ARS | Publication request: Relating instrumental texture, determined relating instrumental texture, determined attachments, to sensory analysis of rainbow trout, Oncorhynchus mykiss, fillets

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 20, 2010
Publication Date: September 22, 2010
Citation: Aussanasuwannakul, A., Kenney, P., Brannan, R.G., Slider, S.D., Salem, M., Yao, J. 2010. Relating instrumental texture, determined relating instrumental texture, determined attachments, to sensory analysis of rainbow trout, Oncorhynchus mykiss, fillets. Journal of Food Science. 75:S365-S374. DOI: 10.1111/j. 1750-3841.2010.01770.x.

Interpretive Summary: Texture is an important quality attribute of aquatic foods that have delicate muscle structures. Texture defects such as muscle softening and gaping are caused by ante- and postmortem handling. The mechanism underlying these problems relates to compositional changes and protein denaturation. Our goal was to validate through sensory analysis a novel, variable-blade (VB) shear for use with aquatic foods, and to compare this device with the widely used AK attachment. Different refrigeration/frozen storage time combinations and cooking were used to generate a range of fillet textures. Instrumental measurements were compared with sensory measurements to determine the attachment's accuracy in assessing cooked fillet texture. The VB attachment could measure the effects of shear direction on fillet texture and predict the key texture attribute (hardness). The VB attachment was determined to be an accurate, valid, and less destructive instrument for fillet texture analysis.

Technical Abstract: Texture is one of the most important quality attributes of fish fillets, and accurate assessment of variation in this attribute, as affected by storage and handling, is critical in providing consistent quality product. Trout fillets received 4 treatments: 3-d refrigeration (R3), 7-d refrigeration (R7), 3-d refrigeration followed by 30-d frozen storage (R3F30), and 7-d refrigeration followed by 30-d frozen storage (R7F30). Instrumental texture of raw and cooked fillets was determined by 3 approaches: 5-blade Allo-Kramer (AK) and variable-blade (VB) attachment with 12 blades arranged in perpendicular (PER) and parallel (PAR) orientations to muscle fibers. Correlation between instrumental texture and sensory hardness, juiciness, elasticity, fatness, and coarseness was determined. Muscle pH remained constant at 6.54 to 6.64. Raw fillets lost 3.66% of their original weight after 30-d frozen storage. After cooking, weight loss further increased to 15.97%. Moisture content decreased from 69.11 to 65.02%, while fat content remained constant at 10.41%. VBPER detected differences in muscle sample strength (P = 0.0019) and demonstrated effect of shear direction reported as maximum force (g force/ g sample). AKPER detected differences in energy of shear (g × mm; P = 0.0001). Fillets that received F30 treatments were less extensible. Cooking increased muscle strength and toughness. Force determined by VBPER was correlated with sensory hardness (r = 0.423, P = 0.0394) and cook loss (r = 0.412, P = 0.0450). VB attachment is accurate, valid, and less destructive in fillet texture analysis.