Food Grade Research Articles

Measuring the antimicrobial activity of natural extracts against food spoilage bacteria to enhance food hygiene: preliminary in vitro results

Food products are prone to microbial contamination able to affect their safety and quality attributes and their nutritional value. The interest in the potential use of bioactive compounds deriving from natural matrices, especially agro-industrial wastes, as alternatives to classical food preservatives has rapidly increased. In the present study a food grade olive mill wastewater polyphenolic extract and a commercial mix were characterised and their antioxidant and antimicrobial capacity were assessed. The antimicrobial activity was preliminary assessed in vitro by agar well diffusion, subsequently by microdilution method to define the minimum inhibitory and bactericidal concentration. The olive mill wastewater polyphenolic extract registered a higher antioxidant capacity [(13.3 ± 1.0) 102 µgTE/(100 g)] and antimicrobial efficacy (max MBC value 0.2500 g/mL) compared to commercial mix with wide potential application in food industry.

Is human perception reliable? Toward illumination robust food freshness prediction from food appearance — Taking lettuce freshness evaluation as an example

Machine vision-based food quality evaluation systems have achieved great attention in industry and academia in recent years because of their high-throughput and non-invasive properties. In practice, the environmental illumination conditions variations would cause visual evaluation bias for both human and machine perceptions. Compared to other existing studies which take sample images and human visual grading under fixed illumination conditions, this study first investigated the environmental illumination effects on the performance of visual-based food grading for both humans and machines. Taking lettuce samples as an example, an image dataset that considered the environmental illumination variations was first established. This dataset encompasses human visual grading scores obtained from sensory panels as well. In contrast to current studies that utilize a single grader or L*a*b* color features to assess sample freshness, our study reveals a substantial impact of environmental illumination on both human perception (p<0.0001) and L*a*b* color features (p<0.0001). In order to enhance the performance of machine vision-based freshness prediction, multitask learning protocols were incorporated into the proposed new network architectures. This allowed the simultaneous prediction of both sample freshness and illumination conditions. In comparison to commonly used generic convolutional neural network models and vision transformer models, the newly proposed model exhibited superior freshness prediction performance. It minimized the prediction error by 20.36%, outperforming the generic ResNet model. This research represents the first quantitative study addressing human and machine perceptions under varied illumination conditions for food quality evaluation. The findings are anticipated to play a pivotal role in expediting the integration of machine vision applications into food engineering practices.

An eco-friendly and up-scalable approach to extract canthaxanthin from yeast cells

Canthaxanthin is a naturally occurring ketocarotenoid pigment present in plants, algae, bacteria and some fungi. In addition to its coloring role, canthaxanthin has an excellent antioxidant activity, thus having additional market demands in the feed, food, cosmetic and pharmaceutical industries. Canthaxanthin can be directly isolated from its natural source or produced by chemical synthesis, but these strategies either result in low yields, or use hazardous solvents, respectively. Therefore, the biosynthesis of canthaxanthin using microbial cell factories is becoming an advantageous alternative. Furthermore, microbial synthesis represents an economic and sustainable approach as it enables the use of agriculture and industrial wastes as substrates. In this work, the extraction, recovery and purification of canthaxanthin from modified yeasts using food grade solvents and up-scalable methodologies was studied. The resulting canthaxanthin-enriched extract was characterized (UV-Vis, PXRD and SEM) and quantified (HPLC), resulting in a canthaxanthin purity of 43.7 % (w/w).

Non-destructive Near-infrared Hyperspectral Imaging in Food Technologies with a Focus on Monitoring Seed Viability

Seed qualities including viability and germination significantly influence the quantity and the quality of harvest. Technological means to assess seed qualities and attributes of seed-derived food products are varied. This paper highlights the use of infrared hyperspectral imaging (NIR- HSI) in food quality control, authentication, safety, process monitoring, shelf-life prediction, ingredients analysis, allergens detection and food sorting and grading. It also shows a particular application of NIR-HSI for the monitoring of nutrient content of sprouts and germinated seeds for industrial processing of foods with high nutritional values. The paper further reviews the applications of NIR-HSI to predict seed viability and germination. The non-destructive, rapid, and high-throughput capability of NIR-HSI were demonstrated through research works combining the NIR-HSI technology with chemometrics tools to reach more than 90% prediction rate. These relatively high rates may depend on the storage conditions or the stringency of the artificial aging conditions applied to parts of the seeds. However, the NIR-HSI has also proven efficient using naturally aged seeds with the prediction rates up to 90% correct classification, demonstrating the high capability of the technology. In combination with advanced chemometrics tools, some components of emerging technologies such as traditional machine learning and deep learning models have been added to increase the efficiency of NIR_HSI. Overall, the research works reviewed in this paper and which cover several food crops and food products showed that NIR-HSI is set to reach new heights in monitoring seed viability for improved seed stock management, crop production and innovation in the food industry.

A Sustainable and Cost‐Effective Bioadsorbent for the Removal of Allura Red from Contaminated Water

AbstractFood grade dyes pose severe health hazards when consumed in excessive amounts or enter body via contaminated water. Despite its harmful effects, Allura Red (AR) is very less explored dye for its removal, especially using agricultural/fruit waste. This study presents efficient removal of an important and unsafe food grade dye, AR via adsorption. Waste watermelon peel waste has been used for the first time for treatmenting wastewater contaminated with AR. Waste was converted to two types of adsorbents, with and without subjecting it to pyrolysis. Both the adsorbents were characterized for functionality and crystallinity and used for conducting adsorption studies. Removal of dye was evaluated by intrinsic strategy of monitoring the model solutions under pre‐ and post‐adsorption conditions. Removal percentage of dye was determined by calculating its initial (Co) and final (Cf) concentrations in solution using the formula (see Eq. (1)). Various reaction parameters important for adsorption, viz. pH, adsorbent dose, residence time, reaction temperature and particle size were optimized. Results indicate that ~80 % and &gt;92 % dye could be removed using 0.5 g/L adsorbent before and after pyrolysis respectively in 3.5 h from its 2 ppm concentration in modelled water.

Grades of cassava starch (flours) as sustainable substrates for use in neutral spirit and biofuel production—Industry approach

One way to mitigate the adverse impacts of climate change is through aggressive replacement of fossil energy sources with plant derived renewable energy. The potential of different grades of cassava starch, including decayed cassava starch, as viable alternative and cheaper source of renewable raw materials for bio-ethanol production was studied. The global population keeps expanding and poverty levels keep increasing. Conflict in the use of food-grade cassava starch as raw material for bio-ethanol production will pose a threat to food security. The highest alcohol yield (AY) of 539 LA/t dm was obtained from food grade cassava starch. Food grade cassava starch per-boiled for 5 min produced lower AY (524 LA/t dm). Cassava starch per-boiled for more than 5 min gave much lower AY (507 LA/t). The mildly decayed cassava starch gave a relatively higher AY of 491 LA/t dm than the more decayed cassava substrate that produced AY of 453 LA/t dm. The AY value obtained from the more decayed cassava starch is similar to the AY values obtained with some cereals. Decayed cassava is not fit for human consumption, would not compete with food requirements. This will assist in food security, secure our environment from pollution and other adverse effects.

Electrostatic interactions mediated defibrillation of β-lactoglobulin fibrils using Keggin Polyoxometalates

The whey protein β-lactoglobulin (βLG) forms fibrils similar to the amyloid fibrils in the neurodegenerative diseases due to its higher predisposition of β-sheets. This study shed light on the understanding different inorganic Keggin polyoxometalates (POMs) interaction with the protein βLG fibrils. POMs such as Phosphomolybdic acid (PMA), silicomolybdic acid (SMA), tungstosilicic acid (TSA), and phosphotungstic acid (PTA) were used due to their inherent higher anionic charges. The interaction studies were monitored with fluorescence spectra and Thioflavin T assay for both the βLG monomers and the fibrils initially to elucidate the binding ability of the POMs. The binding of POMs and βLG is also demonstrated by molecular docking studies. Zeta potential studies showed the electrostatic mediated higher interactions of the POMs with the protein fibrils. Isothermal titration calorimetry (ITC) studies showed that the molybdenum containing POMs have higher affinity to the protein fibrils than the tungsten. This study could help understanding formation of food grade protein fibrils which have profound importance in food industries.

An electronic equipment for marbling meat grade detection based on digital image processing and support vector machine

This work proposes an electronic equipment which determines the marbling grade in beef rib eye according to the American grading scale using digital image processing and machine learning, achieving an 88.89 % coincidence level with grading done by beef specialists. Existing solutions which use image processing usually require calibration methods due to working in non-controlled environments. Furthermore, they only acquire the fat distribution from the longissimus dorsi muscle with an approximate accuracy of 80 %, without referring the distribution to any quality standard. In this work, meat samples are placed in a food grade stainless-steel enclosure with a touch screen and a digital RGB camera. The device acquires an image of the rib eye, which is then analyzed using techniques such as adaptive histogram analysis based on the HSV color model, histogram peaks detection for grayscale thresholding and a linear Support Vector Machine (SVM). The SVM determines the marbling grade based on the American Standard and shows it via a graphical user interface. The classifier was compared with a k-Nearest Neighbors (kNN) and Random Forest (RF) models, to choose the one with the best performance for marbling grade prediction. The SVM and the kNN models obtained a better performance than RF in identifying the marbling level. The estimated American Standard grade was compared to gold standard reference tests performed by specialists from the National Agrarian University in Lima-Peru, where the SVM achieved the aforementioned 88.89 % coincidence level.

Effects of fatty acid esters on mechanical, thermal, microbial, and moisture barrier properties of carboxymethyl cellulose-based edible films

Fatty acid esters being biodegradable and environment friendly has been a sought-after class of molecule for various food grade applications. This work involves the incorporation of fatty acid esters namely cetyl-caprylate and cetyl-caprate in edible Carboxymethyl cellulose -based films. The esters were enzymatically synthesized by esterification of caprylic acid and capric acid respectively with cetyl alcohol at a molar ratio of 1:1, using Candida antarctica lipase B which was immobilized (10 % w/w) at 65 °C. Carboxymethyl cellulose films were prepared. To it, glycerol and by emulsification, cetyl-caprylate or cetyl-caprate esters were amalgamated. Film characterizations involved analysis of surface morphology, mechanical properties, and thermal properties. It was further characterized by X-Ray diffraction analysis, water vapor permeability, and moisture uptake. Barrier property carboxymethyl cellulose films showed significant improvement due to the incorporation of cetyl-caprylate or cetyl-caprate esters. However, when the film's melting point was measured, it was seen that glycerol influenced the thermal properties more prominently than cetyl-caprylate and cetyl-caprate esters. Thus, the addition of an optimized amount of glycerol and cetyl-caprylate or cetyl-caprate esters to the carboxymethyl cellulose films is required for improved mechanical strength and better thermal properties. Further, an antimicrobial well diffusion assay of both the esters established the antimicrobial property of the same, which thereby recommends the addition of the wax esters even more.

Targeted and untargeted screening of a plant extract library established from raw materials originating from Upper Austria

Plant extracts rich in phytochemicals are known for their health benefits. Plant extract library from edible plants obtained from the region of Upper Austria was prepared. Food grade extraction procedures were applied, and relevant physico-chemical parameters measured. A focus on polyphenolic compounds revealed a significant correlation between the total phenolic content (measured by a colorimetric assay) and the cumulated concentration of main individual polyphenols (measured by HPLC-DAD), demonstrating the comparability of these parameters. Targeted screening was performed by HPLC-FLD and −MS for the presence of phytomelatonin. 20 extracts were identified with concentrations of up to 1.4 µg/mL of this phytochemical, which attracts much attention from the food industry. Finally, chemometric methods were employed to cluster extracts based on their phenolic compound profile. This approach allows for an informed preselection of extracts without the need for comprehensive chemical analysis.

Efficient E/Z conversion of (all-E)-lycopene to Z-isomers with a high proportion of (5Z)-lycopene by food grade plant extracts

The conversion of lycopene from natural sources, mainly in all trans configurations, to cis configuration means a significant increase in bioavailability. However, the existing isomerization methods have problems with residual organic solvents, which limits the use of products. such as metal ion catalysis, electrocatalysis, and iodine-doped titanium dioxide (I–TiO2) catalysis. In this paper, the effects of common plant extracts on lycopene isomerization and its stability were investigated. Among them, sulforaphane and allicin showed significant catalytic effects, with sulforaphane being the most effective. Therefore, Broccoli sprouts were selected as a food component to investigate the catalytic isomerization of lycopene. After the optimization of pretreatment, the final content of sulforaphane was 5.81 mg/g. The cis-proportion of lycopene was elevated from 5% in the blank group to more than 60% when the treated broccoli sprout paste was added to the tomato paste. Also, the bioavailability of lycopene increased significantly with the increase in cis proportion. Compared with other isomerization methods, the method studied in this paper does not require any organic reagents and only uses food-grade materials such as allicin, sulforaphane, and broccoli sprouts to catalyze the cis-trans isomerization of lycopene.

One-step rapid formation of wrinkled fractal antibiofouling coatings from environmentally friendly, waste-derived terpenes

Wrinkled coatings are a potential drug-free method for mitigating bacterial attachment and biofilm formation on materials such as medical and food grade steel. However, their fabrication typically requires multiple steps and often the use of a stimulus to induce wrinkle formation. Here, we report a facile plasma-based method for rapid fabrication of thin (<250 nm) polymer coatings from a single environmentally friendly precursor, where wrinkle formation and fractal pattern development are controlled solely by varying the deposition time from 3 s to 60 s. We propose a mechanism behind the observed in situ development of wrinkles in plasma, as well as demonstrate how introducing specific topographical features on the surface of the substrata can result int the formation of even more complex, ordered wrinkle patterns arising from the non-uniformity of plasma when in contact with structured surfaces. Thus-fabricated wrinkled surfaces show good adhesion to substrate and an antifouling activity that is not observed in the equivalent smooth coatings and hence is attributed to the specific pattern of wrinkles.

3D Bioprinting of Food Grade Hydrogel Infused with Living Pleurotus ostreatus Mycelium in Non-sterile Conditions.

Mycelium is the root-like network of fungi. Mycelium biocomposites prepared by template replication (molding) can function as environmentally friendly alternatives to conventional polystyrene foams, which are energy- and carbon-intensive to manufacture. Recently, several studies have shown that 3D bioprinting technologies can be used to produce high value functional mycelium products with intricate geometries that are otherwise difficult or impossible to achieve via template replication. A diverse range of nutrients, thickeners, and gelling agents can be combined to produce hydrogels suitable for 3D bioprinting. 3D bioprinting with hydrogel formulations infused with living fungi produces engineered living materials that continue to grow after bioprinting is complete. However, a hydrogel formulation optimized for intricate 3D bioprinting of Pleurotus ostreatus mycelium, which is among the strains most commonly used in mycelium biocomposite fabrication, has yet to be described. Here, we design and evaluate a versatile hydrogel formulation consisting of malt extract (nutrient), carboxymethylcellulose and cornstarch (thickeners), and agar (gelling agent), all of which are easily sourced food grade reagents. We also outline a reproducible workflow to infuse this hydrogel with P. ostreatus liquid culture for 3D bioprinting of intricate structures comprised of living P. ostreatus mycelium and characterize the changes in height and mass as well as hardness of the prints during mycelium growth. Finally, we demonstrate that the workflow does not require a sterile bioprinting environment to achieve successful prints and that the same mycelium-infused hydrogel can be supplemented with additives such as sawdust to produce mycelium biocomposite objects. These findings demonstrate that 3D bioprinting using mycelium-based feedstocks could be a promising biofabrication technique to produce engineered living materials for applications such as mushroom cultivation, food preparation, or construction of the built environment.

Eco-Friendly and Self-Sanitizing Microporous Cellulose Sponge (MCS)-Based Cooling Media for Mitigating Microbial Cross-Contamination in the Food Cold Chain.

Maintaining precise temperature control is vital for cold chain food transport, as temperature fluctuations can cause significant food safety and quality issues. During transport, ice that melts can promote the growth of microbes and their spread, resulting in microbial cross-contamination. This study developed sustainable, non-melting, self-sanitizing "ice cubes" using food grade compositions including microporous cellulose sponges (MCS) and photosensitizers, aimed at enhancing temperature regulation and minimizing microbial contamination in the cold chain. Upon absorbing water, the MCS matched traditional ice in cooling efficiency and heat absorption and exhibit remarkable mechanical and thermal durability, withstanding multiple freeze-thaw cycles and compressive stresses. The cationic MCS combined with erythrosine B demonstrated strong self-sanitizing capabilities, effectively reducing microbial cross-contamination in food models. Additionally, the release rates of photosensitizers from the MCS can be modulated by altering environmental ionic strength. This research offers viable solutions to address microbial cross-contamination challenges in current cold chain systems.

Применение комплекса биологически активных веществ из Аronia melanocarpa в парафармацевтических фитоплёнках

The article presents the results of using non-pharmacopoeial plant raw material – dried leaves of the perennial cultivated chokeberry shrub Aronia melanocarpa (Michx.) Elliott. as a source of substances with anti-inflammatory and wound-healing effect. The development of a parapharmaceutical phytofilm based on a complex of biologically active substances from A. melanocarpa is described. The results of preclinical evaluation of the developed phytofilm in an experimental model of skin wound on outbred white rats are presented. The developed phytofilm is environmentally safe compared to synthetic analogues which production is accompanied by a negative environmental impact. Substances with antioxidant properties which can play the role of a medicinal base were found in the composition of aqueous extracts from chokeberry leaves: polyphenols – 7.4±0.7, tannins – 4.6±0.5 mg/cm3. The safety of using A. melanocarpa leaves as raw material for phytofilm has been confirmed in heavy metal tests. The composition and film-forming ability of chokeberry leaves aqueous extract, including polyvinyl alcohol (098-15(G)) (6%), food grade gelatin P-11 (0.5%), glycerin (GOST 6259-75) (0.4%), colloidal silver solution 200 mg/dm3 (1%) has been established. A. melanocarpa leaves extract application to the film-forming solution increases the final vapor permeability by 48% and solubility by 14%. The model experiment shows the effect of using the created phytofilm in the reparation of linear wounds, manifested as significant decrease in their length by 30% by the fifth day, by 25% by the seventh day compared with the control, as well as normalization of the skin histological structure by the tenth day.

Racial discrimination is associated with food insecurity, stress, and worse physical health among college students

BackgroundStudents of color disproportionately experience racial discrimination and food insecurity, which both lead to poor academic and health outcomes. This study explores the extent to which the location of racial discrimination experienced is associated with food insecurity, stress, physical health and grade point average among college studentsMethodsA cross sectional study design was implemented to survey 143 students from a racially diverse public university. Logistic regression models assessed if discrimination at various locations was associated with food insecurity and linear models assessed how racial discrimination was associated with physical health, stress and grade point averageResultsStudent’s experiencing food security had an average discrimination score of 2.3 (1.23, 3.37), while those experiencing food insecurity had a statistically significant (P < 0.001) higher average discrimination score 7.3 (5.4, 9.21). Experiencing any racial discrimination was associated with increased odds of experiencing food insecurity when experienced from the police (OR 11.76, 95% CI: 1.41, 97.86), in the housing process (OR 7.9, 95% CI: 1.93, 32.34) and in the hiring process (OR 6.81, 95% CI: 1.98, 23.48) compared to those experiencing no racial discrimination after adjusting for race, gender, age and income.ConclusionThe location in which a student experienced racial discrimination impacted the extent to which the racial discrimination was associated with food security status. Further research is needed to explore potential mechanisms for how racial discrimination may lead to food insecurity.

Solubility evaluation of palm-based Mono-diacylglycerols (MDAGs) in food grade solvent (hexane, ethanol, acetone, water) using QSPR model approach

Mono-diacylglycerols (MDAGs) are emulsifiers widely used in the food industry. MDAGs based on refined bleached deodorized palm stearin (RBDPS) have not been widely developed. MDAGs have been synthesized using glicerolysis between RBDPS and glycerols. Due to their low solubility in food-grade solvents (hexane, ethanol, acetone, and water), it has been difficult to purify or fractionate MDAGs only by a simple method. This research attempted to develop a model of MDAGs solubility in food-grade solvents and understand the parameters that influence the solubility of MDAGs in food-grade solvents. The process used a combination of experimental data collection and quantitative structure–property relationship (QSPR) models. The QSPR model for MDAGs solubility in a single and binary solvent demonstrated that the descriptors of Δ dipole moment (Δµ), E HOMO, E LUMO, electronic energy, gap energy HOMO-LUMO (ΔE1, ΔE2) softness (S), electrophilicity index (ω), and electron transfer (ΔN) have a significant impact in determining the solubility of MDAGs. Both the single and the binary solvents solubility models can give satisfactory prediction results: the square of the correlation coefficient (R2pred) was 0.933 and 0.948, and the root-mean-square error (RMSE) was 0.075 and 0.031, respectively, for the whole data set. In addition, this paper provided a new and effective method for predicting the solubility of MDAGs in single and binary food-grade solvent systems.

A New Formulation Addressing Base Resin Challenges and Carcinogenic Concerns for Water Pipeline Cathodic Protection

Traditional epoxy coatings used for water pipeline cathodic protection have several shortcomings, including limited availability, high cost, and carcinogenic concerns. To address these challenges, a new, food-grade epoxy coating that is affordable, meets all technical requirements, and is free of carcinogenic substances was developed.The study involved testing various kinds of reinforcing fillers, non-reinforcing pigments, red pigment, and BYK additives to formulate the epoxy-based coating. Curing experiments were then conducted by formulating the coating with a fixed ratio of curing agent and spraying the resins onto mild steel panels for testing.The results demonstrated that the new formulation has good compressive strength, adequate impact resistance, and Shore D hardness in the range of 60-70, which is expected for this type of application. The abrasion resistance of the coatings increased with increasing hardness.Overall, the new food-grade epoxy coating is a promising alternative to traditional epoxy coatings for water pipeline cathodic protection. It is affordable, meets all technical requirements, and is free of carcinogenic substances.Key words: Epoxy Resin, Coating, Food Grade, TETA

Modified ganyong (Canna edulis Kerr.) starch prospective as wheat flour alternative

Ganyong tuber (Canna edulis Kerr.) had high carbohydrate content and has potential to be used as starch. However, the starch obtained was low quality, characterized by brownish color and limited functional properties. The main aim of this work was to obtained the optimum process to transform canna starch into commercial wheat flour SNI 3751:2009 by oxidizing with food grade hydrogen peroxide (H2O2). The raw material used was white canna tuber from Samarinda, East Kalimatan which have high carbohydrate content. Initially, the starch was oxidized by 35% H2O2 food grade to form 1%, 2%, 3% concentration, slurry ratio of 10%, 20%, 30% and time of oxidation was 30, 60, 90 and 120 mins. The ganyong tuber starch was then subjected to modification process by optimizing the slurry ratio and H2O2 oxidation time. The assessment was based on basic functional properties, swelling power and water solubility. The process was conducted using a mini-propeller chamber, and data were collected in triplicates for accuracy. The optimum result was achieved with a 60-min oxidation time, 10% slurry concentration and 2% H2O2 concentration. The swelling power value reached 2.9 g/g, and water solubility was measured at 6.09 g/g. Upon proximate analysis, the canna starch contained 85.956% carbohydrates, 2.365% protein, 11.425% water and 0.254% ash content. The color analysis indicated a white degree with brightness of 91.95. Despite the improvements achieved through the process, the functional and other properties of ganyong starch were still considerably below of wheat flour standard.

Post-Marketing Surveillance of the World's First Novel Cocktail of Rabies Monoclonal Antibodies: TwinRab™ in Real \-World Setting.

Rabies presents with a high fatality rate, which imposes a significant global public health challenge, and therefore the use of post-exposure prophylaxis (PEP) is crucial for prevention. Monoclonal antibodies (mAbs) have emerged as a promising substitute for rabies immunoglobulins (RIGs) due to their high efficacy and standardized manufacturing process. A prospective, open-label, post-marketing surveillance study (PMS) was conducted at Byramjee Jeejeebhoy Medical College (BJMC), Pune. The study included patients aged more than 2 years who had recently sustained Category III-suspected rabid animal bite exposures. These patients were administered TwinRabTM at a dosage of 40 IU/kg in and around the wound as intralesional transfer, along with the anti-rabies vaccine (ARV). Adverse events (AEs) grading was performed with reference to the Food and Drug Administration (FDA) toxicity grading. In this study, 215 subjects received the TwinRabTM mAb with a 100% completion rate. Out of 215 patients, three (1.3%) patients in the range of 18 to 65 years of age showed solicited local AEs, which were resolved after the appropriate treatment intervention, but causality assessment was non-assessable. The overall tolerability assessment showed positive ratings from doctors (91.63%) and patients (67.91%) for the mAb cocktail. The PMS demonstrated the safety of TwinRabTM in patients who experienced Category III-suspected rabid animal bites, thereby supporting its potential as an alternative option for post-exposure prophylaxis in the management of animal bites for the prevention of rabies.