Small Oscillatory Rheology: Evaluating Microstructure and Component Interactions in Different Food Systems

Food has been categorized as solid, molecular dispersion, colloidal (e.g., emulsions, gels, sols), and coarse dispersion that exhibit unique rheological behavior driven by polysaccharides, proteins, and lipids. These compounds exhibit various functional attributes such as texture, stability, and sensory quality. During processing, starch gelatinize, proteins denature and coagulate, and fat droplets interact with biopolymers to form viscoelastic or structured networks. These molecular and microstructural changes directly influence rheological behavior. Small-amplitude oscillatory shear (SAOS) rheology has been used as an effective tool in analyzing the microstructure and component interactions within diverse food systems. By probing linear viscoelastic properties under small deformations, SAOS enabled the characterization of structural transitions without disrupting the internal structure. Additionally, variations in viscoelasticity, viscosity, and friction control microstructural breakdown, bolus cohesion, and swallowing, thereby linking rheological responses across oral time scales with sensory perception. These measurements provided insights into the viscoelastic balance of storage and loss moduli, which reflected molecular interactions, network formation, and stability of food matrices. Additionally, the present study explored the application of SAOS that characterizes the viscoelastic behavior of food, which closely linked to their microstructure and component interactions. This review discussed how microstructure influences food rheology, particularly under SAOS conditions, and explored the integration of computational fluid dynamics (CFD), mathematical modeling, and advanced microstructure analysis techniques (e.g., microscopy) to enhance our understanding of food systems. Practical Application: SAOS plays a significant role in dairy, bakery, and starch industries. It provides valuable insight into structure-function relationship of food linking viscoelastic properties with microstructure and molecular interaction. It enables dairy technologist in understanding and optimizing the texture, gel formation, and stability in products like yogurts and cheese, ensuring proper gel structure, preventing syneresis, and achieving consumer-preferred textures. For the bakery industry, rheological insights into dough properties are essential for controlling gluten development, starch gelatinization, and protein coagulation, which directly impact the crumb structure, texture, and rise of bread and cakes. Additionally, it aids in formulating gluten-free and reduced-fat baked goods by identifying suitable substitutes to replicate desired viscoelastic properties. In the starch industry, dynamic rheology is crucial for assessing gelatinization/retrogradation behavior and stability of native and modified starches, optimizing their use in applications like thickened sauces, weaning food, and confectionery. It also facilitates processing optimization during heating, cooling, and extrusion, ensuring consistent product quality. Additionally, rheological study provides a powerful framework for designing foods that perform reliably during oral processing in the presence of saliva. This approach is particularly valuable for developing texture-modified and dysphagia-oriented foods that retain consumer-acceptable mouthfeel while ensuring safe swallowing, thereby supporting healthy aging and improving quality of life.