Insect chitosan as a natural antimicrobial against vegetative cells of Bacillus cereus in a cooked rice matrix.

This study investigates the antimicrobial activity of insect chitosan against vegetative cells of Bacillus cereus in a rice matrix. Sample culture solutions were prepared with different concentrations of insect chitosan (150, 180, 220 and 250 µg/mL) and tested at three temperatures (30 °C, 20 °C and 10 °C), which simulate different storage temperature scenarios of precooked rice. The results indicate that insect chitosan has antimicrobial activity that depends on temperature and chitosan concentration. For the assays with chitosan at 10 °C, all concentrations were bactericidal during the study time, reaching a maximum inactivation of 6 log cycles for 250 µg/mL. At 20 °C and at 30 °C a bacteriostatic activity was observed for concentrations of 150 µg/mL and 180 µg/mL. Results also showed that concentrations of 220 µg/mL and 250 µg/mL were bactericidal for all the temperatures tested during the storage time. When rice is cooked and not stored at an appropriate temperature, below 10 °C, the consumer's health is at risk. In these cases, insect chitosan could be a good additional control measure to control B. cereus growth and toxin formation in cooked rice.

Effect of the addition of liquid whey from cheese making factory on the physicochemical properties of whey protein isolate gels made by high hydrostatic pressure.

The objective of the present work was to study the effect of liquid whey from the cheese production process on the gels developed by high hydrostatic pressure from whey protein isolate powder (WPI). Changes in pH, color, textural parameters, and water retention capacity of the gels obtained were analyzed during storage for 28 days at refrigeration temperature (4 °C). Mixtures of liquid whey from cheese making processes and different WPI percentages gave gels with different characteristics after being processed by high hydrostatic pressures. The pH values and color parameters (L*, a*, b*) varied slightly, depending directly on WPI concentration and storage time. The values of hardness, elasticity, and cohesiveness were dependent on the liquid medium used to dissolve the WPI (liquid cheese whey or distilled water), WPI concentration, and storage time. The use of liquid cheese whey for gel formation favored water retention, reducing the appearance of syneresis (exudation). The results obtained in the present study indicated a possible use and revalorization of cheese whey obtained in cheese production to obtain WPI gels with improved physicochemical properties, using high hydrostatic pressure as technology for their production.

Effect of sample time on urinary lithogenic risk indexes in healthy and stone-forming adults and children.

BACKGROUND: The diagnosis and follow-up of stone forming patients is usually performed by analysis of 24-h urine samples. However, crystallization risk varies throughout the day, being higher at night. The main objective of this study is to evaluate the urinary crystallization risk in adults and children by calculating risk indexes based on different collection periods. METHODS: The study included 149 adults (82 healthy and 67 stone-formers) and 108 children (87 healthy and 21 stone-formers). 24-h urine was collected, divided into 12-h daytime sample (8 am to 8 pm), and 12-h overnight sample (8 pm to 8 am next morning). Solute concentrations, the calcium to citrate ratio (Ca/Cit), and the ion activity product of calcium oxalate (AP[CaOx]) and calcium phosphate (AP[CaP]) were calculated in each 12-h sample and in overall 24-h urine. Assessments were also related to stone type. RESULTS: Ca/Cit and AP(CaOx) were significantly higher in stone forming patients than in healthy subjects. The 12-h overnight samples had the highest values for both risk indexes, confirming a greater risk for crystallization at night. The AP(CaP) index was significantly higher in patients with pure hydroxyapatite stones than healthy controls, but was not significantly different between stone-formers overall and healthy controls. CONCLUSIONS: The calculation of risk indexes is a simple method that clinicians can use to estimate crystallization risk. For this purpose, the use of 12-h overnight urine may be a reliable alternative to 24-h collections.

Antimicrobial potential of cauliflower, broccoli, and okara byproducts against foodborne bacteria.

The antimicrobial potential of cauliflower, broccoli, and okara byproducts was assessed against Gram-positive and Gram-negative bacteria. Salmonella enterica serovar Typhimurium, Escherichia coli O157:H7, Bacillus cereus, and Listeria monocytogenes serovar 4b growth behavior was assessed under exposure to 5% vegetable byproducts added to the reference medium, buffered peptone water (0.1% [wt/vol]), at 37°C. Although the byproducts were not effective against L. monocytogenes, they were bactericidal against Salmonella Typhimurium, E. coli O157:H7, and B. cereus. The most promising results were achieved with the cauliflower-Salmonella Typhimurium combination, because the bacterial population was reduced by 3.11 log10 cycles after 10 h of incubation at 37°C as a result of 5% cauliflower addition. Further studies were carried out for this combination, at different cauliflower concentrations (0, 0.5, 1, 5, 10, and 15%) and at temperatures in the range of 5-37°C. The greatest inactivation level (6.11 log10 cycles) was achieved at refrigeration temperature (5°C) using 15% cauliflower addition. Both temperature and cauliflower concentration significantly (p≤0.05) influenced the Salmonella Typhimurium inactivation level. The kinetic parameters were adjusted to mathematical models. The modified Gompertz mathematical model provided an accurate fit (root-mean-square error (RMSE) [0.00009-0.21] and adjusted-R(2) [0.81-0.99]) to experimental Salmonella Typhimurium survival curves describing inactivation kinetics of the pathogen to the antimicrobial effect of cauliflower byproduct.

Urinary excretion of calcium, magnesium, phosphate, citrate, oxalate, and uric acid by healthy schoolchildren using a 12-h collection protocol.

BACKGROUND: Improving knowledge about normal urine composition in children is important for early prevention of lithiasis. We describe urinary excretion values of calcium (Ca), magnesium (Mg), phosphate (P), citrate (Cit), uric acid (Ur), and oxalate (Ox) in healthy children with and without a family history of lithiasis, using a 12-h urine collection protocol. METHODS: Urine samples were obtained from 184 children (5-12 years): a spot sample collected in the afternoon, and a 12-h overnight sample. Solute/creatinine (Cr) and 12-h solute excretion was calculated. RESULTS: Urinary excretion values of the studied solutes are presented as percentile values, separately for each type of sample. Due to age-related differences in the solute/creatinine ratios, except for Ca and Cit, results are described according to the child's age. The presence of excretion values related to an increased risk of lithiasis was more common in children with a family history. CONCLUSIONS: We report data from urine samples collected by using a simplified collection protocol. The observed differences between children with and without a family history of lithiasis could justify that in population studies aimed at setting reference values, the former are excluded.

Use of the modified Gompertz equation to assess the Stevia rebaudiana Bertoni antilisterial kinetics.

In order to assess the antibacterial activity of Stevia rebaudiana Bertoni (Stevia), Listeria innocua growth was characterized at 37 °C, in reference medium supplemented with a leaf infusion, a crude extract, and a steviol glycosides purified extract. Experimental data were fitted to the modified Gompertz model and the antibacterial activity of Stevia was determined based on the lag time (λ) and the maximum growth rate (µmax) reached, depending on the incubation conditions. As the leaf infusion showed the most marked elongation of λ and the most marked µmax reduction, its antimicrobial effect was evaluated at different concentrations, at 37, 22 and 10 °C. According to the results obtained, in general, the lower the temperature or the higher the Stevia concentration, the longer the λ and the lower the µmax, statistically significant being the effect of reducing temperature from 37 or 22 to 10 °C, the effect of increasing Stevia concentration from 0 or 0.5 to 1.5 or 2.5% (w/v), at 37 °C, and the elongation of λ observed in presence of 1.5 and 2.5% (w/v) of Stevia, at 22 °C. These results show that Stevia could be a bacterial growth control measure if a cold chain failure occurs.

Urinary phytate (Myo-inositol hexaphosphate) in healthy school children and risk of nephrolithiasis.

OBJECTIVE: Although the incidence of urolithiasis is lower in children than in adults, the number of children with urolithiasis is increasing. Phytate, a naturally occurring compound present in legumes, nuts, and whole meals, has antilithiasic activity. The aim of this study was to assess, for the first time, the urinary levels of phytate in children and to correlate these levels with other urinary parameters related to crystallization risk and to general dietary habits. DESIGN AND METHODS: This was a cohort study conducted from April 2012 to March 2013 in the Laboratory of Investigation in Renal Lithiasis and at Son Espases Universitary Hospital in Palma de Majorca, Spain. SUBJECTS: Subjects included 165 healthy schoolchildren aged 5 to 12 years. INTERVENTION: All subjects followed their habitual diet. Information on the main dietary habits of the study subjects was obtained by asking each child's parents to fill out a dietary questionnaire. MAIN OUTCOME MEASURE: Phytate and citrate concentration and excretion were measured in 2 urine samples (a spot sample and a 12-hour overnight sample) for each child. Furthermore, common urinary biochemical indicators of stone risk were measured in each sample. RESULTS: The urinary phytate concentrations were low in this child population because of low consumption of dietary phytate. The urinary concentrations of phytate and citrate were low in 27.5% of these children. CONCLUSION: Because both substances are important inhibitors of crystallization, these finding suggests that these children are at risk of crystallization. Moreover, their diets consisted of foods rich in animal protein, with insufficient consumption of vegetables, legumes, and fruits.

Risk factors for urinary stones in healthy schoolchildren with and without a family history of nephrolithiasis.

BACKGROUND: The prevalence of lithiasis is increasing at all ages. This study aimed to assess the crystallization risk in urine from healthy school children and to determine urinary parameters that are most associated with it. METHODS: Urine samples were obtained from 184 children aged 5-12 years: a spot sample collected in the afternoon, and a 12-h overnight sample. Information was obtained regarding family histories of lithiasis. Urine volume, pH, and biochemical parameters of stone risk were measured. Crystallization risk was defined by the presence of specific urine conditions that had previously been associated with stone formation in vitro. RESULTS: Crystallization risk was observed in 15 % of spot urine samples and 54 % of 12-h samples. Metabolic abnormalities and a low urinary volume were more frequently detected in children with crystallization risk. Calcium excretion and calcium/citrate ratio were higher in children with a family history of lithiasis. CONCLUSIONS: We observed a high prevalence of crystallization risk in urine, especially in children with a family history of the disease. Low urinary volume was the factor most associated with increased risk. Adequate fluid intake at an early age may be a simple and effective measure to reduce the incidence of nephrolithiasis.

Antimicrobial potential of flavoring ingredients against Bacillus cereus in a milk-based beverage.

Natural ingredients--cinnamon, cocoa, vanilla, and anise--were assessed based on Bacillus cereus vegetative cell growth inhibition in a mixed liquid whole egg and skim milk beverage (LWE-SM), under different conditions: ingredient concentration (1, 2.5, and 5% [wt/vol]) and incubation temperature (5, 10, and 22 °C). According to the results obtained, ingredients significantly (p<0.05) reduced bacterial growth when supplementing the LWE-SM beverage. B. cereus behavior was mathematically described for each substrate by means of a modified Gompertz equation. Kinetic parameters, lag time, and maximum specific growth rate were obtained. Cinnamon was the most bacteriostatic ingredient and cocoa the most bactericidal one when they were added at 5% (wt/vol) and beverages were incubated at 5 °C. The bactericidal effect of cocoa 5% (wt/vol) reduced final B. cereus log10 counts (log Nf, log10 (colony-forming units/mL)) by 4.10 ± 0.21 log10 cycles at 5 °C.

Joint effect of heat, pH and grape extract on Bacillus cereus spores survival in a rice solution.

Rice due to its high carbohydrate content, is an ideal medium for Bacillus cereus growth, a spore-producing microorganism. The objective of this study was to determine the antimicrobial activity of a grape extract in combination with heat treatments and different pH against B. cereus spores in a rice solution. The survivor data obtained were fitted to the Weibull survival function, and the values of parameters a and b (scale and shape indexes, respectively) were determined. Results showed that the grape extract affected the survival of B. cereus spores at 90 °C and 95 °C, reaching greater logarithmic reductions in acidic pH values. This behaviour was reflected in a parameter of the Weibull survival function which decreased as the temperature increased and at acidic pH values. In addition, a secondary model was developed by relating the logarithm of a to the independent variables (temperature and pH). A global model relating B. cereus inactivation with temperature and pH was developed, and validated by calculating the accuracy factor. The results demonstrate the usefulness of grape extract as a by-product, which can be used as an additional control measure for rice, especially when combined with mild heat treatments and acidic pH values.

Joint effect of temperature and insect chitosan on the heat resistance of Bacillus cereus spores in rice derivatives.

The heat resistance of Bacillus cereus spores inoculated in a rice substrate supplemented with insect chitosan as an alternative antimicrobial was studied. Two concentrations of insect chitosan were considered in order to assess the role of the insect chitosan concentration during the heat process. Results of the study indicated that the DT values were higher in the substrate without chitosan than in the substrate containing chitosan thus indicating a greater heat resistance to heat treatment of the microorganism inoculated in the substrate without chitosan. This behaviour was also evidenced in the survival curves. There were no great differences between either of the insect chitosan concentrations tested regarding the DT values. The z values were 9.8°C on rice substrate and8.9°C on rice substrate supplemented with insect chitosan at 150 µg/mL and 10.7°C on rice substrate supplemented with 250 µg/mL of insect chitosan. The chitosan concentration appears to affect the z value of the microorganism. Our results indicate that the combination of heat with insect chitosan as an antimicrobial on foodstuffs subjected to cooking is feasible and can improve the safety of rice derivatives.

Inactivation of human and murine norovirus by high-pressure processing.

The effect of high hydrostatic pressure (HPP) was evaluated for inactivation of murine norovirus (MNV), a propagable norovirus (NoV), and human NoV genogroup II.4. Inactivation of MNV was assessed by viral culturing (50% tissue culture infectious dose [TCID(50)]) and real-time reverse-transcription-polymerase chain reaction (RT-qPCR), whereas NoV survival was determined only by RT-qPCR. A treatment of 450 MPa for 15 min at 45°C was sufficient to inactivate 6.5 log(10) of infectious MNV in culture medium as determined by TCID(50). Further, the inactivation of MNV was enhanced when pressure was applied at an initial temperature of 25°C. On the other hand, a baroprotective effect was observed when MNV suspensions were supplemented with 10 mM of CaCl(2). A 400 MPa treatment at 45°C inactivated >5 log(10) of infectious MNV, whereas the addition of CaCl(2) increased the pressure resistance of MNV, with <0.5 log(10) reduction observed. MNV decay as determined by TCID(50) was generally greater than that determined by RT-qPCR; for instance, MNV genomes were detected even after 15 min treatment at 450 MPa, with <0.5 log(10) reduction. Experiments with NoV suspensions showed that all tested HPP treatments reduced the numbers of NoV by <0.5 log(10) units as determined by RT-qPCR. Additionally, RNA of human NoV was more resistant to certain HPP treatments than the RNA of MNV.

Effect of olive powder and high hydrostatic pressure on the inactivation of Bacillus cereus spores in a reference medium.

The aim of this work was to study the effect of olive powder combined with high hydrostatic pressure (HHP) on the inactivation of Bacillus cereus spores, to use it as an additional control hurdle in beverages pasteurised by this technology. With this purpose, reference medium prepared at different concentrations of olive powder was inoculated with B. cereus spores and subjected to different pressure treatments. The outgrowth capacity of the treated spores was then determined at 20°C and 32°C. The addition of olive powder was found to slightly reduce the effectiveness of HHP, although in post-treatment storage there was an increased bacteriostatic effect in the samples with 2.5% of olive powder at both temperatures in the samples pressurised at 400 and 500 MPa, and only at 20°C in the samples pressurised at 200 MPa. The addition of olive powder therefore had an additive effect with storage temperature and HHP processing and could act as an additional control hurdle during the shelf-life of products pasteurised by HHP technologies or in the case of cold-chain breakage.

Applications of Natural Antimicrobials in Food Packaging and Preservation.

In the food science field, the term "antimicrobial" basically refers to active substances of synthetic or natural origin, that are directly or indirectly present in a specific food, packaging material or food contact surface that affect the viability or the growth of microorganisms in that matrix [...].

Risk of Bacillus cereus in Relation to Rice and Derivatives.

Rice is a very popular food throughout the world and the basis of the diet of the citizens of many countries. It is used as a raw material for the preparation of many complex dishes in which different ingredients are involved. Rice, as a consequence of their cultivation, harvesting, and handling, is often contaminated with spores of Bacillus cereus, a ubiquitous microorganism found mainly in the soil. B. cereus can multiply under temperature conditions as low as 4 °C in foods that contain rice and have been cooked or subjected to treatments that do not produce commercial sterility. B. cereus produces diarrhoeal or emetic foodborne toxin when the consumer eats food in which a sufficient number of cells have grown. These circumstances mean that every year many outbreaks of intoxication or intestinal problems related to this microorganism are reported. This work is a review from the perspective of risk assessment of the risk posed by B. cereus to the health of consumers and of some control measures that can be used to mitigate such a risk.

Surface Micro Discharge-Cold Atmospheric Pressure Plasma Processing of Common House Cricket Acheta domesticus Powder: Antimicrobial Potential and Lipid-Quality Preservation.

The growing world population and the need to reduce the environmental impact of food production drive the exploration of novel protein sources. Insects are being cultivated, harvested, and processed to be applied in animal and human nutrition. The inherent microbial contamination of insect matrices requires risk management and decontamination strategies. Thermal sterilization results in unfavorable cooking effects and oxidation of fatty acids. The present study demonstrates the risk management in Acheta domesticus (home cricket) powder with a low-energy (8.7-22.0 mW/cm2, 5 min) semi-direct surface micro discharge (SMD)-cold atmospheric pressure plasma (CAPP). At a plasma power density lower than 22 mW/cm2, no degradation of triglycerides (TG) or increased free fatty acids (FFA) content was detected. For mesophilic bacteria, 1.6 ± 0.1 log10 reductions were achieved, and for Enterobacteriaceae, there were close to 1.9 ± 0.2 log10 reductions in a layer of powder. Colonies of Bacillus cereus, Bacillus subtilis, and Bacillus megaterium were identified via the mass spectral fingerprint analyzed with matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS). The spores of these Bacillus strains resisted to a plasma power density of 22 mW/cm2. Additional inactivation effects at non-thermal, practically non-oxidative conditions are supposed for low-intensity plasma treatments combined with the powder's fluidization.

Effect of HHP, Enzymes and Gelatin on Physicochemical Factors of Gels Made by Using Protein Isolated from Common Cricket (Acheta domesticus).

The effect of high hydrostatic pressure (HHP) combined with enzymatic methods or gelatin incorporation in the gelation process of protein isolated from Acheta domesticus was investigated. The results indicate that transglutaminase (TGasa) or glucose oxidase (GOx) enzymes can induce reversible aggregation in dispersions of insoluble protein fractions and increase viscosity in dispersions of soluble fractions, but does not induce gel formation even after HHP treatment; in consequence, enzymatic treatment on cricket protein can be used to increase viscosity but not to form gels. It is technically feasible to obtain gels by adding 2% porcine gelatin to dispersions of protein fractions and subjecting them to HHP. The firmness and syneresis variation values of those gels during storage depended on the protein extracted fraction (insoluble or soluble protein) and on the concentration of protein used. The highest hardness and lowest syneresis was found with the gels obtained from the insoluble fraction at 11 and 15% (w/w) protein concentration. Color difference (ΔE* > 3) appreciable to the naked eye was observed along the storage period and no noticeable pH variations were found after 28 days of storage. Results indicate that new raw materials of interest can be developed for the food industry based on cricket protein isolates, to make high-protein foods which could be applied in a wide variety of different food applications including 3D printing or fat substitution.

Rare non-papillary lithiasis of calcium oxalate monohydrate generated on a central core of potassium urate.

This report describes a patient who developed a spheroidal calculus with a central part composed of potassium urate, surrounded by a continuous layer of calcium oxalate monohydrate with crystals of calcium oxalate dihydrate on the surface. The mechanism of calculus development is also suggested.

Benefits and Challenges in the Incorporation of Insects in Food Products.

Edible insects are being accepted by a growing number of consumers in recent years not only as a snack but also as a side dish or an ingredient to produce other foods. Most of the edible insects belong to one of these groups of insects such as caterpillars, butterflies, moths, wasps, beetles, crickets, grasshoppers, bees, and ants. Insect properties are analyzed and reported in the articles reviewed here, and one common feature is nutrimental content, which is one of the most important characteristics mentioned, especially proteins, lipids, fiber, and minerals. On the other hand, insects can be used as a substitute for flour of cereals for the enrichment of snacks because of their high content of proteins, lipids, and fiber. Technological properties are not altered when these insects-derived ingredients are added and sensorial analysis is satisfactory, and only in some cases, change in color takes place. Insects can be used as substitute ingredients in meat products; the products obtained have higher mineral content than traditional ones, and some texture properties (like elasticity) can be improved. In extruded products, insects are an alternative source of proteins to feed livestock, showing desirable characteristics. Isolates of proteins of insects have demonstrated bioactive activity, and these can be used to improve food formulations. Bioactive compounds, as antioxidant agents, insulin regulators, and anti-inflammatory peptides, are high-value products that can be obtained from insects. Fatty acids that play a significant role in human health and lipids from insects have showed positive impacts on coronary disease, inflammation, and cancer. Insects can be a vector for foodborne microbial contamination, but the application of good manufacturing practices and effective preservation techniques jointly with the development of appropriate safety regulations will decrease the appearance of such risks. However, allergens presented in some insects are a hazard that must be analyzed and taken into account. Despite all the favorable health-promoting characteristics present in insects and insects-derived ingredients, willingness to consume them has yet to be generalized.

In vivo Assessment of Cold Atmospheric Pressure Plasma Technology on the Bioactivity of Spirulina.

The present study challenges the in vivo assessment of cold atmospheric pressure plasma (CAPP) technology on the bioactive activity (antioxidant/antiaging and antimicrobial potential) of Spirulina powder, using Caenorhabditis elegans as an animal model. Surface microdischarge cold atmospheric pressure plasma (SMD-CAPP) treatment was 3.3 W discharge power for 7 min. C. elegans lifespan and egg laying were used as indicators of antioxidant/antiaging potential of Spirulina (1 mg/mL), when grown with Spirulina CP-treated [E_SCP] and untreated [E_S], compared with a control [E_0] (non-supplemented with Spirulina). According to our results, under both Spirulina supplemented media [E_SCP and E_S] and for the first 17 days, nematodes experienced an increase in lifespan but without significant differences (p > 0.05) between control and Spirulina CP-treated. Regarding the in vivo assay of the antimicrobial potential of Spirulina against Salmonella enterica serovar Typhimurium (infected worms), no significant differences (p > 0.05) were found between the three exposure scenarios (control [S_0]; Spirulina supplemented media [S_S]; CP-treated Spirulina supplemented media [S_SCP]). According to present results, CAPP-treatment do not influence negatively the lifespan of C. elegans but a reduction in the Spirulina antiaging potential was found. No in vivo modifications in antimicrobial activity seem to be linked to CAPP-processed Spirulina.