Effect of tannic acid and kiam wood extract on lipid oxidation and textural properties of fish emulsion sausages during refrigerated storage

Effects of dietary tannic acid on the growth, hepatic gene expression, and antioxidant enzyme activity in Brandt's voles (Microtus brandti)

This study was designed to investigate the physiological and biochemical responses of Brandt's voles to the persistent presence of dietary tannic acid. The diet for animals in the experimental group was supplemented with 3% dietary tannic acid for 5weeks. The control group received a commercial lab chow. No significant differences were detected in body weight, organ (heart, kidney, and liver) weights, and organ parameters between animals from two groups. However, voles in the experimental group had significantly higher daily food intake, increased contents of proline and histidine in saliva and feces after protein hydrolysis, and elevated hepatic expression of transferrin than the control. Our results suggested the existence of adaptive strategies developed in Brandt's voles to overcome the adverse effects of dietary tannic acid. (1) Food consumption was increased to satisfy their nutritional demands. (2) The secretion of tannic-acid-binding salivary proteins was promoted. (3) The absorption of iron was enhanced. These alterations contributed to neutralize the negative effects of tannic acid and maintain body mass in animals supplemented with tannic acid. As the result of the consumption of tannic acid, hepatic expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase was significantly decreased, while the overall potential of the antioxidant system, characterized by increased hepatic enzymatic activities of catalase and glutathione peroxidase, was enhanced. Our results also implied the involvement of tannic acid in the regulation of lipid metabolism and oxidative stress in voles.

Alleviative effects of litchi (Litchi chinensis Sonn.) flower on lipid peroxidation and protein degradation in emulsified pork meatballs

To avoid or retard the lipid peroxidation of meat products, antioxidants are commonly added. Considering the safety and health of additives in meat products, consumers prefer natural antioxidants rather than synthetic ones. Gentisic acid and epicatechin were identified as the major phenolic acid and flavonoid, respectively, of litchi flowers (LFs). The physicochemical properties of pork meatballs with or without dried LF powders (0.5%, 1.0%, and 1.5%, w/w) and tert-butylhydroquinone (TBHQ; 0.01%, w/w) were analyzed during a 4-week frozen storage period. LF and TBHQ decreased (p < 0.05) thiobarbituric acid reactive substance (TBARS) values but increased (p < 0.05) thiol group contents in meatballs. LF added to meatballs improved (p < 0.05) texture and water-holding capacity (centrifugation/purge losses) more than in the control group upon the storage. Although LF powders made meatballs redder and darker (p < 0.05) than the control and TBHQ groups, they did not affect the preference of panelists. The addition of 0.5% LF powders exhibited the best (p < 0.05) overall sensory panel acceptance. LFs may be an effective natural antioxidant to reduce lipid and protein oxidation for frozen cooked meat products.

Effect of the Addition of Schisandra chinensis Powder on the Physico-chemical Characteristics of Sausage

The individual and interactive effects of Schisandra chinensis powder (SCP) and sodium nitrite additions on color, pH, water holding capacity, residual nitrite, 2-thiobarbituric acid reactive substances (TBARS), volatile basic nitrogen, texture properties, fatty acids, amino acids and sensory evaluation of cooked pork sausages were investigated after 20 d of storage at 4°C. The powders (0, 0.5 and 1.0%) were added to sausages either alone or in combination with nitrite (0 and 100 ppm). SCP added-sausages showed lower L* (lightness) and W (whiteness) values, and higher b* (yellowness) values than sausage containing no nitrite, and exhibited the highest a^* values at a 0.5% addition (p<0.05). Residual nitrite and TBARS values were found to be significantly reduced as the addition levels of SCP increased (p<0.05). As the addition of SCP increased, the sausage showed gradually decreased brittleness, cohesiveness, springiness, gumminess and chewiness, while adhesiveness increased. Polyunsaturated fatty acid, n-6 and n-6/n-3 fatty acid ratio concentrations were significantly higher in sausages containing SCP (p<0.05). The addition of SCP to sausage significantly (p<0.05) increased the ammonia content (by 0.5% SCP) and aromatic amino acid concentrations (by 1.0% SCP) (p<0.05). Inclusion of SCP in sausage meat resulted in a significant deterioration in quality characteristics of flavor, springiness, juiciness and overall acceptability (p<0.05). As expected, the observed changes in a*, W, pH, shear force, texture property, TBARS, fatty acid, amino acid and sensory score of sausages, depended on the rate of addition of nitrite (p<0.05). These results suggest that SCP addition is not an effective way of improving the sensory evaluation of sausages, but may beneficially affect TBARS, nitrite scavenging activity, fatty acid and amino acid content in pork sausages.

Frozen storage stability of beef patties incorporated with extracts from ulam raja leaves (Cosmos caudatus)

In Malaysia, fresh ulam raja leaves (Cosmos caudatus) are eaten raw with rice. In this study, beef patties incorporated with extracts of ulam raja (UREX) and commercial green tea extract (GTE) added individually at 200 and 500 mg/kg were stored at -18°C for up to 10 weeks. Lipid oxidation, cooking yield, physicochemical properties, textural properties, proximate composition and sensory characteristics of the beef patties were compared between those incorporated with UREX, GTE and the control (pure beef patty). Incorporation of UREX or GTE at 500 mg/kg into beef patties reduced the extent of lipid oxidation significantly (P<0.05). UREX showed a strong lipid oxidation inhibitory effect, comparable with GTE. In addition, a significant improvement (P<0.05) in cooking yield and textural properties was also recorded. However, incorporation of UREX and GTE into beef patties showed no significant influence (P>0.05) on the colour, pH, proximate composition and overall sensory acceptability of the patties.

Effect of sage (Salvia officinalis) on the oxidative stability of Chinese-style sausage during refrigerated storage

The objective of this study was to assess the effect of sage, at levels of 0.05%, 0.1% and 0.15% (w/w), on the oxidative stability of Chinese-style sausage stored at 4°C for 21 days. The results showed that inclusion of sage in sausages resulted in lower L* values (P<0.05) and higher a* values (P<0.05) compared to the control. During refrigerated storage, sausages containing sage showed significantly retarded increases in TBARS values, and in the formation of protein carbonyls (P<0.05), but showed accelerated losses of thiol groups (P<0.05). Addition of sage to the sausages at levels of 0.1% and 0.15% reduced textural deterioration during refrigerated storage (P<0.05). Sage used in this study had no negative effects on the sensory properties of sausages.