Texture and mechanical properties of prok backfat

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Abstract
Summary: A puncture test for measuring the firmness of backfat is described for use in studies of the effects of changes in animal production, and meat processing on the quality of fatty tissue. The operating and recording conditions were chosen from sensory deformation characteristics used in firmness evaluation when pressing fat with the index finger. On average, assessors exerted aaaximum force of about 30 N and caused a deformation of 4 mm in 2 sec and the best predictor of firmness was the maximum deformation they applied. Mechanical properties of the fats were determined by stress relaxation and the modulus 2.5 sec after compression was about 80 × 104 for hard and < 3 × 104 N/m2 for soft fat at 3°C and the logarithm of the modulus was linearly related to the subjective firmness rating.In the puncture test, the forces required to drive a stainless steel punch (3.5 mm in diameter) 2.5 or 4.0 mm into backfat at 3°C at 2 mm/sec correlated well (r > 0.8) with firmness rating and five replicate determinations using the punch proved more discriminating than a panel of four assessors. A combination of the forces required on inner and outer layers of fat accounted for 93% of variation in firmness assessments.