants, several scientifically proven factors contribute to changes in appearance during processing and storage. Understanding these mechanisms is key to maintaining product appeal, consumer confidence, and brand consistency.
Light Exposure
Light - both natural and fluorescent - can degrade colour pigments through photochemical reactions.
• Natural Colours such as anthocyanins, carotenoids, spirulina and beet pigments are particularly sensitive.
• This often leads to fading, dullness, or browning during display or storage.
• Transparent packaging accelerates the problem.
pH Fluctuations
• Yoghurt's acidic environment (usually pH 4.0 - 4.5) influences pigment stability.
• Anthocyanins changes colour dramatically depending on pH and may turn redder, bluer, or brownish.
• pH Shifts from ongoing fermentation or fruit preparation acidity can cause noticeable colour changes.
Temperature Effects
Temperature is one of the most significant contributors to pigment degradation.
• High or Fluctuating storage temperatures break down sensitive colours.
• Even minor deviations
Oxidation
Oxygen exposure - either trapped in packaging or introduced through mixing - cause oxidative reactions.
• This dulls colours, especially in fruit-based pigments and plant-derived extracts.
• Dairy fats can oxidise as well, leading to off-colours and reduced vibrancy.
Interaction with Other Ingredients
Colourants can bind or react with components in yoghurt:
• Proteins may bind pigments, reducing visible intensity.
• Minerals such as calcium can destabilise colours.
• Fruit acids alter pH and pigment behaviour.
• Stabilisers can either protect or negatively influence colour depending on the formulation.
Use of Natural Colours
Natural colourants offer clean-label benefits but are significantly less stable than synthetic alternatives.
• Berry-based anthocyanins, beetroot red, spirulina, turmeric, and vegetable extracts can degrade quickly.
• Their sensitivity to heat, pH, and light contributes to faster fading.
HOW TO IMPROVE COLOUR STABILITY IN YOGHURT
Manufacturers can greatly improve colour retention by applying a combination of formulation strategies, processing control, and packaging optimisation.
Choose More Stable Colourants
• Select colourants specifically designed for acidic dairy systems.
• Prefer heat-stable, light-stable versions where possible.
• Consider encapsulated pigments or emulsion-based colour systems for better protection.
Optimise pH Control
• Stabilise final product pH to reduce pigment shifting.
• Ensure fruit preparations are pre-adjusted to a suitable pH before blending into yoghurt.
Improve Processing Conditions
• Add colourants at the cold stage when possible.
• Minimise heat exposure for sensitive pigments.
• Reduce mixing speeds to avoid unnecessary oxygen incorporation.
Strengthen Packaging Against Light
• Use opaque or UV-protected cups, lids, and films.
• Avoid transparent packaging for colour-sensitive formulations.
Maintain the Cold Chain
• Keep products at consistent refrigeration temperatures throughout production, storage, transportation, and retail display.
• Temperature abuse is one of the fastest ways to accelerate fading.
Manage Oxygen Exposure
• Reduce air incorporation during mixing.
• Consider nitrogen flushing or using low-oxygen packaging systems.
Pair Colours with Suitable Stabiliser Systems
• Some hydrocolloids protect pigments by reducing oxidation or limiting molecular mobility.
• Work with stabilisers that improve viscosity and reduce syneresis, preventing localised pH changes.
CONCLUSION
Colour loss in yoghurt is influenced by light, temperature, pH, oxygen, ingredient interactions, and the natural sensitivity of pigments. By selecting suitable colourants, optimising formulation conditions, and improving packaging and storage controls, manufacturers can significantly enhance colour stability and maintain the premium appearance consumers expect.