Physical and chemical characteristics,major fatty acids,antimicrobial activity and toxicity analysis of red shrimp (Metapenaeus brevicornis) brain lipid

Physical and chemical characteristics of red shrimp (Metapenaeus brevicornis) brain lipid have been determined by standard methods. Through GLC analysis, caprylic, myristic, palmitic, stearic and oleic acids have been found as the five major fatty acid components of M. brevicornis brain lipid. The lipid has found active against disease causing bacteria Shigella dysenterial, Salmonella typhi and Staphylococcuss aureus, and fungal pathogens Macrophomina phascolma, Alternaria alternate and Curvularia lunata. By applying on predatory fishes, Heteropneustes fossilis and Anabas testudineus, different extracts of M. brevicornis brain lipid have showed a minimal toxic effect.     

Physicochemical properties of a fibrous fraction from chia (Salvia hispanica L.)

An evaluation was done of some physicochemical properties of a fiber-rich fraction (FRF) obtained by dry processing of defatted chia (Salvia hispanica) flour. The fiber-rich fraction (FRF) had 29.56 g/100 g crude fiber content and 56.46 g/100 g total dietary fiber (TDF) content, of which 53.45 g/100 g was insoluble dietary fiber (IDF) and 3.01 g/100 g was soluble dietary fiber (SDF). The FRF water-holding capacity was 15.41 g/g, its water absorption capacity 11.73 g/g, and its organic molecule absorption capacity 1.09 g/g. The FRF also had low oil-holding (2.02 g/g) and water adsorption (0.3 g/g) capacities. Emulsifying activity in this fraction was 53.26% and emulsion stability was 94.84%. Its evaluated antioxidant activity was 488.8 μmol/L Trolox equivalents/g FRF, which is higher than for many cereals and similar to drinks such as wine, tea, coffee and orange juice. The chia FRF values for the evaluated properties, particularly for water-holding, oil-holding and organic molecule absorption capacity, suggest it could be a useful ingredient in dietetic products such as baked and fried foods, among others.     

Effect of Lactobacillus plantarum and chitosan in the reduction of browning of pericarp Rambutan (Nephelium lappaceum)

The effects of Lactobacillus plantarum alone or in combination with chitosan were evaluated on quality and color retention in rambutan fruits (Nephelium lappaceum) stored at 25 °C and 10 °C with 75 ± 2.5% of relative humidity for 10 and 15 days, respectively. The development of the microorganisms was evidenced by viability analyses and lactic acid production. The application of L. plantarum significantly improved color retention (a* and L*), and reduced weight losses. The lactobacilli, alone or in combination with chitosan, preserved fruit quality characteristics such as firmness, total soluble solids and titratable acidity. The lactobacilli application on rambutan pericarp produced acidification of pericarp and avoided the browning; thereby desiccation was prevented due to biofilm formation.     

Physico-chemical characterization of fungal chitosan from shiitake stipes

Fungal chitosan was prepared by alkaline N-deacetylation of crude chitin obtained from air-dried shiitake stipes. The yields of precipitated and soluble chitosans were 218.4-240.3 and 69.3-83.4 mg/g, respectively. The degrees of N-deacetylation (DD) of precipitated chitosans increased with the prolonged reaction time and reached 90.18% at 120 min. The average molecular weights (MW) of both chitosans decreased with the prolonged reaction time. The lightness and whiteness index values of precipitated chitosans were higher than those of soluble chitosans. After N-deacetylation, carbon and nitrogen contents and N/C ratios of chitosans significantly increased. The endothermic and exothermic peak temperatures of precipitated chitosans were higher than those of soluble chitosans. Two characteristic crystalline peaks for precipitated chitosans were at 2θ=9.65° and 19.87° and three WAXD patterns were similar. Under electron microscopic examination, both chitosans showed the aggregated flakes with dense and firm structure and without porosity. Generally, both chitosans prepared showed different physico-chemical characteristics as evidenced by the DD, MW, element analysis, DSC, WAXD and SEM patterns.     

Physicochemical characterization and functional properties of galactomannans from mesquite seeds (Prosopis spp.)

In the present study, the physicochemical and functional characteristics of galactomannans (GM) from mesquite seeds were investigated and compared with the characteristics of a commercial GM. The mesquite gum was extracted with water at room temperature, and its physicochemical parameters, thermal constants and functional properties were determined. The results showed that mesquite GM had contents of 2.56% moisture, 4.54% protein and 0.06% ash; trace levels of fat; 95.40% total carbohydrate; +63.48 optical rotation; an intrinsic viscosity of 12.36 dL/g and a molecular weight of 1.2 × 10⁶ g/mol. The sugars detected were mannose (Man) and galactose (Gal), with a Man:Gal ratio of 1.50. The curves obtained by calorimetry indicated a transition temperature (Tg), melting temperature (Tm) and heat capacity (Cp) very similar to those of the guar GM. The evaluation of the functional properties of the mesquite GM revealed a solubility of 92.10%, an emulsion capacity of 95% and an emulsion stability of 92.24%. The polysaccharide extracted from the mesquite seeds is a GM with physicochemical and functional properties similar to those reported for other legume seed gums, allowing us to conclude that mesquite GM has the potential for use in the food industry.     

Isolation, purification and characterization of a new gum from Acanthophyllum bracteatum roots

A new gum was isolated from the roots of Acanthophyllum bracteatum (ABG) by warm-water extraction. Purification was carried out by barium complexing to give a yield of 12.4% of pure air-dried or 5.8% of freeze-dried gum. The ABG contained 13.2% moisture, 84.3% carbohydrate, 0.9% protein and 1.5% ash. Its mineral content was comparable to commercial hydrocolloids. Monosaccharide analysis by HPLC showed the presence of galactose, glucose, arabinose, rhamnose and uronic acids in the ratio 16.0:7.2:3.0:1.0:3.1 respectively. The viscosity and pH value of 1% ABG solution at 25 °C were 51.5 mPa s and 6.85 respectively. ABG solutions (5-30 wt%) showed shear-thinning flow behavior at shear rates < 10 s⁻¹. The viscosity decreased as temperature increased, and was highest at the neutral state. ABG had low surface and emulsification properties but moderate foaming capacity and relatively high foaming stability, which suggests that ABG could potentially be used in food systems to improve foaming properties.     

Antioxidant Parkia speciosa pod powder as potential functional flour in food application: Physicochemical properties’ characterization

Chemical, physicochemical and functional properties of fibrous materials from freeze dried (FDPSP) and oven dried (ODPSP) Parkia speciosa pod (PSP) were evaluated in order to examine the potential applications in food. Preliminary screening of PSP using scanning electron microscope showed that PSP consisted of starches and fibres. Proximate analysis showed that both samples consisted of 4.3–5.2% of moisture, 9.5–10.7% of protein, 0.1–0.2% of fat, 0.01% of ash, 16.5–16.8% of crude fibre and 68.3–68.7% of carbohydrates. However, different functional properties were shown in these samples. FDPSP gave a lighter colour compared to ODPSP. Higher values of solubility (30.8%), water- and oil-holding capacities (3.72 and 1.55 g/g, respectively) were found in FDPSP. Conversely, higher emulsifying activity of 62.7% with high emulsion stability of 99.9% was shown in ODPSP. Higher antioxidative properties were also shown in FDPSP which consist TPC of 110.0 mg gallic acid equivalent/g sample and TFC of 8.5 mg pyrocatechol equivalents/g sample. These extracts (pre-diluted 50×) gave %DPPH_sc, %ABTS_sc and FRAP values of 65.3%, 77.4% and 1.9 mM FeSO₄, respectively. Therefore, it was suggested that PSP has the potential in producing functional fibres that could be imparted into the food system.     

Biochemical characterization and process stability of polyphenoloxidase extracted from Victoria grape (Vitis vinifera ssp. Sativa)

Polyphenol oxidase (PPO) was isolated from Victoria grapes (Vitis vinifera ssp. Sativa) grown in South Africa and its biochemical characteristics were studied. Optimum pH and temperature for grape PPO activity were pH 5.0 and T = 25 °C with 10 mM catechol in McIlvaine buffer as substrate. PPO showed activity using the following substances: catechol, 4 methyl catechol, d, l-DOPA, (+) catechin and chlorogenic acid. K_m and V_max values were 52.6 ± 0.00436 mM and 653 ± 24.0 OD_400 nm/min in the case of 10 mM catechol as a substrate. Eight inhibitors were tested in this study and the most effective inhibitors were found to be ascorbic acid, l-cysteine and sodium metabisulfite. Kinetic studies showed that the thermal inactivation of Victoria grape PPO followed first-order kinetics, with an activation energy, E_a = 225 ± 13.5 of kJ/mol. Both in semipurified extract and in grape juice, PPO showed a pronounced high pressure stability.     

Physicochemical and structural characterization of Lima Bean (Phaseolus lunatus) globulins

A globulin fraction from Phaseolus lunatus have been isolated and characterized. The fractionation scheme used allowed to obtain a Globulin partially purificated. Globulin purification by ultracentrifugation allowed to isolate three peaks with different sedimentation coefficient, while gel filtration chromatography yielded two species, I and II, which were later identified as 11S and 7S globulins, respectively. Species II, 7S globulin from P. lunatus, seems to have a molecular mass of 72 kDa and to be constituted by polypeptides of 34-36, 25-27 and 16-18 kDa without intermolecular disulfide bonds. These polypeptides would present certain heterogeneity, as suggested by the results of isoelectric focusing and electrophoresis analyses. This protein exhibited some particular features, including a lower molecular mass and higher thermal stability than typical vicilins. Species I, with a molecular mass of 336 kDa, would be constituted by subunits of 53-55 and 40-41 kDa formed by smaller polypeptides (around 30 and 20 kDa) linked by disulfide bonds. These features, together with the existence of basic and acid polypeptides in the molecule, would confirm that species I is a globulin of the legumins, 11S globulins or α-conglutin family.     

Short communication: Biofilm production characterization of mecA and mecC methicillin-resistant Staphylococcus aureus isolated from bovine milk in Great Britain

Staphylococcus aureus is an important cause of contagious intramammary infection in dairy cattle, and the ability to produce biofilm is considered to be an important virulence property in the pathogenesis of mastitis. The aim of this study was to characterize the biofilm formation capacity of methicillin-resistant Staph. aureus (MRSA), encoding mecA or mecC, isolated from bulk tank milk in Great Britain. For this purpose, 20 MRSA isolates were grown on microtiter plates to determine the biofilm production. Moreover, the spa-typing and the presence of the intercellular adhesion genes icaA and icaD were analyzed by PCR. All MRSA isolates tested belonged to 9 spa-types and were PCR-positive for the ica genes; 10 of them (50%) produced biofilm in the microtiter plate assay. This is also the first demonstration of biofilm production by mecC MRSA.     

Physicochemical characteristics and production of whole soymilk from Monascus fermented soybeans

Monascus fermented soybeans (MFS) were prepared by solid state fermentation. MFS showed higher solubility than the unfermented control within the acidic pH region but showed the opposite trend at pH 7 and 9. Although the emulsifying activity index of MFS was lower than that of the control, MFS had significantly higher emulsion stability at pH 7 and 9. Significant protein hydrolysis took place during fermentation, and the proportion of peak area less than 1.35 kDa was greatly increased in MFS. Whole soymilk prepared from MFS contained monacolin K (475 μg/g), and was enriched in isoflavone aglycones. Neither homogenisation nor pasteurisation caused significant changes in the isoflavone and monacolin K contents of the Monascus fermented soymilk. Total phenol content and ABTS radical scavenging activity were significantly higher in the Monascus fermented soymilk than in the control soymilk.     

Physicochemical and functional properties of the protein isolate and major fractions prepared from Akebia trifoliata var. australis seed

The physicochemical and functional properties of protein isolate (API) and major protein fractions prepared from Akebia trifoliata var. australis seed were investigated. The seed contained 38.83% of oil and 17.23% of protein. Albumin (51.65%) and glutelin (46.40%) were the predominant fractions in the protein component of the seed. The major amino acids were found to be glutamic acid and aspartic acid, while the contents of sulphur-containing amino acids and threonine were very low. One to eight distinct bands with molecular weight (MW) ranging from 12.0 to 50.0 kDa were displayed by SDS–PAGE. The solubilities of API, albumin and glutelin from seeds of the A. trifoliata var. australis were the lowest at pH 4.0–5.0. The high surface hydrophobicity indices of these three proteins were observed at pH 7.0, while the excellent emulsifying properties were displayed at pH 9.0. Circular dichroism measurements indicated that API, albumin and glutelin were rich in β-strand and random coil structures.     

Molecular characterization of antibiotic resistant Salmonella isolates from Indian foods

Salmonella isolates belonging to five serovars, Salmonella enterica Ohio, S. Oslo, S. Tennessee, S. Weltevreden and S. Typhimurium, isolated during 2006-2008 from food samples like sprouts and different varieties of fresh water and marine fish were tested for antibiotic resistance. High percentages (97%) of the isolates were resistant to at least one antibiotic and 82% of the isolates were resistant to more than one antibiotic. S. Oslo was the most resistant serovar and it exhibited resistance to 13 out of 16 antibiotics tested. Integron 1, which has been shown to confer multidrug resistance to various Salmonella serovars, was detected in multidrug resistant S. Oslo. PFGE studies revealed that serovars showed very high genetic diversity. The multidrug resistant S. Oslo showed unique PFGE pattern, which could be used in epidemiological studies.     

Isolation and characterization of a novel analyte from Bacillus subtilis SC-8 antagonistic to Bacillus cereus

In this study, an effective substance was isolated from Bacillus subtilis SC-8, which was obtained from traditionally fermented soybean paste, cheonggukjang. The substance was purified by HPLC, and its properties were analyzed. It had an adequate antagonistic effect on Bacilluscereus, and its spectrum of activity was narrow. When tested on several gram-negative and gram-positive foodborne pathogenic bacteria such as Salmonella enterica, Salmonella enteritidis, Staphylococcus aureus, and Listeria monocytogenes, no antagonistic effect was observed. Applying the derivative from B. subtilis SC-8 within the same genus did not inhibit the growth of major soybean-fermenting bacteria such as Bacillus subtilis, Bacillus licheniformis, and Bacillus amyloquefaciens. The range of pH stability of the purified antagonistic substance was wide (from 4.0 to >10.0), and the substance was thermally stable up to 60 °C. In the various enzyme treatments, the antagonistic activity of the purified substance was reduced with proteinase K, protease, and lipase; its activity was partially destroyed with esterase. Spores of B. cereus did not grow at all in the presence of 5 μg/mL of the purified antagonistic substance. The isolated antagonistic substance was thought to be an antibiotic-like lipopeptidal compound and was tentatively named BSAP-254 because it absorbed to UV radiation at 254 nm.     

Diversity of culturable microorganisms and occurrence of Listeria monocytogenes and Salmonella spp. in Tuber aestivum and Tuber melanosporum ascocarps

The aim of this study was to investigate the total mesophilic microorganisms, Pseudomonas genus, Enterobacteriaceae family, mold and yeast counts and the presence of Listeria monocytogenes and Salmonella spp on Tuber aestivum and Tuber melanosporum ascocarps. The results confirmed that the major percentage of the microorganisms, approximately 9.0 log ufc/g, were present in the peridium, the glebas of healthy truffles being practically free of microorganisms. The predominant microbial group was the Pseudomonas averaging 8.3 and 8.4 log cfu/g on T. aestivum and T. melanosporum whole ascocarps, respectively. The Enterobacteriaceae also achieved high populations, especially in T. aestivum truffles, with 6.3 log cfu/g. Molds and yeasts never exceeded 5.0 log cfu/g. The characterization of the isolates revealed that the fluorescens pseudomonads were the most prevalent. Raoultella terrigena and Enterobacter intermedius were the dominant Enterobacteriaceae. The identification of the yeast isolates revealed five species: Debaryomyces hansenii, Issatchenkia scutulata, Rhodotorula aurantiaca, Saccharomyces dairensis and Trichosporon beigelii subspecies A and B. The mold genera detected in both species of truffles were Aspergillus, Cladosporium, Penicillium and Fusarium, Trichoderma being present only in T. aestivum. L. monocytogenes was found in 10% of the samples of T. aestivum analysed but Salmonella spp. was not detected. Knowledge of the microbial population in terms of possible food borne and pathogen microorganisms is very useful for establishing successful disinfection and storage methods to prolong the shelf-life of ascocarps of T. aestivum and T. melanosporum.     

Molecular characterization of Prototheca strains isolated from Italian dairy herds

One hundred sixty-one Prototheca spp. strains isolated from composite milk and barn-surrounding environmental samples (bedding, feces, drinking, or washing water, surface swabs) of 24 Italian dairy herds were characterized by genotype-specific PCR analysis. Overall, 97.2% of strains isolated from composite milk samples were characterized as Prototheca zopfii genotype 2, confirming its role as the main mastitis pathogen, whereas Prototheca blaschkeae was only sporadically isolated (2.8%). Regarding environmental sampling, 84.9% of isolates belonged to P. zopfii genotype 2, 13.2% to P. blaschkeae, and 1.9% to P. zopfii genotype 1. The data herein contradict previous hypotheses about the supposed exclusive role of P. zopfii genotype 2 as the causative agent of protothecal mastitis and, on the contrary, confirm the hypothesis that such pathology could be caused by P. blaschkeae in a few instances.     

Sequential extraction of polysaccharides from enzymatically hydrolyzed okara byproduct: Physicochemical properties and in vitro fermentability

Okara, a byproduct of soymilk production, has been upgraded through the use of an enzymatic treatment with Ultraflo L® to give a product (okara^ET) which has a higher content of soluble dietary fibre and an enhanced ratio of soluble: insoluble fibre than is found in okara without treatment. Polysaccharides were isolated from okara^ET by sequential extraction to yield soluble fractions in water (22%), CDTA (8.7%), alkali (37.7%) without and NaClO₂ (9.1%) and the cellulosic residue represents a (22.5%). The physicochemical properties of okara^ET were improved due to the enzymatic treatment: oil retention capacity (6.94 g/g), water retention capacity (10.76 g/g) and swelling capacity (13.85 g/g) were higher than in okara that had not undergone enzymatic treatment. The gelation capacity (8%) and the cation exchange capacity (8.96 mEq/kg) of okara^ET were lower than that of other byproducts. Short chain fatty acid production during in vitro fermentation of okara^ET by a pure culture of Bifidobacterium bifidus was mainly represented by acetic acid, followed by propionic and butyric acids. In addition, the decreases in pH and substrate consumption demonstrated the bifidogenic capacity of okara^ET.     

Inhibition of Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) development with essential oil extracted from Cymbopogon schoenanthus L. Spreng. (Poaceae), and the wasp Dinarmus basalis (Rondani) (Hymenoptera: Pteromalidae)

The control of the development of Callosobruchus maculatus was studied using a method that combined exposure to essential oil extracted from Cymbopogon schoenanthus and the introduction of a pteromalid natural enemy of the bruchid, Dinarmus basalis. The effect of the essential oil used was evaluated on all developmental stages of C. maculatus and on adults of D. basalis. At the highest concentration tested (33.3 μl/l) all adults of C. maculatus were killed within 24 h of exposure to the oil and the development of newly laid eggs and neonate larvae was also inhibited. However, the oil had variable efficacy against the bruchid instars developing inside the seeds: 5-day-old larvae (63% LI and 37% LII) of C. maculatus developing inside the seeds proving to be highly susceptible while 15-day-old insects (84% of pupae and 16% of larvae) were tolerant. Under the same conditions (33.3 μl/l), adults of D. basalis were very susceptible to oil vapours and to the residual activity of the oil after 3 or 6 days. However, the introduction of 10 pairs of adult D. basalis into a jar containing 100 hosts aged 10 days, 3 or 6 days before the oil application, gave respectively an emergence of 26 or 18 adults of the parasitoid compared to 28 in the control and there was no adult emergence of the host. The possibility of an integrated pest management strategy by using allelochemicals such as essential oils and indigenous natural enemies to control C. maculatus development in cowpea stocks is discussed.