Fulong Wang

Effects of frying conditions on the formation of heterocyclic amines and trans fatty acids in grass carp (Ctenopharyngodon idellus).

The effects of frying temperature and the number of frying cycles on the formation of heterocyclic amines (HAs) and trans fatty acids (TFAs) in grass carp were investigated. 9t-18:1 FAs was detected in all samples. The TFA contents of samples fried at 150-210°C were not significantly different (P>0.05). The content and number of different types of HAs increased with increasing frying temperature. 9H-pyrido[3,4-b]indole (Norharman), 1-methyl-9H-pyrido [3,4-b]indole (Harman), and 2-amino-3,7,8-trimethylimdazo[4,5-f]quinoxaline (7,8-diMeIQx) were detected in most of the tested samples. The differences in the surface colour (ΔE) increased with frying temperature, and ΔE of samples fried at 170°C was significantly higher than that of 150°C (P<0.05). The analysis of different cycle times revealed that the TFA levels increased with an increase in the usage period of the frying fat, and 9t,12t-18:2 FAs was detected after the 40th frying cycle. As the number of frying cycles increased, the number of different types of HAs increased, seven types of HAs were detected after the 25th frying cycle.

Effects of frying and boiling on the formation of heterocyclic amines in braised chicken

Braised chicken is a traditional ready-to-eat poultry product produced by frying chicken coated with maltose or honey and then boiling it in a soup that is circularly used. This study examined the effects of the frying time, honey concentration, boiling time, and cycle times of the soup on the formation of heterocyclic amines (HA), a class of mutagenic/carcinogenic compounds generated in heated muscle meat. Nine HA in chicken and recycled soups were analyzed by HPLC with UV and fluorescence detection. 1-Methyl-9H-pyrido[3,4-b]indole (Harman), 9H-pyrido[3,4-b]indole (Norharman), and 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) were detected in most samples, and the amount of each HA increased with the frying or boiling time. Chicken skin was found to have higher HA content than chicken meat. More HA were detected in the soup than in the chicken, in most cases. 2-Amino-3-methylimidazo[4,5-f]quinoline and 2-amino-3,4,8-trimethylimidazoquinoxaline (4,8-DiMeIQx) were also detected in chicken and soup circularly boiled 20 times, and the total amount of HA reached 68.80 and 96.98 ng/g in chicken and soup, respectively.

Inhibitory Effect of Rosa rugosa Tea Extract on the Formation of Heterocyclic Amines in Meat Patties at Different Temperatures

In previous studies, heterocyclic amines (HCAs) have been identified as carcinogenic and a risk factor for human cancer. Therefore, the present study was designed to identify bioactive natural products capable of controlling the formation of HCAs during cooking. For this purpose we have evaluated the effect of Rosa rugosa tea extract (RTE) on the formation of HCAs in ground beef patties fried at 160 °C or 220 °C. RTE is rich in phenolic compounds and capable of inhibiting the formation of free radicals. The pyrido[3,4-b]indole (norharman) and 1-methyl-9H-pyrido[3,4-b]indole (harman) contents were significantly (p < 0.05) decreased in RTE-treated patties at 220 °C. 9H-3-Amino-1-methyl-5H-pyrido[4,3-b]indole acetate (Trp-P-2) and 3-amino-1,4-dimethyl-5H-pyrido-[4,3-b]indole acetate (Trp-P-1) were not detected at 160 °C and were statistically (p < 0.01) reduced at 220 °C compared to the control. RTE remarkably inhibited the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) at 220 °C (p < 0.001) and at 160 °C (p < 0.05). 2-Amino-9H-pyrido[2,3-b]indole (AαC) and 2-amino-3-methyl-9H-pyrido[2,3-b]-indole (MeAαC) were only detected in the control group at 160 °C but were comparatively (p > 0.05) similar in the control and treated groups at 220 °C. 2-Amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), and 2-amino-3,4,8-trimethylimidazo[4,5-f]-quinoxaline (4,8-DiMeIQx) were not detected in any sample. Total HCAs were positively correlated with cooking loss. In the RTE-treated groups, 75% of the total HCAs were decreased at 160 °C and 46% at 220 °C, suggesting that RTE is effective at both temperatures and can be used during cooking at high temperatures to lessen the amount of HCAs formed.

Potential use of crude extracts from Alaska Pollock muscle as meat tenderizer

The activity of crude extracts from Alaska Pollock muscle responsible for the hydrolysis of myofibrils and perimysia from beef Longissimus Dorsi muscle was investigated. The results showed that myosin heavy chain and myosin light chain were hydrolyzed completely after 12 h of incubation. Tropomyosin, α-actinin, and troponin-T disappeared after 24 h of incubation, whereas the actin was partially degraded. The collagen fibers were so loose that cross-linking among microfibrils occurred after treatment with the crude extracts. Meanwhile, the second structures of myofibrillar proteins were not changed markedly after incubation. The α-helices in perimysia treated with the crude extracts were partially transformed into β-sheets, while the β-turn and the random coil fractions were steady. It was concluded that myofibrils and perimysia from beef Longissimus Dorsi muscle were commendably hydrolyzed by the crude extracts from Alaska Pollock muscle, so that the crude extracts from Alaska Pollock muscle could be utilized as a potential meat tenderizer.

Mechanism of Polyphosphates Hydrolysis by Purified Polyphosphatases from the Dorsal Muscle of Silver Carp (Hypophthalmichthys Molitrix) as Detected by 31P NMR

UNLABELLED The dynamic hydrolysis of tetrasodium pyrophosphate (TSPP), sodium tripolyphosphate (STPP) and polyphosphate compound, which was catalyzed by purified pyrophosphatase (PPase) and myosin- tripolyphosphatase (TPPase) from the silver carp dorsal muscle, was studied using (31) P NMR spectroscopy. In the PPase + TSPP system, the pyrophosphate (PP) was hydrolyzed quickly and completely within 8 h and the hydrolysis rate of PP was 12.51%/h. In the TPPase + STPP system, the first-order hydrolysis of tripolyphosphate (TPP) was not yet complete after 48 h, and the derived PP accumulated progressively. Given the coexistence of PPase and TPPase, only 1.20% of TPP in STPP alone remained after 48 h. However, the generation rate of Pi in the polyphosphate compound (TSPP: STPP: sodium hexametaphosphate = 1: 8: 1) was 0.76%/h, which was less than 0.88%/h in STPP alone. In the presence of polyphosphatases, the decrease of PP or TPP content in the polyphosphate compound was not as rapid as that in TSPP or STPP alone due to the inhibitory effect of PP on TPPase and the effect of low system pH on PPase. The understanding of polyphosphates hydrolysis mechanism was capable of developing the advanced polyphosphate mixture in order to reduce the phosphate residue in fish products. PRACTICAL APPLICATION Processors appreciate the proven value of phosphates to increase the yield and functionality of the fish meat products. Our studies showed that the hydrolysis rate of PP or TPP in the blend was slower than that of polyphosphate alone. Thus, it is likely that the addition of PP and TPP in a polyphosphate blend had a prolonged interaction with proteins in fish meat processing and the effectiveness of polyphosphates was enhanced.

Technical note: The effect of carcass deboning technique on the meat quality of cattle

The objective of this study was to evaluate the effects of the suspended carcass deboning technique on the meat attributes of electrically stimulated cattle ( = 10). A carcass deboning technique that removes the main bones without breakdown of the entire carcass was applied to suspended sides soon after slaughter. After 3 d of aging at 4°C, the shear force of the rectus femoris, longissimus lumborum, and supraspinatus muscles of the suspended carcass deboning technique was reduced by 27%, 29%, and 23% ( < 0.05), respectively. The carcass deboning technique increased the sarcomere length by 14%, 10%, and 16% ( < 0.05), and the myofibril fragmentation index was increased by 10%, 5%, and 13% ( < 0.05), respectively, for the same 3 muscles. There was no difference in the pH, color, or cooking loss between the treatment and the control ( > 0.05). The carcass deboning technique could be a viable approach to improve beef tenderness with a relatively short aging duration.