Henryk Daun

Changes in texture, cooking losses, and myofibrillar structure of bovine M. semitendinosus during heating.

Vacuum-packed slices of bovine semitendinosus (ST) muscle were retorted to internal temperatures of 50, 60, 70, 80, 90, 100, and 121°C. Changes in texture of the meat were evaluated by measurements of Texture Profile Analysis (TPA) parameters. Changes in microstructure were evaluated using a Scanning Electron Microscope (SEM) and measuring fibre diameter and sarcomere length. Cooking losses were also estimated. During heating the TPA parameters changed independently of each other. They reached a maxima at different endpoint temperatures of the meat and then decreased. A decrease in fibre diameter was observed in samples heated to 60 and 121°C. Sarcomere length decreased continuously in the range 50-121°C. Cooking losses increased with increased heating temperature. Relationships between changes in sarcomere length and cooking losses and between springiness and fibre diameter were found.

Influence of PROP taster status and maternal variables on energy intake and body weight of pre-adolescents

Genetic taste blindness to the bitterness of 6-n-propylthiouracil (PROP) may be a marker for increased energy intake and body weight. This hypothesis has not been tested in pre-adolescent children. This study determined if non-taster children would report higher energy intakes and maintain higher body weights than taster children. Maternal variables which are known to influence food intake and body weight during childhood were also considered including maternal weight, maternal restraint and disinhibition and child feeding practices. Sixty-five children with a mean age of 9.0+/-0.2 years participated. They completed a 3-day diet recall for the estimation of daily energy and macronutrient intakes. BMI (mothers) and BMI%-for-age (children) were calculated from measured heights and weights. Non-taster children reported higher daily energy intakes than super-taster children (p < or = 0.05), but no differences in macronutrient selection were observed. Also, children of disinhibited mothers reported higher daily energy intakes than children of mothers who were not disinhibited (p < or = 0.05). However, these variables did not predict childrens body weight. Rather, regression modeling (R2 = 0.59; p < or = 0.0001) revealed that restriction, concern for child weight and maternal BMI were positive predictors of childrens BMI%-for-age and pressure to eat was a strong negative predictor (p-value range = 0.02-0.004). PROP status was not a predictor of body weight in these children. These results suggest that in pre-adolescent children, current energy intakes were negatively related to childrens PROP status and positively related to maternal disinhibition. However, BMI%-for-age, a measure of long-term energy balance, was related to child feeding practices and maternal BMI.

Characterization ofβ-carotene thermal degradation products in a model food system

A model system developed in our laboratory for the study of thermal degradation products (TDP) of carotenoids was employed.β-Carotene (10 g) in glycerol was heated at 210 C for 4 hr, 1 hr, 15 min and 5 min. The time and temperature chosen were similar to edible oil deodorization and deep fat frying. In this study, the TDP ofβ-carotene were quantified as influenced by time and temperature of heating. Results indicate that at 210 C, degradation is almost complete after 4 hr and most of the nonvolatile products are viscous, yellow-brownish material. Shorter times (1 hr, 15 min and 5 min) cause less degradation. TDP include nonpolar as well as oxidized derivatives ofβ-carotene. The results of this study provide information on the type, amount and mechanism of formation of compounds resulting from heating carotenoids.

Identificationo f soy protein in meat by pyrolysis—high-resolution gas chromatography

Pyrolysis-gas chromatography was applied to the characterization of ground beef and soy protein isolate and its mixtures at the 50, 30 and 10% levels. A cryogenic trap pyrolysis mode was employed and the volatile pyrolysates were analysed by a high-resolution capillary gas chromatograph. Two phenolic derivatives, o-methoxy- and dimethoxyphenol, as well as 2,3-dithiabutane are uniquely observed at a large concentration in the soy pyrolysate. Quantification of these characteristic compounds allow the estimation of the level of soy inclusion in the mixture. This approach effectively denotes soy addition up to the 10% level in comminuted beef.

Isolation and identification of oxidation product of 2,6-Di-(tert-butyl)-4-methylphenol from polyethylene film

Abstract2,6-Di-(tert-butyl)-4-methylphenol is a widely used antioxidant in the production of polyethylene. An oxidation product of this antioxidant was isolated from aged polyethylene film and purified by preparative thin layer chromatography. This compound was identified as 3,3′, 5,5′-tetra-bis(tert-butyl)-stilbenequinone with the aid of IR- and mass spectroscopy. The generation of this oxidation product can lead to the discoloration of polyethylene film, and its formation can be catalyzed by contact with carbon black.