Changes in free amino acids and biogenic amines of Egyptian salted-fermented fish (Feseekh) during ripening and storage

The aim of this study was to investigate changes in the formation of amino acids and biogenic amines in Egyptian salted-fermented fish (Feseekh) during ripening (20 days) and storage (40–60 days). The total concentration of free amino acids increased from 8 (dry weight; DW) to 72 g/kg (DW) after 60 days of storage. The predominant free amino acids were leucine, glutamic acid, lysine, alanine, valine, aspartic acid, isoleucine and citrulline. Their concentrations accounted for 68% of the total concentration of amino acids after 60 days. The total contents of biogenic amines ranged from 84 to 1633 mg/kg (DW) during the investigated period. Cadaverine was the major amine detected in Feseekh at all sampling stages and its concentration varied between 21 and 997 mg/kg (DW). The histamine content (211 mg/kg DW) only exceeded the maximum tolerance level (200 mg/kg) after 60 days. It could be concluded that Feseekh can be consumed without any health risks between 20 and 40 days but it can be hazardous after 60 days due to the biogenic amine content.     

Application of polysaccharide enzymes in sugar cane bagasse

Commercial cellulase, hemicellulase, and pectinase enzymes were applied to hydrolyse sugar cane bagasse. Cell wall polysaccharides of this substrate were hydrolysed extensively. Maximum hydrolysis is obtained when commercial hemicellulase and pectinase are combined with cellulases. The digests were chromatographed by high performance liquid chromatography in order to obtain information upon the structure features of bagasse polysaccharides.     

Reduced biogenic amine contents in sauerkraut via addition of selected lactic acid bacteria

The contents of free amino acids and biogenic amines in spontaneously fermented sauerkraut, inoculated or not with specific lactic acid bacterium strains, were monitored throughout 45 d of storage. The strains tested were Lactobacillus plantarum 2142, Lactobacillus casei subsp. casei 2763 and Lactobacillus curvatus 2771. In both the control and the experiments, the total amino acid contents increased with time – and the predominant ones were aspartic acid, arginine and glutamic acid. However, upon inoculation with either strain, the total biogenic amine contents remained considerably lower than those of the control (especially in the cases of L. casei subsp. casei and L. curvatus); every single biogenic amine was actually below the 100 ppm-threshold. The dominant biogenic amines in the control were putrescine – and tyramine and histamine, to a lesser extent; the putrescine content was 10-fold lower if inoculation had taken place with either lactobacillus tested; and histamine and tyramine were essentially absent during storage, whereas they ranked above 200 ppm in the control by 45 d. Hence, an efficient food-grade biological tool was made available that constrains buildup of dangerous biogenic amines in fermented vegetables during storage.     

Effect of foaming parameters on the physical and phytochemical properties of tomato powder

Food Science and Biotechnology - The objective of this work was to study the effect of foaming parameters on the physical and phytochemical properties of tomato powder. A central composite...     

Biogenic amine contents in selected Egyptian fermented foods as determined by ion-exchange chromatography

Biogenic amines in foods may pose a public health problem. Therefore, histamine, tyramine, putrescine, cadaverine, spermine, and spermidine concentrations were measured in selected food items commonly consumed in Egypt. Foods examined were dairy products (blue cheese and Mesh cheese), meats (fermented and smoked cooked sausage), and fish (smoked and salted fermented fish [Feseekh], salted sardines, and anchovies). Egyptian fermented sausage had the highest concentration of total biogenic amines (2,482 mg/kg), followed by Mesh cheese (2,118 mg/kg) and blue cheese (2,084 mg/kg). The lowest concentration was found in smoked cooked sausage (111 mg/kg). Histamine was found at a high level (521 mg/kg) in Feseekh, and tyramine was highest (2,010 mg/kg) in blue cheese. These results indicate that some traditional Egyptian foods may pose a health risk due to the concentration of biogenic amines, especially histamine.     

Studies on Purification and Kinetics of Glucose Isomerase on Hydrolysates of Starch

Glucose isomerase was produced from Streptomyces phaeochromogenes by aerobic fermentation at 28°C for 24 h. The crude enzyme was obtained by disintegrating the harvested cells. Ammonium sulphate at a saturation of 0.65 gave the maximum enzyme recovery 89.4%) from the crude extract, while acetone gave 66.4% at a concentration of 3/1 (v/v). The crude enzyme extract was purified by concentration, dialysis, precipitation with ammonium sulphate, passing through a column of Amberlite, and then the eluate was treated with acetone to precipitate the enzyme. The kinetic behavior was studied and it was found that optimum D -glucose concentration was 0.8-M . No change in K_m value was observed, while V_max was affected.