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This study aims to describe the development of a battery-operated portable colorimeter for on-site determination of water quality in aquaculture.

A simple and economical colorimeter is built using light sources of different wavelength and a light-dependent resistor combined with an electrical circuit. The whole system was fabricated as to fit into the pocket or palm for easy handling. The developed portable colorimeter was calibrated for estimation of nitrite. Further, the performance of developed portable colorimeters was compared with the commercially available colorimeter.

Three colorimeters with different light sources were developed and calibrated for determination of nitrite in water. Among them, colorimeter with yellow light source exhibited higher potential for determination of nitrite in the range of 0.5–3.5 ppm. Further, the results of the developed colorimeter are comparable with the commercial colorimeter.

The portable colorimeter developed in this study exhibits potential for determination of nitrite in aquaculture. Determination of nitrite at low concentrations is important for assessing the quality of culture as well as wastewater in aquaculture industry. The accuracy, portable nature, economy and simple operation of these portable colorimeters offer opportunity for on-site determination of water quality parameters in aquaculture.

The curing of pork for the purpose of manufacturing bacon and ham is fundamentally a process of salting that was originally used merely as a method of preservation. A century and a half ago the curing of pork was done on the farm or in the home. To‐day, practically all the bacon and ham consumed is mass‐produced in factories, and the concern of manufacturers is to obtain the best standard products by the simplest means. The report that follows is not concerned with those factors in the quality of the product that can only be standardised by control of the conditions under which the pig is reared and of its treatment immediately before slaughter, such as the conformation and composition of the carcase. It is concerned only with those factors that are definitely due to the process of curing, namely, the cured flavour, the production of the red cured colour of the lean meat and the even distribution of salt. It is now well known that the production of the red colour is due to the interaction of a nitrite, such as potassium or sodium nitrite, with the haemoglobin of the meat, which yields a pigment, nitroso‐haemoglobin, which is more permanent than haemoglobin. On the other hand, it is known that such nitrites may have harmful effects upon animals, if taken indiscriminately into the alimentary system, so that the view generally held is that the amount of nitrite in staple foods should be as low as possible. In the traditional method of curing, nitrite is not added to the curing salt. Nitrate (saltpetre) is added. The fact that the red colour develops is due to the action of certain bacteria in reducing a portion of the added nitrate to nitrite. In this indirect method of introducing nitrite into the cure, the amount of nitrite in the product when it is finally consumed depends upon many variables, and cannot be easily or strictly controlled. The traditional procedure of adding nitrate is still the basis of commercial practice in this country ; in fact, the addition of nitrite is illegal. The traditional method of curing on the farm or in the home has, however, been modified in one very important way in the modern factory. Traditionally, dry salts were used. To‐day, the usual method employed in factories is salting by immersion in tanks of pickle, combined with the forcible injection into the carcase of a solution of common salt and saltpetre. Two advantages have been gained by this change ; first, a milder cure, containing a relatively small and fairly evenly distributed amount of salt, and, secondly, speed and economy. From the points of view both of the consumer and of the manufacturer, a number of questions emerge from this review of the present situation in this country. Thus, it may be asked : (1) Does nitrate contribute in any essential way, in addition to serving as a source of nitrite, to the process ? Does it, for example, contribute essentially to the cured flavour or to the keeping properties of the product ? (2) Similarly, do bacteria contribute in any essential way, in addition to acting as agents in the production of nitrite ? (3) How far are the temperature, time and acidity determined in tank‐curing by the need for controlling the type of bacterial flora and its activity ; and what advantages could the manufacturer obtain if the need for the bacteria and for the control of their activity did not exist ? (4) Would the elimination of the nitrate and the bacteria from the process help toward obtaining more uniform and lower amounts of nitrite in the finished product ? It has therefore been felt essential to carry out the experiments described in this report, although it may appear at first sight that they cover similar ground to that traversed as long ago as 1925 in the U.S.A. under the auspices of the Bureau of Animal Industry of the United States Department of Agriculture and of the Institute of American Meat Packers. There is, however, a basic difference in the aims of the two pieces of work. The American work, conducted on an extensive scale in a number of packing houses, was a successful demonstration that the direct use of sodium nitrite in American cures was commercially practicable, and had many operative advantages over the traditional method, which relied entirely for the production of nitrite on the bacterial reduction of nitrate. As regards the product, it was found to be at least equal in all respects to that produced by the older method. The work was not designed to elucidate the mechanism of curing, i.e., to isolate the factors responsible for the production of the cured flavour and, in fact, no steps were taken to eliminate the factor of bacterial action. The results did, however, show that the presence of nitrate, as such, was not essential for the flavour of American bacon and hams. The aim of the present work has been twofold : to determine the relative importance of the various factors responsible for the production of the cured flavour ; and to determine whether the direct use of nitrite in English cures, which are very different from those used in America, would give a satisfactory product, as judged by English standards. The first objective is not only of scientific interest, but is fundamentally related to the second. If a clearly defined factor can be shown to be responsible for the production of the cured flavour, any consequential modifications in English commercial practice that may suggest themselves can be viewed and developed on a scientific and not an empirical basis. The work therefore included a critical comparison between, first, current procedure in the factory, based on the traditional process of adding nitrate and depending on bacterial activity for the production of nitrite ; secondly, nearly sterile procedure in which both nitrate and nitrite were added in addition to sodium chloride ; and thirdly, nearly sterile procedure in which only nitrite was added. Other aspects of curing were also investigated, including the rate at which the freshly‐slaughtered pig is cooled, the action of heat on the nitrite in bacon, the minimal desirable amount of free nitrite in bacon, the bacterial flora of pork, bacon and mature tank‐pickle and the amounts of salt and nitrite in commercial bacon. The results of the experimental cures, as will be seen, establish a strong presumption that the characteristic flavour of bacon is due to the action of sodium chloride and nitrite on the flesh, and that the presence of nitrate and microbial action during pickling and maturation are not essential. The work also raises, but does not settle, other important issues. For example, what is the process by which nitrite is lost in the meat, other than by combination with haemoglobin, and what are the effects of temperature, time, acidity, etc., upon the rate and extent of this process ; does the presence of nitrate in the tissues appreciably retard or inhibit the growth of putrefactive anaerobes? These problems are now being investigated, but in the meantime it seems undesirable to defer publication of the results already obtained. What is the immediate practical upshot of the work ? The basic principles of the curing of bacon can be taken as fairly established, and they do point to the possibility of recasting current practice in this country in a way that would give the curer really effective control over the quality of his product, so far as it is determined by the actual process of curing. But it would be premature at this stage to attempt the radical changes in method that are implied. Before that could usefully be done it would be necessary to carry out a comprehensive series of experiments on a larger scale, and with an adequate range of raw material (i.e., carcases), in order to establish how far the results obtained on the small scale are reproducible in the factory. The question of this further work is under consideration.

The purpose of this paper is to analyse the content and some synthetic food colourants, total fats, nitrate and nitrite in both advertised foods (AF) and serum and urine samples of children (8 to 12 years) and their impact on childrens’ diet and health.

Analysis of the content of the AF was done by watching the three Egyptian children’s channels (ECC) for 38 hours. Amaranth, Indigo Carmine, Tartrazine, nitrate and nitrite were analysed in all AF and in serum and urine specimens of children. However, total fats were only analysed in the advertised processed meats and in the restaurant dishes. Lipid profile was also estimated in children.

The AF accounted for 46-54 per cent of the total advertisements presented. The advertised restaurant dishes were predominantly high in fats, 63 and 55 per cent in restaurant dishes and processed meats, respectively. Tartrazine was the only food colourant found in soft drinks and jelly powders measuring 0.2-15 µg/ml and 25-125 µg/g, respectively. The average levels of total nitrate and nitrite were higher than the acceptable daily intake of the Egyptian and WHO limits (125 mg/kg). Urinary Tartrazine and serum and urinary total nitrate and nitrite were significantly higher in the viewers’ children for the ECC and at borderline for lipid profile compared to non-viewers’ children.

The most harmful effect of these advertisements is the cumulative effect of AF that undermines progress towards a healthy diet for children. AF may expose children to non-communicable disease in the future.

The local policy context requires action to set clear rules for children’s food advertising and monitor processed meat products to tackle exceeded levels of nitrate and nitrite.

This is one of the first studies to analyse colourants, fats, nitrate and nitrite in AF and in the serum and urine of children. This research shows a large number of AF (1,112) in the ECC for 38 hours with statistically significant increase of Tartrazine, nitrate and nitrite in AF (p<0.0001) and in biological fluids (p<0.05).

Two corrosion inhibitors for closed cooling water systems, nitrite-based and mixture of nitrite and molybdate corrosion inhibitor, are often compared to each other. This study aims to optimize these two inhibitors in terms of concentration and pH for carbon steel protection, with insights into the double layer structure on surface and its impact on corrosion inhibition.

Electrochemical analysis including electrochemical impedance spectroscopy and potentiodynamic test are carried out for quick assessment of corrosion inhibition efficiency and optimization, which is confirmed by immersion test and microscopic analysis. The electronic properties of the surface film are analyzed through Mott–Schottky method which provides new insights into the inhibition mechanism and the role of each component in mixture inhibitor.

Mixture of nitrite and molybdate is shown to present higher inhibition efficiency, owning to the double layer structure. Nitrite alone can form a protective surface film, whereas molybdate leads to an n-type semiconductive film with lower donor density, hence giving rise to a better inhibition effect.

Surface after inhibitor treatment has been carefully characterized to the microscopic scale, implying the effect of micro-structure, chemical composition and electronic properties on the corrosion resistance. Inorganic corrosion inhibitors can be tuned to provide higher efficiency by careful design of surface film structure and composition.

Almost every study on corrosion inhibitor applies such method for quick assessment of corrosion inhibition effect. Mott–Schottky test is one of electrochemical methods that reveals the electronic properties of the surface film. Previous works have studied the surface layer mainly through X-ray photoelectron spectroscopy. This study provides another insight into the surface film treated by nitrite and molybdate through Mott–Schottky analysis, and relates this structure to the corrosion inhibition effect based on multiple analysis including electrochemistry, microscopic characterization, thermodynamics and interface chemistry.

Zinc ions, produced by the electrolytic dissolution of zinc metal rods, exhibited excellent inhibition efficiency, especially in combination with the synergistic additions of tungstate and nitrite ions. The optimum ratio of tungstate: nitrite: zinc was found to be 10:10:1 and the combination of tungstate: 100 ppm ‐ nitrite: 100 ppm ‐ zinc: 10 ppm (System A) gave the best results of all the systems studied. This system requires a much smaller concentration of tungstate and nitrite ions, as compared to the concentrations typically used and claimed to offer optimal inhibition efficiency. Long‐term open circuit potential measurements indicated that effective passivation occurred within 3 days of immersion. The passive layer thus formed on the metal surface retained its protective capability for several weeks, even after test coupons were transferred into a depleted inhibitor solution. The possible mechanism of the passivation is discussed.

Fumes, grit, dust, dirt—all have long been recognized as occupational hazards, their seriousness depending on their nature and how they assail the human body, by ingestion, absorption, inhalation, the last being considered the most likely to cause permanent damage. It would not be an exaggeration to state that National Insurance (Industrial Injuries) provisions, now contained in the Social Security Act, 1975, with all the regulations made to implement the law, had their birth in compensating victims of lung disease from inhalation of dust. Over the years, the range of recognized dust disease, prescribed under regulations, has grown, but there are other recognized risks to human life and health from dusts of various kinds, produced not from the manufacturing, mining and quarrying, &c. industries; but from a number of areas where it can contaminate and constitute a hazard to vulnerable products and persons. An early intervention by legislation concerned exposed foods, e.g. uncovered meat on open shop fronts, to dust and in narrow streets, mud splashed from road surfaces. The composition of dust varies with its sources—external, atmospheric, seasonal or interior sources, uses and occupations, comings and goings, and in particular, the standards of cleaning and, where necessary, precautions to prevent dust accumulation. One area for long under constant scrutiny and a subject of considerable research is the interior of hospital wards, treatment rooms and operating theatres.

The purpose of this paper is to investigate how to improve the corrosion inhibition behavior of molybdate‐based inhibitors for mild steel, using organic compounds containing a phenyl ring together with nitrite agent. As picrate contains a phenyl ring together with three substituent nitrite anions, it is used as an organic compound. In this study a new molybdate‐based inhibitor was introduced with the composition of 60 ppm molybdate/40 ppm nitrite/20 ppm picrate. Inhibition efficiency of molybdate alone and with nitrite and picrate on the uniform corrosion of mild steel in stimulated cooling water was assessed.

The inhibition efficiency of molybdate alone and with nitrite and picrate on the uniform corrosion of mild carbon steel in stimulated cooling water (SCW) was assessed by electrochemical techniques such as potentiodynamic polarization, electrochemical impedance (AC impedance) measurements and weight loss determinations at the room temperature. Studies of electron microscopy included scanning electron microscopy (SEM) photography and X‐Ray energy dispersive (EDS) microanalysis were used.

The results obtained from the polarization and AC impedance curves were in agreement with those from the corrosion weight loss results. The results indicated that the new inhibitor was as effective as molybdate alone, though at one quarter of the concentration range of molybdate, which is economically favorable.

The paper demonstrates improvement in corrosion inhibition of mild steel in SCW via a blend of molybdate, nitrite and picrate as a new anodic inhibitor.

This paper aims to study the influence of the addition of calcium nitrite on the passive films of rebar to reveal what causes calcium nitrite to further prolong the durability service life of the reinforced concrete structures.

A comprehensive experimental study of the passive films, such as components, surface morphologies, electric structure and compactness, was carried out in a saturated calcium hydroxide solution which is normally used to simulate concrete pore solution by using X-ray photoelectron spectroscopy, atomic force microscopy, Mott–Schottky and potentiostatic polarization, respectively.

The results showed that the passivation behavior of rebar has been changed dramatically by the addition of calcium nitrite. That is, the passive film formed in the solution with the addition of 10 g/L Ca(NO₂)₂ had less donor density (Nd), more positive plat potential, smoother surface and lower content of Fe_hydrox than that formed in the solution without Ca(NO₂)₂.

The study focuses on the passive films and provides a more clear cognition of the durability service life extension of the reinforced concrete structures caused by the addition of calcium nitrite.

Green leafy vegetables (GLVs) are important components of a balanced diet especially in developing countries where the major requirements of micronutrients are met. However, GLVs also contain significant amounts of oxalate, nitrate and nitrites, whose role in the human diet is constantly changing. The current study explored the behavior of nitrate, nitrites and oxalate in lactic-fermented GLVs with an intention to develop functional foods based on them.

Selected strains of beneficial lactic acid bacteria were used for the controlled fermentation of GLV, while an identical portion was subjected to spontaneous fermentation. The nitrate and nitrites were monitored spectrophotometrically, while oxalate contents were quantified by both titrimetric and by high-performance liquid chromatography throughout the duration of fermentation.

More than 90 per cent of individual constituents studied remained intact in the GLVs paste after the six-day controlled fermentation period. However, there was significant difference between the controlled and spontaneously fermented samples in terms of oxalate, nitrate and nitrite contents.

Controlled lactic fermentation although superior in all other aspects may not be able to lower the anti-nutrients present. The advantages of spontaneous fermentation vis-à-vis controlled fermentation are discussed. The work will bring out the importance of the beneficial effects of GLVs and the effect of lactic fermentation.

Considerable attention has been paid in the last few years to a class of compounds called ‘Nitrosamines’ which could be formed in foods as the result of a reaction between nitrites and amines. In certain species of laboratory animals under specific conditions, some of these nitrosamines have been shown to be carcinogenic. Food scientists have had to look at the use of nitrites in foods and have had to establish whether there is any possible danger in their use