Effect of incubation temperature on variations in bacterial communities grown in fermenting meju and the nutritional quality of soy sauce

The effect of meju fermentation temperature on bacterial diversity and soy sauce quality was evaluated. Meju was fermented at 30, 40, 50, and 60°C for 30 days and soy sauce was prepared using fermented meju. Bacteria grown in fermenting meju at 30 and 40°C were mesophiles but bacteria grown at 50 and 60°C were thermophiles. Most bacteria grown at 30 and 40°C were Bacillus and 2 were Clostridium. Bacteria grown at 50 and 60°C were Ureibacillus, Geobacillus, Anoxybacillus, and Bacillus. Free amino acids, total nitrogen, and organic acid contents in soy sauce increased, but the ammonium content decreased in proportion to the cultivation temperature. Most bacteria grown in meju fermented at 50 and 60°C and only a few grown at 30 and 40°C produced extracellular proteolytic enzymes. Few bacteria grown at 30 and 40°C, but all bacteria grown at 50 and 60°C, were probably responsible for meju fermentation.     

Molecular characteristics of partially hydrolyzed fucoidans from sporophyll of Undaria Pinnatifida and their in vitro anticancer activity

The effects of molecular characteristics on the anticancer activity of fucoidans were investigated after hydrolysis by copper acetate and then fractionation with 30 and 5 kDa membranes, which produced three fucoidan fractions: F_>30 K, F_5–30 K and F_<5 K. The F_>30 K and F_5–30 K consisted of mostly carbohydrate (58.2–61.3%) and sulphate (31.7–35.5%) with small amounts of proteins (1.2–6.4%). However, the major constituents of F_<5 K were sulphate (31.8%) and ash (37.5%) with smaller amounts of carbohydrate (15.5%) and protein (1.2%). The molecular weights (M_w) of F_>30 K, F_5–30 K and F_<5 K, obtained by a light scattering technique, were 262, 5.6 and 1.6 kDa, respectively. The observed anticancer activities were 18.0–28.5% for F_>30 K, 19.2–57.5% for F_5–30 K and 26.5–36.5% for F_<5 K, respectively, in the concentration range of 0.2–0.8 mg/mL. The results suggest that the anticancer activity of fucoidans could be considerably improved by lowering their M_w and by improving the binding properties of sulphate groups possibly through changing the molecular conformation.     

Behavior and incidence of Vibro parahaemolyticus in Sydney rock oysters (Crassostrea commercialis)

Vibrio parahaemolyticus grew poorly or not at all during storage of unopened Sydney rock oysters (Crassostrea commercialis) at 15 and 30°C for 2 and 7 days. Although V. parahaemolyticus counts often increased at 30°C, counts above 10⁴/g were not observed. Escherichia coli counts did not usually change substantially under these conditions. V. parahaemolyticus grew more readily during storage of unopened oysters under more severe conditions, with counts approaching or exceeding 10⁶/g after continuous or intermittent storage at 37°C. Opened oysters provided a much more favourable environment than unopened oysters for growth of V. parahaemolyticus. Growth occurred at 15, 30 and 37°C, with counts > 10⁶/g after overnight storage at 30 or 37°C. A survey of 30 market samples of oysters was conducted. Sixteen samples of unopened oysters were collected at the wholesale level and 14 samples of refrigerated opened oysters were purchased from retailers. V. parahaemolyticus was present in all samples of unopened oysters (range 0.4/g?2.3 × 10⁴/g) and in 13 samples of opened oysters (range 4.3/g? > 1.1 × 10³/g).     

The potential of Cycloclasticus and Altererythrobacter strains for use in bioremediation of petroleum-aromatic-contaminated tropical marine environments

Cycloclasticus sp. A5, which has been suggested to be a major degrader of petroleum aromatics spilled in temperate seas, showed higher degrading activities for petroleum aromatics, at both 25 °C and tropical sea temperature 30 °C, than the novel aromatic-degrading isolates, related to Altererythrobacter epoxidivorans (97.5% similarity in the almost full-length 16S rRNA gene sequence) and Rhodovulum iodosum (96.3% similarity), obtained after enrichment on crude oil in a continuous supply of Indonesian seawater. Cycloclasticus A5 degraded petroleum aromatics at a similar rate or faster at 30 °C as compared to 25 °C, but its growth on acetate was severely inhibited at 30 °C. These results suggest that, although their abundance would be low in tropical seas not contaminated with aromatics, the Cycloclasticus strains could be major degraders of petroleum aromatics spilled in tropical seas. The 16S rRNA gene of the Cycloclasticus strains has been identified from Indonesian seawater, and the gene fragments showed 96.7−96.8% similarities to that of Cycloclasticus A5. Introducing Cycloclasticus A5 may be an ecologically advantageous bioremediation strategy for petroleum-aromatic-contaminated tropical seas because strain A5 would disappear at 30 °C after complete consumption of the aromatics. Altererythrobacter and Rhodovulum-related isolates grew well on pyruvate in 10% strength marine broth at 30 °C whereas Cycloclasticus A5 did not grow well on acetate in the broth at 30 °C. These growth results, along with its petroleum-aromatic-degrading activity, suggest that the Altererythrobacter isolate could be an important petroleum-aromatic degrader in and around nutrient-rich tropical marine environments.     

Interactive effects of temperature and relative humidity on oviposition and development of Callosobruchus chinensis (L.) on azuki bean

The effects of three temperatures, 20 °C, 25 °C and 30 °C, and four relative humidity (RH) levels, 30–35%, 50–55%, 70–75%, and 90–95%, on oviposition and development of Callosobruchus chinensis (L.) (Coleoptera: Bruchidae) were investigated. C. chinensis were introduced to 30 g azuki bean seeds (cultivar Hongeon) one day post emergence. Five pairs of male and female beetles were used for each combination of temperature and RH, and replicated ten times. The introduced adults were allowed to lay eggs for 72 h. Temperature significantly influenced oviposition with increased number of eggs at 30 °C. Relative humidity had no effect on egg laying. Development time was affected by both temperature and RH. Development time was shortest at 30 °C and 70–75% RH. Adult emergence rate was affected by both temperature and RH; adult emergence rate increased with the increase in temperature and RH (up to 70–75%) levels. The results suggest that rather than the interactive effect of temperature and RH, individual effects of temperature and RH on C. chinensis are profound and C. chinensis is likely to cause greater damage to azuki bean seeds stored at 30 °C and 70–75% RH.     

Temperature-dependent functional response and host preference of Habrobracon hebetor between fungus-infected and uninfected Ephestia kuehniella larvae

An ongoing question in biological control consists of whether antagonistic interaction between different agents can be reduced in pest biocontrol. This study investigated the behavioral performance of Habrobracon hebetor Say on Ephestia kuehniella Zeller larvae treated with Metarhizium anisopliae (Metsch.) Sorokin sensu lato (s.l.) (isolate M14) at two different temperatures (25 and 30 °C). A type II functional response was observed in female wasps of all treatments. Estimated handling time and attack rate values were not statistically different at two thermal conditions. Female wasps avoided the odor of fungus-infected host larvae when offered simultaneously with healthy ones at 30 °C revealed by olfactory choice test. The number of untreated larvae parasitized by H. hebetor females was significantly differed between temperatures (25 and 30 °C). Overall, this study suggests that application of M. anisopliae s.l. for biological control of E. kuehniella is compatible with concurrent use of H. hebetor at 30 °C.     

The protective effect of chlorogenic acid on bovine mammary epithelial cells and neutrophil function

Chlorogenic acid (CGA) is the ester of caffeic acid and quinic acid and plays an important role in antibacterial activity and anti-inflammatory properties. The objective of this study was to examine the effects of CGA on the growth of Staphylococcus aureus and the mRNA levels of the genes encoding the inflammatory response cytokines, κ-casein, and neutrophil function in bovine mammary epithelial cells (BMEC) exposed to S. aureus. Chlorogenic acid has important antibacterial, antioxidant, and anti-inflammatory functions; however, the effect of CGA on BMEC and neutrophils exposed to S. aureus has not been investigated previously. Our results demonstrated that 10, 20, and 30 μg/mL CGA had no cytotoxic effects on BMEC in culture, and that 20 μg/mL CGA enhanced the viability of BMEC exposed to S. aureus, whereas 30 μg/mL CGA reduced S. aureus growth after 9 h compared with controls. The rate of S. aureus invasion into BMEC was also attenuated by 30 μg/mL CGA compared with controls, whereas this treatment led to reduced abundance of IL6, IL8, and TLR2 mRNA in S. aureus-exposed BMEC. Migration of bovine polymorphonuclear leukocytes was significantly decreased in S. aureus-exposed BMEC with 10 and 20 μg/mL CGA treatment when compared with S. aureus treatment alone. In addition, incubation with 20 or 30 μg/mL CGA enhanced the phagocytic ability of polymorphonuclear leukocytes compared with the control group. Importantly, levels of κ-casein were enhanced by treatment of S. aureus-exposed BMEC with CGA. Our results suggest that the use of CGA may be a potent therapeutic tool against bovine mastitis caused by S. aureus.     

Probability of growth and toxin production by nonproteolytic Clostridium botulinum in rockfish fillets stored under modified atmospheres

Whether toxin production by Clostridium botulinum precedes or follows spoilage of fish stored under modified atmospheres (MA), remains unclear. In this factorial design study we inoculated a pool of nonproteolytic C. botulinum spores (5 type E, 4 type B, and 4 type F strains) at 6 levels (10⁴ to 10⁻¹) between two rockfish fillets and then incubated the fillets at 4, 8, 12 and 30°C under vacuum, 100% CO₂ and 70% CO₂+30% air for 21 days. The probability of toxigenesis by one spore was significantly affected (P<0.005) by temperature (T) and storage time (S_t), and not (P>0.1) by MA, MA×T or MA×S_t. At the 10° spore/sample level, the earliest time to detect toxin production at 4,8,12 and 30°C under all MAs was >21, 15–21, 6–9 and 2 days, respectively. No toxin production was detected at 4°C. Only type B toxin was present in the toxic samples. At 30°C storage, spoilage of fillets followed toxigenesis. Using linear and logistic regression models, equations were derived that could estimate the lag phase and predict the probability of one spore initiating growth under a particular storage condition.     

Influence of pH,water activity and temperature on the inactivation of Escherichia coli and Saccharomyces cerevisiae by pulsed electric fields

The aim of this study was to examine the influence of pH, water activity (a_w) and temperature on the killing effect of pulsed electric fields (PEF). Escherichia coli and Saccharomyces cerevisiae suspended in a model media were subjected to 20 pulses with 4 μs duration in a continuous PEF system, during which the effects of pH (4.0–7.0), a_w (1.00–0.94) and inlet temperature (10°C and 30°C) could easily be studied. Electrical field strengths were set to 25 kV/cm for S. cerevisiae and 30 kV/cm for E. coli and the highest outlet temperature was monitored to 44°C. A synergy of low pH values, high temperatures and PEF processing was observed. A drop in pH value from 7.0 to 4.0 resulted in the reduction of E. coli by four additional log units, whereas for S. cerevisiae, the pH effect was less pronounced. Lowering a_w seems to protect both E. coli and S. cerevisiae from PEF processing.     

Physiological and Pathological Factors Influencing Bovine Immunoglobulin G2 Concentration in Milk

Bovine IgG₂ concentration was determined by radial immunodiffusion in 355 milk samples of uninfected quarters, 101 milk samples of infected quarters, and 118 blood serum samples from 42 Holstein-Friesian cows taken at 30, 150, and 270 d. Concentration of IgG₂ in blood serum (11.3 mg/ml) was highest at the beginning of lactation (30 d). Immunoglobulin G₂ concentration in milk (16.81 μg/ml) from cows with uninfected quarters was not affected by quarter location but was correlated with IgG₂ concentration in blood serum (.30; P<.001). The IgG₂ concentration in milk was lower in midlactation (150 d: 14.81 μg/ml) and in the two first lactations. Immunoglobulin G₂ concentration in milk was correlated with SCC.Quarter infection by Corynebacteriutn bovis or major pathogens increased IgG₂ concentration up to 47.9 μg/ml for Staphylococcus aureus. Only S. aureus influenced IgG₂ concentration in blood serum. Correlation between IgG₂ content and SCC in milk decreased when quarters were infected, regardless of bacterial species.     

The effect of temperature and humidity upon the development and fecundity of Dermestes haemorrhoidalis Küster and Dermestes peruvianus Laporte de Castelnau (Coleoptera: Dermestidae)

Larvae of Dermestes haemorrhoidalis Küster and D. peruvianus Cast. were bred on a diet of fishmeal, wheat-germ, yeast and cholesterol at 15, 20, 25, 30 or 32.5°C with a constant 65% r.h. and at 25°C with 40, 50, 60, 70 or 80% r.h. Whenever possible emerging adults were paired and kept under the same conditions to determine their longevity and fecundity. Egg hatch was determined at a wider range of temperatures and humidities. Eggs of D. peruvianus hatched over the range 10–30°C and those of D. haemorrhoidalis from 12.5–35°C when the eggs were laid at 25°C. D. haemorrhoidalis completed development from 20 to 32.5°C, the period ranging from about 100 days (20°C) to about 38 days (30°C). D. peruvianus developed from 15 to 30°C taking about 300 days (15°C) to about 60 days (25°C, 80% r.h.). Both species developed at all humidities tested at 25°C. Adult D. haemorrhoidalis lived up to 240 days if provided with a weekly drink and the longest lived D. peruvianus exceeded 300 days. Adult D. haemorrhoidalis bred at 30°C laid few eggs and those bred at over 30°C were infertile. At 20 and 25°C approximately 150 eggs were found over a period of up to 220 days, most eggs being deposited in the first 100 days. Few eggs of D. peruvianus were found except at 20°C and to a lesser extent at 25°C, 80% r.h. At 20°C, the number of eggs found averaged 75 laid over up to 300 days, the rate of oviposition diminishing with age of female. It is suggested that egg-cannibalism is a probable cause of the apparent low productivity of D. peruvianus females.     

The influence of temperature on the adhesion of mixed cultures of Staphylococcus aureus and Escherichia coli to polypropylene

The adhesion of Staphylococcus aureus and Escherichia coli, in mixed cultures, to polypropylene surfaces was evaluated at 12°C and 30°C. The micro-organisms were isolated from a chicken carcass and cultured in an aqueous extract, prepared from the same carcass, for the production of biofilms on polypropylene coupons. Adhered cells were counted by epifluorescence microscopy with acridine orange staining. Escherichia coli adhered in greater numbers to the coupons than S. aureus at both temperatures. Staphylococcus aureus adhered better at 12°C than at 30°C, while the reverse was true for E. coli. At 30°C, there was no increase in the number of adherent cells ofS. aureus over 8 h, while E. coli increased from a median of 5·0–19·0 per microscope field. At 12°C, the major increase in adherent cell numbers for both species occurred between 2 and 4 h, so that leaving cleaning until 8 h, as is common, would not result in greatly increased biofilms, 2-hourly cleansing is clearly unrealistic. However, total adherent cell numbers were the same at 12° and 30°C between 4 and 6 h incubation. Hence it seems that reduced temperature has little to offer for restricting biofilm formation on polypropylene work surfaces in a well-run food processing plant.     

Contributions to selected phenotypic characteristics of large species- and lineage-specific genomic regions in Listeria monocytogenes

We hypothesized that genomic regions specific to Listeria monocytogenes or selected L. monocytogenes strains may contribute to virulence and phenotypic differences among the strains. A whole genome alignment of two completed L. monocytogenes genomes and the one completed Listeria innocua genome initially identified 28 genomic regions of difference (RD) > 4 kb that were found in one or both L. monocytogenes genomes, but absent from the non-pathogenic L. innocua. In silico analyses using an additional 18 draft L. monocytogenes genomes showed that (i) 15 RDs were found in all or most L. monocytogenes genomes; (ii) three RDs were found in all or most lineage I genomes, but absent from lineage II genomes; and (iii) four RDs were found in all lineage II genomes, but no lineage I genomes. Null mutants in two L. monocytogenes-specific RDs (RD16 and RD30; found in most L. monocytogenes) and the lineage II-specific RD25 showed no evidence for impaired invasion or intracellular growth in selected tissue culture cells. Although, in pH 5.5 minimal media, the ΔRD30 null mutant showed reduced ability to compete with its parent strain, indicating that RD30 may have a role in L. monocytogenes growth under limited nutrient conditions at acidic pH.     

Probiotic in lamb rennet paste enhances rennet lipolytic activity, and conjugated linoleic acid and linoleic acid content in Pecorino cheese

Cheeses manufactured using traditional lamb rennet paste, lamb rennet paste containing Lactobacillus acidophilus, and lamb rennet paste containing a mix of Bifidobacterium lactis and Bifidobacterium longum were characterized for the lipolytic pattern during ripening. Lipase activity of lamb rennet paste, lamb rennet containing Lb. acidophilus, and lamb rennet containing a mix of bifidobacteria was measured in sheep milk cream substrate. Rennet paste containing probiotics showed a lipase activity 2-fold greater than that displayed by traditional rennet. Total free fatty acid (FFA) in sheep milk cream was lower in lamb rennet paste (981 μg/g of milk cream) than in lamb rennet containing Lb. acidophilus (1,382.4 μg/g of milk cream) and in lamb rennet containing a mix of bifidobacteria (1,227.5 μg/g of milk cream) according to lipase activity of lamb rennet paste. The major increase of FFA in all cheeses occurred during the first 30 d of ripening with the greatest values being observed for C16:0, C18:0 C18:1. At 60 d of ripening all cheeses showed a reduction in the amount of free fatty acids; in particular, total free fatty acids underwent a decrease of more than 30% from 30 to 60 d in cheeses manufactured using traditional lamb rennet paste, whereas the same parameter decreased 10% in cheeses manufactured using lamb rennet paste containing Lb. acidophilus and cheeses manufactured using lamb rennet paste containing a mix of B. lactis and B. longum. Cheese containing Lb. acidophilus was characterized by the greatest levels of total conjugated linoleic acids (CLA) 9-cis, 11-trans CLA and 9-trans, 11-trans CLA, whereas cheese containing bifidobacteria displayed the greatest levels of free linoleic acid. Rennet pastes containing viable cells of Lb. acidophilus and a mix of B. lactis and B. longum were able to influence the amount of FFA and CLA in Pecorino cheese during ripening.     

Quality and antioxidant property of green tea sponge cake

Green tea powder was used to substitute 0%, 10%, 20%, and 30% of wheat flour to make sponge cakes, called the control, GT10, GT20, and GT30, respectively. The viscosity and specific gravity in cake batter, and hardness, gumminess, chewiness, crumb a value, protein, total dietary fibre, ash, and various catechin content of baked cakes increased with increasing green tea levels whereas the volume, cohesiveness, adhesiveness, springiness, resilience, crust L, a, b and crumb L, b values of samples showed a reverse trend. No differences were found in all hedonic sensory results for control, GT10, and GT20 whereas GT30 were rated lower in all sensory results. Green tea cake contained a greater variety of catechins, and had good antioxidant activity, reducing power, scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radicals and chelating ability on ferrous ions. Overall, green tea cake could be developed as a food with more effective antioxidant properties.     

Growth Kinetics Parameters of Salmonella spp. in the Peel and in the Pulp of Custard Apple (Annona Squamosa)

The growth kinetic parameters (maximum growth rate, μ; lag time, λ and maximum population, k) of Salmonella spp. on the peel and in the pulp custard apple at 10, 15, 20 and 30°C were determinated. Samples of peel and pulp of custard apple were inoculated with a cocktail of three strains of Salmonella spp. (S. Typhimurium, S. Enteretidis and S. Montevideo) and further stored at 10, 15, 20 and 30°C. Salmonella can survive and multiply in both, the peel and in the pulp of the custard apple. Lower temperatures retard, but do not prevent Salmonella growth.     

Steady and dynamic oscillatory shear rheological properties of ketchup-processed cheese mixtures: Effect of temperature and concentration

The steady and dynamic shear properties of ketchup-processed cheese (K-PC) mixtures were investigated at different temperatures (10-50 °C) and PC concentrations (0-30%). The K-PC mixtures showed a shear-thinning behavior with low magnitudes of yield stress. The consistency coefficient (K) and apparent viscosity (η₅₀) decreased with increase in temperature and concentration. The mixtures followed the Arrhenius temperature relationship, indicating that the magnitudes of activation energies (E_a) were in the range of 8.83-17.16 kJ mol⁻¹. Storage (G′), loss (G′′) and complex (G∗) modulus increased with increase in frequency while complex viscosity (η∗) decreased. The K-PC mixtures at concentrations of 0-15% exhibited weak gel-like behavior. Increase in the PC concentration resulted in a decrease in G∗, G′, G′′ and η∗ up to the 15% of PC concentration, showing a plateau value between 0% and 30% concentrations. Cox-Merz rule was not applicable to K-PC mixtures.     

Characterization of cottage cheese using Weissella cibaria D30: Physicochemical,antioxidant, and antilisterial properties

This study aimed to evaluate the potential of Weissella cibaria D30 as an adjunct culture in cottage cheese, including an assessment of antioxidant, antilisterial, and compositional parameters. Cottage cheese samples were manufactured using a commercial starter culture and probiotic strains Lactobacillus rhamnosus GG (GG) or W. cibaria D30 (W) and without probiotic (control). Samples were stored at 4 ± 1°C for 28 d. Bacterial cell counts (log cfu/g) of control, GG, and W samples were counted at 0, 7, 14, 21, and 28 d. Counts of W. cibaria D30 in the W samples remained at 6.85 log cfu/g after 28 d. Total solids, fat, protein, ash, and pH were measured and no significant differences were observed in compositional parameters or pH after 28 d of storage in all cheeses except those inoculated to Listeria monocytogenes. To measure the antilisterial effect, Listeria monocytogenes was inoculated into the cottage cheese samples and bacterial cell counts were obtained at 0, 6, 12, 24, 48, 72, 96, 120, and 144 h. Listeria monocytogenes counts were less than the analytical limit of detection (<10 cfu/g) in the inoculated GG and W samples, whereas the counts of L. monocytogenes in the inoculated control sample remained at 3.0 log cfu/g after 144 h. We used the DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS [2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] radical scavenging activity assays to assess antioxidant activity: GG and W samples exhibited significant increases in antioxidant activity compared with the control sample. These results indicate that W. cibaria D30 has potential as an adjunct culture in the dairy industry.     

Distance and height of attraction by walking and flying beetles to traps with simultaneous use of the aggregation pheromones from Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae)

Adults of Tribolium castaneum (Herbst) and Rhyzopertha dominica (F.) biosynthesize aggregation pheromones 4,8-dimethyldecanal and dominicalure-1/dominicalure-2, respectively. These pheromones are commonly used independently, and their simultaneous use has not been adequately studied. Furthermore, information on trapping flying R. dominica in pheromone traps is minimum. Therefore, the objectives were to evaluate distance of attraction of T. castaneum and R. dominica adults to traps having both pheromones, and height of R. dominica adult attraction to traps with its pheromone lure alone. In first experiment, both pheromones were deployed simultaneously inside a commercial pitfall trap. One-month-old 20 T. castaneum and R. dominica adults were released every 30 cm from the pheromone trap. The adults trapped were recorded at 4 and 24 h following their release. Adults of both species released were captured in higher percentages at 24 h than 4 h. At 30 cm distance, these values were 45.5% for T. castaneum and 10–12% for R. dominica for 24 h whereas they were 40.5% for T. castaneum and 5–7.5% for R. dominica following 4 h exposure. The maximum trap capture was at 30 cm for T. castaneum and 30–60 cm for R. dominica. In second experiment, a trap with two rubber septa containing dominicalure-1 and dominicalure-2 was placed at different heights inside cage, and R. dominica adults were released at the bottom. In each experiment, four replicates were tested. After 24 h, flying R. dominica adults were captured in progressively lower percentages as trap height increased up to 40 cm above the bottom of cage. Trap heights above 10 cm exhibited decreased trap capture of R. dominica compared to those at 3 cm. We conclude that simultaneous use of both aggregation pheromones better facilitates trapping of walking T. castaneum and R. dominica. Traps above 10 cm show decreased captures of flying R. dominica.