In response to high consumer demand, the food industry is increasingly focused on developing plant-based beverages (PBMA) that mimic the desirable sensory properties of animal-based beverages. While extensive research has characterized the differences in appearance, aroma, taste, and flavor between PBMAs and cow’s milk, limited research exists that comprehensively characterizes the textural and mouthfeel differences between these two types of beverages. Moreover, the complexity of texture and mouthfeel perception poses a challenge in formulating these beverages. Formulation changes that have minimal impact on analytical measurements can still result in significant perceptual differences in texture and mouthfeel sensations. Finally, there has been little research exploring the mechanical underpinnings of textural and mouthfeel perception of food within oral cavity. To address these gaps, this dissertation aimed to comprehensively characterize textural and mouthfeel differences between PBMAs and cow’s milk and relate these sensations back to oral tactile sensitivity.
Utilizing a “top-down” approach, trained panelists were used to develop a comprehensive texture and mouthfeel lexicon to characterize sensory differences between animal and plant-based beverages. Sixteen unique texture and mouthfeel attributes were identified and used by trained panelists to evaluate 14 different liquid beverages, categorized by protein content: low protein (LP; 8g of protein/8fl. oz) and high protein (HP; 13g of protein/8fl. oz). Each beverage group included two types of animal-based beverages (commercial skim milk [CSM] and milk protein isolate [MPI]) and five types of plant-based beverages (pea protein isolate [PPI], soy protein concentrate [SPC] and three types of soy protein isolates [SPI 1-3]). Textural and mouthfeel similarities were evident between LP animal-based beverages, while only nuanced differences were observed within the LP-SPIs. In contrast, LP-SPC was significantly different in 8 out of the 16 attributes compared to other LP beverages. Similarly, HP animal-based beverages exhibited comparable textural and mouthfeel characteristics, with small differences observed within the HP-SPIs. HP-SPC significantly differed in 9 out of the 16 attributes compared to other HP beverages. Overall, the trends observed among the different protein in LP beverages were reflected in HP beverages. These findings emphasize that textural and mouthfeel differences between plant and animal-based beverages are mainly driven by the type of protein used, rather than by protein concentration.
A “bottom-up” approach was then used to explore the relationship between oral tactile sensitivity and texture perception (Chapter 4). Thirty-four panelists assessed the astringency, mouth coating, and smoothness of LP-SPC and LP-CSM, along with suprathreshold oral tactile sensitivity to lingual/rugal roughness, lingual punctate pressure, thickness, and grittiness. Significantly correlations were observed between rugal roughness sensitivity and perceived astringency (r=0.45, p=0.001), tongue roughness sensitivity and perceived mouth coating (r=0.38, p=0.02), stimulus thickness sensitivity and perceived mouth coating (r=0.44, p=0.01), and stimuli grittiness sensitivity and perceived smoothness (r=-0.38, p=0.03). These findings suggest that suprathreshold mechanosensitivity of oral tissues contributes to the perception of astringency, mouth coating, and smoothness in beverages, emphasizing the importance of considering multiple oral surfaces and tactile stimuli in texture and mouthfeel research.
Lastly, Chapter 5 built upon the findings in Chapter 4 by delving deeper into the mechanisms underpinning astringency perception in the human oral cavity. Chapter 5 investigated the role of transient receptor potential (TRP) channels in astringency perception within the oral cavity. Thirty-seven panelists underwent unilateral lingual desensitisation of TRPA1 and TRPV1 channels using mustard oil and capsaicin, respectively. Subsequently, panelists evaluated four astringent stimuli: epicatechin (EC), epigallocatechin gallate (EGCG), potassium alum (Alum), and tannic acid (TA) using 2-AFC and intensity ratings. When TRPA1 receptors were desensitized via mustard oil, no significant differences were observed between the treated and untreated sides for both 2-AFC and intensity ratings. Similarly, when TRPV1 receptors were desensitized via capsaicin, no significant differences were observed between the treated and untreated sides for both 2-AFC (except TA) and intensity ratings. These findings challenge previous suggestions that TRP channels playing a pivotal role in astringency perception in the human oral cavity.
In summary, this dissertation addresses the critical gap in understanding the textural and mouthfeel differences between plant and animal-based beverages. By utilizing both “top-down” and “bottom-up” approaches, we provide a comprehensive understanding behind sensory differences between these beverages. Overall, these findings provide valuable insight to guide the development of the next generation of PBMAs as suitable alternatives to cow’s milk.