Chemical, physical and sensory changes of small abalone meat during cooking

ABSTRACT:   Small abalone meats were heated at 80°C and 98°C for 0–120 min and the differences in chemical, physical and sensory changes of the cooked meats were investigated. The decrease in moisture and weight and the increase in browning and Hunter's b -value were relatively higher for cooking at 98°C than at 80°C. After cooking for 20–120 min, the total amount of adenosine triphosphate and its related compounds on a dry weight basis decreased by 17–27% at 80°C and by 30–39% at 98°C; the total amount of free amino acids on a dry weight basis changed insignificantly at 80°C but decreased by 22–35% after cooking at 98°C. The meats cooked at 80°C were higher in cutting force whereas the levels in the samples cooked at 98°C did not decrease until samples had been cooked for 60 min. The hydroxyproline content showed little change during cooking except for in samples cooked at 98°C for 120 min, in which the content was found to be low. The extended cooking at 80°C improved the acceptability of small abalone meat, whereas only the acceptability score of aroma increased significantly for cooking at 98°C.     

Depletion of ascorbic acid derivatives in fish feed by the production process

ABSTRACT:   The depletion of ascorbic acid derivatives in fish feed during the feed processing (extrusion cooking and drying) was studied at five extrusion cooking temperatures and at 85°C for 2 h dryer processing temperature. Three ascorbic acid derivatives were used: L-ascorbyl-2-mono-phosphate Mg (APM), L-ascorbic acid sodium (AAS) and L-ascorbic acid palmitic acid ester (AAP). Samples were collected after drying and ascorbic acid derivatives losses evaluated. APM was found to be quiet stable with an average retention of 88%, but AAS and AAP were unstable and the depletion was very high.     

Effects of extrusion cooking on some functional properties of soy-sweet potato mixtures – A response surface analysis

Mixtures of defatted soy flour and sweet potatoes wereextruded at 0:100, 25:75, 50:50, 75:25 and 100:0ratios in an Insta-Pro 600 single screw extruderoperated at 180, 200, 220 rpm.Oil (3–5%) was added into the mix before extrusion.A 5×3² fractional factorial central compositeresponse surface design was adopted forinvestigating the variables: feed composition, % oil,and screw rotation speed (RPM). Percent oil andscrew speed were randomly investigated at threelevels, while feed composition was randomlyinvestigated at five levels. Effect of extrusioncooking on functional properties: bulk density,expansion ratio, water absorption and solubilityindices and trypsin inhibitor were assessed.Results showed that feed composition and screw speedhad strong influences on the process. The effect ofadding oil, into defatted soybean significantly(p<0.05) affected only trypsin inhibitor content.High extrusion temperature (>130 ^°C), andaccompanying high shear, were the result of thenon-pasting nature of the extrudate. Therefore theproducts may have limited uses.