Effects of protein enrichment on the microbiological, physicochemical and sensory properties of fermented tiger nut milk

• Tiger nut milk shows pronounced phase separation during fermentation.
• Protein enrichment of tiger nut milk inhibits phase separation in fermented systems.
• Protein enrichment improves textural properties of the fermented system.
• Protein enrichment leads to fermented systems with different sensory properties.

This study aims to explore and improve the quality of fermented tiger nut milk by investigating effects of enrichment with tiger nut proteins or dairy proteins mixed with xanthan gum on the microbiological, physicochemical and sensory properties. Enrichment with tiger nut protein decreased pH of the base system, increased microbial lag time and reduced acidification rate. Dairy proteins marginally increased the viable counts of starter culture and significantly increased acidification rate. Tiger nut milk enriched with tiger nut protein remained liquid after fermentation, whilst dairy protein enrichment caused formation of semi-solid, yogurt-like gels. Fermented gel systems containing sodium caseinate showed higher gel stiffness and lower whey drainage than gels with whey protein enrichment. However, fortification with whey proteins resulted in stirred products of higher viscosity. Frequent sensory descriptors for fermented tiger nut milk were sweet, watery, brown, almond, phase separation, woody and nutty. Fortification with dairy proteins resulted in sensory attributes that may be pivotal for improving the properties of fermented tiger nut milk.