Chinese red pepper (Zanthoxylum bungeanum Maxim.) leaf extract as natural antioxidants in salted silver carp (Hypophthalmichthys molitrix) in dorsal and ventral muscles during processing

Chinese red pepper (Zanthoxylum bungeanum Maxim.) leaf (ZML) extract contains high amounts of phenolic compounds possessing high total antioxidant capacity and hydroxyl, 1, 1-dipheny-2-picrylhydrazyl (DPPH) free radical scavenging activity. ZML extract was investigated as a natural antioxidant for the lipid stability of salted silver carp (Hypophthalmichthys molitrix) throughout salting and drying. Both dorsal and ventral muscles were examined for differences in moisture content, salt content, total lipid content, and degree of lipid oxidation. The hexanal content, Thiobarbituric acid reactive substances (TBARS) value, and lipoxygenase (LOX) activity in the ventral muscle were significantly higher than those of the dorsal muscle (p < 0.05). In the treatments with ZML extract, the hexanal content, the TBARS value, and the LOX activity were significantly lower (p < 0.05) during processing both in the dorsal and ventral muscles. The sensory qualities of processed salted fish could be improved with the amount of 0.030% extract in the dorsal muscle and 0.045% extract in the ventral muscle. These results showed that ZML extract can be a source of natural antioxidants and used as a food additive.     

Effects of Added Phosphates on Lipid Stability During Salt Curing and Rehydration of Cod (Gadus morhua)

Effects of added phosphates on retardation of lipid oxidation of salted cod during processing, storage and after rehydration were investigated. Lipid hydrolysis progress and development of color, primary and secondary lipid oxidation products and fluorescence intensities were determined. Added phosphates significantly retarded lipid hydrolysis and lipid oxidation progress, resulting in lower free fatty acid , lipid hydroperoxides (PV), thiobarbituric acid-reactive substances (TBARS) as well as fluorescence intensities (δF _or and δF _aq). Significant correlation between the lipid oxidation products (PV, TBARS, δF _or and δF _aq) and yellow/brownish discoloration (b* value) of salted cod was observed. Principal component analysis showed that TBARS, b* value and δF _or were the strongest indicators of lipid oxidation during salting and storage.     

N-nitrosamine reduction in salted and fermented anchovy sauce by ionizing irradiation

Salted and fermented anchovy sauce spiked with or without N-nitrosodimethylamine (NDMA) and N-nitrosopyrrolidine (NPYR) was irradiated at 0, 5, 10, 15 and 20 kGy. NDMA and NPYR reduction by irradiation was not observed in non-spiked samples at 0 week, while a significant reduction was observed after 4 weeks of storage at 15 °C (P<0.05). In N-nitrosamine spiked samples, a positive effect of irradiation on NDMA and NPYR reduction was observed. NDMA and NPYR levels were decreased by irradiation at 5 kGy or above after storage. Therefore, gamma irradiation has a possibility to reduce N-nitrosamines in salted and fermented anchovy sauce.     

Effect of ascorbic acid and citric acid on the quality of salted Chinese cabbage during storage

Changes in color, browning indices, enzyme activity, and physical and chemical quality during the storage period were investigated to assess the effectiveness of storage period extension along with the addition of ascorbic acid (AA) and citric acid (CA) to salted Chinese cabbage. After 16 days of storage, the change in chromaticity value showed treatment with 0.5% CA showed the lowest change in the brown index during the storage period. The control showed the highest residual activity of polyphenol oxidase among control, AA, and CA-treated salted cabbage. AA and CA treatment effectively inhibited the initial populations of microorganisms including total aerobic bacteria, lactic acid bacteria, and yeast and molds in salted Chinese cabbage during storage. Further, the texture, i.e., hardness, chewability, and elasticity, tended to decrease with increasing storage. These results suggest that treatment with AA could help maintain the quality of salted Chinese cabbage during the storage period.     

Analysis of the cultivable bacterial community in jeotgal, a Korean salted and fermented seafood, and identification of its dominant bacteria

Jeotgal or jeot, a traditional Korean salted and fermented food, is made by adding 20-30% (w/w) salt to various types of seafood. To develop a more complete overview of the bacterial community present in jeotgal, 610 pure colonies were isolated from Myeolchi-jeot and Saeu-jeot, the most commonly consumed varieties of jeotgal, which are made with anchovy (Engraulis japonicas) and tiny shrimp (Acetes japonicas), respectively. The bacterial isolates were identified by 16S rDNA sequence analysis. A total of 104 species comprising 47 genera and 31 previously unknown species were identified. Eleven genera were isolated from both jeotgal samples, including species in the genera Staphylococcus, Bacillus, Halomonas, and Kocuria, with Staphylococcus spp. constituting the highest number. The most populous genus detected in Myeolchi-jeot was Bacillus and its relatives, while the most populous in Saeu-jeot was Staphylococcus. These were isolated from both jeotgal samples, but their proportion in the bacterial community may be influenced by matrix composition and fermentation parameters. Among the proteolytic isolates, although Virgibacillus halodenitrificans KM2100 and Staphylococcus spp. maintained their growth in 20% NaCl, protease activities were not detected in these conditions. This suggests that bacteria are not the major source of the proteolytic enzyme involved in protein hydrolysis in high-salt-containing jeotgal. However, the Staphylococcus spp. isolated from Saeu-jeot were too numerous for us to ignore their possible role in jeotgal fermentation. Staphylococcus spp. may not be hugely involved in proteolysis, but they may play a significant role in the ripening of jeotgal. Bacteria of the genus Bacillus and its relatives and of the genus Staphylococcus may be the major organisms involved in jeotgal fermentation.     

Histamine contents of salted seafood products in Taiwan and isolation of halotolerant histamine-forming bacteria

Fifty-seven salted seafood products sold in the fishing village stores in Taiwan, including salted fish product, salted mollusc product and salted shrimp product, were tested to determine the occurrence of histamine and histamine-forming bacteria. Although the average content of each of nine different biogenic amines in all samples was less than 5.0 mg/100 g, 10.5% (6/57) of tested samples had the histamine content greater than the 5.0 mg/100 g allowable limit suggested by the US Food and Drug Administration. One histamine-producing bacterial strain, capable of producing 78.5 ppm of histamine in trypticase soy broth supplemented with 1.0% l-histidine (TSBH), was identified as Bacillus megaterium. The B. megaterium isolate was a halotolerant bacterium which grew well to an elevated NaCl concentration of 15% in TSBH medium. Besides, it had a consistent ability to produce >300 ppm of histamine at 10% NaCl concentration in TSBH medium after 72 h.     

盐渍Shuan头新工艺

对Shuan头盐渍工艺进行了改进，以色泽（感官目测和色差仪比色）、硬度、Vc、蛋白质和总糖为测定指标，考察了12种可能影响盐渍Shuan头品质的因素，并通过正交实验确定了最佳工艺参数，使盐渍Shuan头在能够保证色泽和硬度指标的同时又能尽可能减少营养成分的损失。     

Influences of potassium ferrocyanide on lipid oxidation of salted cod (Gadus morhua) during processing, storage and rehydration

The effects of added potassium ferrocyanide (CN) in different concentrations (2.5 ppm, 7.5 ppm and 100 ppm), in salt, on lipid oxidation in cod during salting, storage and rehydration were examined in this study. An increase in CN concentration accelerated lipid oxidation of the salted cod, as observed by increases in lipid hydroperoxides (PV) and thiobarbituric acid-reactive substances (TBARS), as well as in the development of fluorescence compounds (δF_or and δF_aq). A yellow discolouration (higher b^∗ value) of salted cod was associated with higher levels of oxidation derivatives. High correlation between PV, TBARS and free fatty acid (FFA), as well as between FFA and δF_or, was found. The results of principal component analysis showed that TBARS, b^∗ value and δF_or were the strongest indicators of lipid oxidation during salting and storage.     

Survival of Escherichia coli O157:H7 in yogurt drink, plain yogurt and salted (tuzlu) yogurt: Effects of storage time, temperature, background flora and product characteristics

The survival of Escherichia coli O157:H7 at 4 and 22°C in yogurt drink, plain yogurt and salted yogurt (yogurt native to Hatay, Turkey) was studied. Total aerobic plate count (TPC), total mould and yeast count, pH and titratable acidity during the storage period were measured. pH and TPC count of the samples at 22°C were significantly higher than those of samples at 4°C ( P <  0.01). E. coli O157:H7 survived in the products at both 4 and 22°C, whereas survival of E. coli O157:H7 was significantly lower at 4°C than at 22°C ( P <  0.05). Multiple linear regression models were used to determine factors affecting the survival of E. coli O157:H7.     

Experimental investigation on solar drying of salted greengages

The preserved greengage is a favorite dried fruit in China. In processing preserved greengages, the drying of salted greengages is a key and energy-consuming process. Traditionally, the drying of salted greengages mainly relies on natural sun drying and requires about 48 days. In this study, an attempt was made using solar driers with fresh fruit that have been mixed with some salt and preserved in a concrete pool for more than 2 months. A solar drier, consisting of 6 m² of solar air collectors, a greenhouse-like drying chamber and three fans powered by a solar module of 20W_p, was developed and examined, and a comparative experiment between solar drying and natural sun drying was conducted from 26 April to 12 June, 2003. The experiment found that, even in cloudy days, the temperature of the drying air inside the chamber was much higher than that of the ambient air, and solar drying of salted greengages was very effective. Thus the drying period was shortened from 48 days in natural sun drying to about 15 days. It was also found that the solar drying could eliminate a process that takes 20 days to desalt salted greengages to obtain the final product as required in the natural sun drying method.