Evaluation of konjac gels as fat substitutes in meat "emulsion" products

Abstract

Two konjac types (Konjac/Starch, KS, Nutricol[] GP 440; Konjac/Carrageenan, KC, Nutricol[] GP 624) were incorporated into low-fat (3%) bologna formulations at two levels (10 and 20%). Each treatment combination was manufactured using a 65 and 70% meat block (65MB and 70MB, respectively), and compared to 3 or 30% fat controls formulated from the same meat base. Comparisons of konjac 65MB treatments were made only with the 3% fat control (3C) due to "fatting out" of the 30% fat control (30C) during heat processing. All konjac treatments were formulated to contain 3% fat to meet USDA nutritional labeling requirements for low-fat bologna and to be comparable to other low-fat products currently available at the retail level. Protein and fat contents, expressed water, bound water, water activity (aw), and cook yield were not different among 65MB treatments. Percent moisture was slightly higher in KC20 (65MB) in comparison to 3C and KS20, and pH was lower in 3C (6.02) and higher in KS20 (6.15). No differences were observed in true shear stress, true shear strain, and texture profile analysis (TPA) parameters among 65MB treatments. However, rigidity or stiffness (shear modulus, G) and sensory panel fracturability were less for KC20 than all other treatments. In general, low-fat 70 MB samples (3C and konjac treatments) as evaluated by torsion test, TPA, and sensory panel were harder, more rigid, springier, more cohesive and harder to fracture than 30C. For most textural traits, KS and KC were similar, but KC tended to be slightly softer, less springy, less hard and more easily deformed than 3C. Bologna containing either KS or KC was similar to 3C for most traits evaluated, but quite different compositionally, texturally and color-wise from 30C. Based on torsion analysis, 30C was texturally similar to commercial beef bologna while konjac treatments were more similar to low-fat turkey bologna manufactured with mechanically deboned turkey meat. Fat replacements derived from the konjac/starch or konjac/carrageenan gels tested contributed positively to low-fat bologna formulations and could serve as fat mimics to reduce the caloric density of processed meat products.