Chemical, rheological, microbial and sensorial properties of bio-Greek yogurt made from cow, buffalo, goat, sheep or camel milk using transglutaminase
This study demonstrates that bio-Greek yogurt produced from sheep, buffalo, and cow milk using transglutaminase and probiotic cultures exhibits superior chemical, rheological, and sensory properties compared to those made from goat or camel milk, although the latter offer distinct advantages in antioxidant activity and specific probiotic viability.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Yogurt is a familiar comfort, a thick, tangy spoonful of fermented milk that has nourished people for centuries. But not all yogurts are created equal. The texture, flavor, and nutritional punch of a cup of yogurt depend heavily on the animal that provided the milk. A cow's milk yogurt behaves differently from one made with goat, sheep, buffalo, or even camel milk, because each animal's milk carries a unique chemical fingerprint of proteins, fats, and sugars. In recent years, a specific style known as Greek yogurt has surged in popularity, prized for its dense, creamy consistency and high protein content. Traditionally, this thickness is achieved by straining out the watery whey, but modern producers often look for other ways to boost the protein and firmness without losing the smooth mouthfeel. One tool in this process is an enzyme called transglutaminase, a natural protein binder that helps milk molecules stick together more tightly, creating a stronger gel. Another trend is the addition of probiotics, live beneficial bacteria that support gut health. The question facing food scientists is whether these techniques can work equally well across the diverse world of animal milks, or if some milks simply resist the transformation into a high-quality Greek yogurt.
A team of researchers set out to answer this by creating a series of bio-Greek yogurts using five different milk sources: cow, buffalo, goat, sheep, and camel. They did not just mix the milk and wait; they engineered the process to ensure a consistent, high-protein product. To every batch, they added 8% milk protein concentrate (MPC) to boost the solid content, a standard practice for making Greek-style yogurt. They then introduced the enzyme transglutaminase to strengthen the protein network, followed by a blend of probiotic cultures, including bacteria known for aiding digestion. The goal was to see how each milk type responded to this treatment and to measure the final product's chemical makeup, texture, and taste. They stored the yogurts in refrigeration for two weeks, checking them at the start, at one week, and at the end to see how they held up over time.
The results revealed a clear split in performance based on the animal source. The yogurts made from sheep and buffalo milk emerged as the top performers in almost every category. Because these milks naturally contain high levels of fat and protein, the resulting yogurts were the thickest and most stable. They held onto their water the best, meaning they did not leak a watery layer of whey on the surface, a common defect in thinner yogurts. When the researchers pressed on the samples to measure their firmness, the sheep and buffalo versions were the hardest and most chewy, qualities that consumers often associate with a premium, creamy texture. In sensory tests, where trained tasters and regular customers judged the products, these two milks won the highest scores for their bright white color, smooth body, and pleasant flavor. The cow milk yogurt also performed well, sitting comfortably in the middle of the pack, while the goat milk yogurt struggled with a softer texture and a distinct flavor that some panelists found less appealing.
The camel milk yogurt presented a different story. While it did not achieve the same creamy thickness or firm texture as the sheep or buffalo versions, it shone in other areas. The researchers found that the camel milk yogurt was the most potent source of antioxidants, compounds that help protect the body from damage, and it contained the highest levels of total phenolic content, a measure of these beneficial plant-like chemicals often found in food. Furthermore, the camel milk provided the most hospitable environment for the probiotic bacteria. The beneficial bacteria known as Bifidobacterium bifidum thrived in the camel milk yogurt more than in any other type, reaching higher population counts. This suggests that while camel milk might need extra help to achieve the perfect Greek yogurt texture, it offers a unique nutritional profile that other milks cannot match.
Throughout the two-week storage period, the researchers watched how the yogurts changed. The probiotic bacteria in all the samples remained alive and active, staying well above the minimum level required to be considered a probiotic food. However, the texture of the yogurts did shift over time. The samples generally became firmer and chewier as they aged, while their ability to spring back to shape slightly decreased. The enzyme added at the beginning played a crucial role here; by cross-linking the proteins, it helped all the yogurts maintain a better structure than they would have had without it. The study confirmed that while sheep and buffalo milk are the ideal candidates for producing a thick, creamy, and sensorially pleasing Greek yogurt, camel milk offers a distinct health advantage that could be valuable if its texture issues are solved. The researchers noted that future work could focus on blending camel milk with other types or adding natural ingredients like honey or fruit to improve its body and flavor, potentially unlocking its full potential as a functional food.
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