The effect of extrusion conditions on mechanical-sound and sensory evaluation of rye expanded snack

• Published in: Journal of food engineering 2012-06, Vol.110 (4), p.532-540
• Main Authors: Saeleaw, Mayyawadee, Dürrschmid, Klaus, Schleining, Gerhard
• Format: Article
• Language: English
• Subjects: Acoustic; barrels; Barrels (extruders); Biological and medical sciences; cell walls; Cereal and baking product industries; Cooking; Correlation; Extrusion; Extrusion cooking; Food engineering; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; hardness; Heating; Moisture content; quantitative analysis; rye; Rye extrudate; Rye flour; sensory evaluation; sensory properties; snacks; Sound; Sound emission; temperature; Texture; water content
• ISSN: 0260-8774; 1873-5770
• DOI: 10.1016/j.jfoodeng.2012.01.002

► A predictive model was established for textural and acoustic properties of rye-based extrudates. ► The model showed significant interactions between barrel temperature and feed moisture. ► Relationships between sensory attributes and instrumental data could be demonstrated. Rye-based extrudates were produced according to different conditions of barrel temperature (150°C and 190°C) and feed moisture content (12% and 16%) using a 22 factorial design. A combined mechanical and acoustic method was employed using a texture analyzer (TA-XT Plus, Stable Micro Systems) in combination with the acoustic envelope detector (AED), to describe the influence of extrusion parameters on the properties of extrudates. The results showed with increasing extrusion cooking temperature increasing number of force and number of sound peaks but decreasing maximum forces. Moreover the thickness of the cell wall decreased with increasing extrusion cooking temperature. All these trends were reversed with increasing feed moisture content. The results show further significant interactions, which means that the effect of barrel temperature depends on the feed moisture content and vice versa. Additionally, the quantitative descriptive analysis (QDA) was applied to examine the products in terms of sensory properties. The data were analyzed by principle component analysis (PCA) in order to investigate the relationship between sensory attributes and the instrumental data. The PCA showed a positive correlation between the sensory parameters hardness and sound intensity of crunchiness and the instrumental parameters force area, mean force, maximum force, and negative correlations between the number of sound peaks, mean sound peak, number of force peaks and crunchiness.