Amount Of Soluble Nitrogen Research Articles

Proteolysis in Mozzarella Cheeses Manufactured by Different Industrial Processes

The objective of the present study was to investigate the influence of stretching temperature, fat content, and time of brining on proteolysis during ripening of Mozzarella cheeses. Seventeen cheese-making experiments (batches) were carried out on an industrial scale on successive days, following the standard procedure with some modifications. Fat content of cheese milk, temperature at the stretching step, and time of brining varied from one batch to another as required by the experimental design, outlined by a surface response model. Proteolysis was assessed during ripening of samples, which was prolonged for at least 3 mo, by means of electrophoresis, nitrogen fractions, and soluble peptide mapping. The amount of soluble nitrogen at pH 4.6 was not significantly different in cheeses obtained by diverse procedures, but it increased during ripening of all samples. This result was coincident with the breakdown of αs1- and β-caseins evidenced by electrophoresis, which reached similar extents at late stages of ripening, regardless of the cheese-making process. Multivariate analysis on soluble peptide profiles obtained by liquid chromatography also detected sample grouping according to ripening time, but did not evidence any separation caused by the cheese-making technology. We concluded that the changes in the cheese-making process assayed in this work were insufficient to produce significant differences in proteolysis of the cheeses. Ripening time had more influence on proteolysis of Mozzarella cheeses than any other assayed variable.

Exploring the role of hydrogen peroxide in the microwave advanced oxidation process: solubilization of ammonia and phosphates

The focus of this study was to investigate the combined effects of hydrogen peroxide concentration and acid hydrolysis on ammonia and ortho-phosphate solubilization for subsequent struvite formation. A lower microwave temperature regime between 60 and 120 °C was of interest in this study because of the greater amount of polyphosphates found in the treated secondary sludge at these temperatures. At microwave-heating temperatures of 100 °C and 120 °C, it was found that increasing the hydrogen peroxide concentration resulted in an increased phosphorus and ammonia solubilization. At a reaction time of only 5 min, the combination of hydrogen peroxide and acid hydrolysis resulted in up to 61% of total phosphorus and 36% of TKN released into solution, as soluble ortho-phosphate and ammonia, respectively. The amount of soluble nitrogen in solution after microwave treatment was found to increase with the hydrogen peroxide concentration. Up to 39% of the total soluble nitrogen could be released into solution. Furthermore, the addition of hydrogen peroxide resulted in a dramatic decrease in the PO4:NH3 molar ratio, an important factor controlling struvite formation. In terms of facilitating poly-P breakdown into ortho-phosphate in the acid hydrolysis process, hydrogen peroxide was found to be the most effective at 80 °C and at a concentration of 1.5 wt% H2O2. At temperatures of 100 and 120 °C, the amount of soluble ortho-phosphate increased with the hydrogen peroxide concentration. Key words: advanced oxidation process, ammonia nitrogen, hydrogen peroxide, microwave, phosphorus release, sludge, struvite.

Impacts of soil acidity on qualitative and quantitative conditions of broadleaf and coniferous trees

To recognize the impacts of soil acidity on quantitative and qualitative conditions of broadleaf and coniferous trees in Syyahkal watershed region of northern Iran, hand-cultivated adjacent stands of different species of Pinus taeda, Acer insinge,and Alnus subcordata were compared. To gather general information about the soil type in each site, one profile and in total five soil profiles were dug, identified, and classified. In each site 35 individual plots have been selected and thus from all 175 plots available vegetative characteristics of above said tree species including height, diameter and volume have been determined. In order to determine the soil characteristiscs in each plot and based on our previous knowledge, samples from two specific horizon depths (0–15 cm., and 15–30 cm.) were collected. Then, in total of 135 samples specific chemical analyses of concern (pH, N.K.P) were carried out. Next, based on appropriate statistical studies (Student t-test, Fisher F-test, or ANOVA, Tukey test or HSD and regression analysis) the relation between vegetative characteristics of forest trees and different soil parameters in each adjacent sites have been compared. This comparison clearly showed that the hand-cultivated stands do not share similar vegetative characteristics status and in fact due to past thinning nurturing operations Pinus taeda has gained the most volume in acre. Statistical tests reveal that an increase in the amount of soluble nitrogen as a nutrient substance with regard to the vegetative parameters for all three plant species involved translates into a direct dependent relation. This means that an increase in tree diameter, height, and volume is expected wherever more concentrations of soluble nitrogen exists. The soil profile descriptive tables clearly show that Pinus taeda has taken root deep in the soil due to the lack of nutrients at soil surface layers. Thus, it would not be logical to suggest the re-plantation of this species in ruined forested areas of interest.

Influence of vegetable and animal rennet on proteolysis during ripening in ewes’ milk cheese

The renewed interest in using enzymes from thistles of the genus Cynara in the making of traditional ewes’ milk cheese prompted us to investigate the effect of vegetable and animal rennet on proteolysis during ripening of Los Pedroches cheese. Casein hydrolysis was found to be much more extensive and faster in cheese made by using vegetable rennet (the amount of soluble nitrogen at 60, 80 and 100 days of ripening was more than 28% greater than that in cheese produced using animal rennet). The levels of insoluble Tyr and Trp were higher in cheese produced with vegetable rennet. PAGE, using gels containing 7 M urea, revealed decreased contents in residual α s-CN and β-CN, as well as markedly increased levels of the more mobile components in cheese produced from vegetable rennet at the end of ripening. On the other hand, the degree of proteolysis in terms of NPN or its main components (peptides, amino acids and ammonia) was similar in cheese produced using animal or vegetable rennet.

Effect of Sulfur Deficiency on Protein Synthesis and Amino Acid Accumulation in Cell Suspension Cultures of Nicotiana tabacum

Summary Sulfur starvation in photoheterotrophic and heterotrophic cell suspension cultures of Nicotiana tabacum var. Samsun affects growth, protein synthesis and the accumulation of soluble nitrogen compounds. After depletion of the sulfate supply in the medium no further net-protein synthesis was observed and large amounts of soluble nitrogen accumulated. In photohete-rotrophically grown cells this accumulation was mainly due to an intense increase in arginine and glutamine which accounted for 70–85 % of the free amino acid nitrogen. In heterotrophically grown cells only a small amount of arginine was formed and glutamine was the predominant soluble nitrogen compound accumulated. In contrast to the changes in the free amino acid fraction, the protein content of the cultures remained constant during the early period of sulfur deficiency and the amino acid composition of the bulk protein did not change appreciably. Therefore it appears that the amino acids accumulating during sulfur deficiency have been produced by de novo synthesis. Under sulfur starvation conditions photoheterotrophically grown cells contained citrulline and ornithine which were not present in detectable amounts in suspensions grown on sulfur-rich media. The observed twofold increase in arginine production under sulfur starvation also indicates a stimulation of arginine synthesis by these conditions.

The effect of nitrogen source on levels of amino acids in peas

When nitrogen fixation in peas was partially replaced by nitrate assimilation as the source of nitrogen, an increase was found in the amount of soluble nitrogen that could be extracted from the fruits of the plants, and within this soluble fraction, increases were found in the levels of some of the acidic amino acids. Levels of protein amino acids in the peas were generally unaffected by the type of nitrogen source except for the level of aspartic acid which was about 20 per cent lower in peas supplied with nitrate. No differences were found in the proportions of the essential amino acids.

Leaching losses of nitrogen and potassium in polders reclaimed from Lake Ijssel

Mineral nitrogen and potassium lost from the Eastern Flevoland polder and from the North Eastern polder were estimated at regular intervals by determining the amounts of soluble nitrogen and potassium in the water which had been admitted by locks and inlets and discharged by pumping stations and subtracting nitrogen and potassium added in the rain. From 1959 to 1966 the nett annual losses of nitrogen in the discharged water from various pumping stations in Eastern Flevoland ranged from 18.9 to 33.2 (average 25.2) kg N per ha. Similarly in the North Eastern polder from 1963 to 1966 the nett annual losses ranged from 16.7 to 33.2 (average 22.1) kg N per ha.

スケトウダラの凍結による貯蔵

Alaska pollack tends to have “spongy meat” on frozen storage. It is suggested that vacuum freezing may be effective for this prevention because of the utilization of dehydration and quick freezing at the same time. In this study it was examined. Cut meat of Alaska pollock was frozen by three different methods, vacuum freezing, air blast freezing (3m/sec) at -35°C and still air freezing at -30°C, and stored at -25°, -15° and -5°C for 3 months. At a definite storage interval, the following determinations of samples were examined. Immediately after freezing, “spongy meat” was formed in samples of still air freezing. In those of the other freezings they were formed after storing for one month at -5°C. The amount of soluble nitrogen was constant for three months at -25°C storage, but at -5°C storage it decreased rapidly with the storage period. Expressible drip increased as storage period was longer, especially at high storage temperature. Taste became wrong with these changes. Alaska pollack was lost about 15% of moisture by vacuum freezing. This effect of dehydration would be shown as the ability of freezing preservation of Alaska pollack for 3 months at a temperature as high as -15°C without formation of “spongy meat”.

真空凍結乾燥スケトウダラの品質に及ぼす凍結速度の影響

Effect of the pre-freezing rate on the quality of lyophilized Alaska pollack was examined. The cut meats of Alaska pollack were freeze-dried at a platen temperature of 35°C and under a chamber pressure of 300 ?? 40μHg, after being frozen by vacuum freezing and still air fre-ezing at -30°C. After storing the sample at room temperature for a definite period, the qualities of the sample were estimated. When the cut meat of fish was frozen at a higher rate by vacuum, the tissue of lyophilized product was fine, whereas the one frozen at a slower rate formed a spongy meat. The amount of soluble nitrogen decreased on freeze-drying, especially after still air fre-ezing. After storing for one month, however, the protein practically denatured and there was no difference between the two samples. Immediately after drying, both samples re-absorbed water completely, but the water could easily be squeezed out again only by just applying a slight pressure. Organoleptically dried products when cooked, were not equal in texture to fresh fish. But they were quite palatable during the 3 months storage preriod, especially those forzen by vacuum freezing.

Proline Accumulation in Wilted Ladino Clover Leaves1

Ladino clover plants were allowed to wilt in the field and in the greenhouse to determine the effects of wilting on soluble nitrogen compounds. Wilting caused a slight decrease in total nitrogen but little change in amount of soluble nitrogen. A large increase in free proline occurred in all wilted leaves. Free asparagine was abundant in unwilted leaves but varied considerably during wilting. Other free amino acids occurred in small amounts. Only traces of glutamine were found.Two light intensities were used in the greenhouse experiment. During severe wilting, the higher intensity stimulated proline synthesis. The results suggest that proline accumulation during wilting is influenced by available carbohydrate.The results of these experiments show that marked changes in free nitrogen compounds occur during wilting. These changes may aid in conserving nitrogen and carbon during moisture stress.

Der Einfluss von Farblicht auf Wachstum und Zusammensetzung Pflanzlicher Gewebekulturen

The growth of green cultures of callus tissue from Nicotiana tabacum var. “Samsun” is stimulated by light. To determine whether the increase in growth is caused by photosynthesis or by a blue light dependent increase of protein synthesis, a comparative study was made of the effect which blue and red light have on the growth and the composition of tobacco tissue. It is shown that the growth stimulation by light depends on the chlorophyll content of the tissues. Starting with chlorophyll-free tissue the cultures begin to grow faster in blue light only after they become visibly green. On the other hand, the growth of green tissue in red light decreases as soon as the chlorophyll content under this condition becomes less. There are no differences in the rate of growth of green tissues cultivated in blue and in red light of approximately the same flow of quanta; in both cases the cultures grow better than the controls in the dark. Furthermore there are no differences between the protein and carbohydrate content of tissues grown in blue or red light and in the dark. There is, however, a small but significant difference between the total nitrogen of green tissue and that of chlorophyll-free tissue which is due to a higher amount of soluble nitrogen in the green tissue. From these results it is concluded that the light dependent growth stimulation is caused by photosynthesis. As shown by a light dependent 14CO2 incorporation in which sucrose is the main product, the green cells are able to fix CO2 photosynthetically. However, the rate of photosynthesis in the tissue cultures is small and does not balance the respiration. It seems very unlikely, therefore, that the formation of carbohydrates by photosynthesis is responsible for the observed growth increase.

Residual effect of nitrogen fertilizer on succeeding crops in a moderate marine climate

Residual effects of fertilizers have been observed frequently; those of phosphorus may last several years. Though the soluble nitrogen in a humid climate is subject to vigorous leaching, recent investigations (Harmsen5, van der Paauw 9, Baumann x) have shown that the value of the amount of soluble nitrogen in the whole rooting zone for the nitrogen supply of the crop should not be underestimated. This amount depends largely on the intensity of rainfall, especially in winter, and on soil properties. Large residual effects of nitrogen applied to the preceding crop are mentioned in literature (Crowther 2, Jacquot 7, Hunter and Yungen6, Pearson et al.1*). White, Dumenil and Pesek14 paid much attention to the problem. Residual effects corresponding to from 0 to 49 per cent with an average of ca 25 per cent of the effect of a fresh fertilization (Dumenil 3) were found for oats or corn succeeding corn. These responses were especially large after dry seasons. Considerable differences in nitrate content in different years were observed in the 6-21 inch depth of soil (White and Pesek14). It is of interest to know whether similar effects also occur under

A Study of the Ripening of Dariworld and Cheddar Cheese with Special Emphasis on Proteolysis

Summary Smooth, waxy consistency and desirable processing characteristics develop more rapidly in Dariworld than in Cheddar cheese. Measurements of soluble nitrogen and formol nitrogen were made of both varieties during 5 mo. of ripening to learn if rates of proteolysis might explain these differences in consistency. Observations were made at five different stages of ripening on two lots of each variety, one lot of which was normal and the other abnormally high in pH. Rates of proteolysis were essentially alike in the normal lots of both varieties and in the Cheddar with high pH. The sweet Dariworld which, unlike the sweet Cheddar, retained its high pH during ripening, showed the most rapid and extensive protein decomposition. Both of the sweet lots, however, were hard and woody in consistency and did not improve as amounts of soluble nitrogen and formol nitrogen increased during ripening. Acidity developed in making the sweet modifications evidently was insufficient to effect normal partition of minerals between whey and curd, and the resulting abnormal composition of curd apparently caused the defects in body. Rapid loss of curdiness in the ripening of normal Dariworld was not caused by unusually fast protein breakdown. Physico-chemical changes caused by the prolonged exposure of the curd to sodium chloride brine during the making operation of this cheese and the relatively high moisture content evidently account for its characteristic consistency.

The Effects of Corn Residue, Nitrogen, and Incubation on Nitrogen Release and Subsequent Nitrogen Uptake by Oats: A Quantitative Evaluation

A fertile Clarion loam soil was treated with rates of corn residue and nitrogen and incubated at approximately 30° C. for different periods under controlled moisture conditions. After incubation, half of the treated soils were leached to remove the soluble nitrogen. Inorganic nitrogen determinations on the leachate were used to study the effects of the treatments on nitrogen release. Regression equations were used to express inorganic nitrogen yield as a function of time. The first derivatives of these equations were used to estimate the time, in days, at which the “maximum” inorganic nitrogen immobilization or minimum amount of soluble nitrogen occurred for each level of nitrogen. These time values were used to estimate the maximum quantities of nitrogen immobilized at each nitrogen level. The results indicate that in fallow-incubated soils that had received residue, the “maximum” quantity of inorganic nitrogen immobilized increased as the quantity of applied nitrogen was increased. However, after the estimated minima of the curves were passed, the net rate of mineralization also increased with the rates of nitrogen. The leached and unleached soils were cropped with oats, which was harvested at the boot stage. Dry matter yield and nitrogen yield curves were used to evaluate the various treatment effects. The results indicate marked responses to the residue, nitrogen, incubation, and leaching treatments. The various yield curves indicate that the immobilized nitrogen was released to the crop. The leaching technique used in this experiment is shown to be an excellent method for evaluating net nitrogen transformations. This technique may have applicability in studying other mobile soil nutrients and also, the effects of applied fertilizers on the release of other soil or fertilizer nutrients.

207. Protein metabolism and acid production by the lactic acid bacteria in milk. Influence of yeast extract and chalk

Though the lactic acid bacteria are recognized primarily as saccharolytic, several workers have recorded observations on their slow proteolytic activity. Von Freudenreich(1) was the first to record the fact that cultures of these organisms in milk, to which chalk had been added to neutralize the acidity, formed appreciable amounts of soluble nitrogen, and these findings were confirmed by Orla-Jensen (2), Barthel(3), and Barthel & Sandberg(4). Anderegg & Hammer (5), in a study of a large number of strains ofStr. Lactis, found an increase in soluble nitrogen in some cases and a decrease in others, while occasionally the same strain differed in different tests. In general, cultures which clotted rapidly were more inclined to proteolysis than those which were slower in forming acid.Str. citrovorusandStr. paracitrovorusdid not cause protein breakdown. Addition of 0·3% peptone to the milk tended to retard proteolysis or to increase negative values while addition of chalk resulted in more extensive proteolysis. Barthel & Sadler (6) found that starters consisting of mixed cultures of streptococci produced more extensive proteolysis than single species, indicating a symbiotic effect. Sherwood & Whitehead (7) tested the proteolytic powers of several strains ofStr. cremorisin chalk milk cultures and found some active and some comparatively inactive. Two strains appear to have formed surprisingly large amounts of non-protein nitrogen. In general they found that acid-producing power was linked with proteolytic power.

餌料生物の化學的研究

The analysis of marine plankton have been worked out by BRANDT (1898), BRANDT and RABEN (1919-22), MEYER (1914), MOBERG (1926) and WIMPENY (1929) for its protein, fat, ash, carbohydrate or chitin contents. The seasonal variation of fat and protein contents of Calanus in Clyde Sea-Area was recently studied by ORR (1934), MARSHALL, NICHOLLS and ORR (1934). On the other hand, KNAUTHE (1901), NAKAI (1921) and BIRGE & JUDAY (1922) have given analytical data of fresh water plankton and benthos. The inorganic constituents and protein digestiblity of Crustacea, Mollusca, Worms, and other organisms as fish foods have never been studied. The present paper deals with the chemical composition of them with special reference to their inorganic constituents, namely, calcium, magnesium, phosphorus, iron, copper, sulphur, and iodine contents, chitin, and the protein digestibility. Thirteen kinds of organisms were analysed by using ordinary methods for total nitrogen, protein nitrogen, crude fat and crude ash content. R. PINCUSSEN'S micro-method (1928) was employed for determining the amounts of inorganic constituents. Chitin was measured by using the method of BUXTON (1932). The kinds and analytical data are given in Tab. 1. Comparative study of protein digestibility was made by using pepsin and eel protease which was extracted from stomachal membrane of Anguilla japonica (optimum temp. 37°C, opt. pH 3.2). For the digestibility the soluble nitrogen liberated during digestion at 37°C was taken as a measure. The pH value of digestive mixtures were held at 2.0 for pepsin and at 3.0 for the eel ferment using citrate buffer solution. The protein digestibility (D) was calculated by the following formula: D=S1-S0/N×100, where S0 and S1 are amounts of soluble nitrogen at outset and 24 hours afterwards respectively, and N denotes the total nitrogen of the samples. The results of the experiment are given in Table 2 and 3, and shown in Fig. 1. It will he seen from Fig. 1 that similar digestibility is obtained either by pepsin or by eel ferment. It is also to be seen in the same figure that chitin content of the material is reversely correlated with the protein digestibility.

On the Chemical Changes Produced in Flour by Bleaching

The action of air containing nitrogen peroxide upon flour, in quantities up to 300 c.c. of nitrogen peroxide to one kilogramme of flour, may be summarised as follows:—I. The golden-yellow tint of the flour is destroyed. Immediately after bleaching no difference in tint due to excess of the bleaching agent could be observed with Lovibond's tintometer, but on keeping for several days the more highly bleached samples became decidedly yellow, while those treated with 30 to 100 c.c. of nitrogen peroxide per kilogramme became still whiter, the maximum of bleaching effect being attained within these limits.II. The amount of nitrous acid or nitrites present in a freshly bleached flour is approximately proportional to the amount of nitrogen peroxide employed, and corresponds to about 30% of the total nitrogen absorbed, rising to 40% in the more highly bleached samples. After the lapse of several days, the proportion of nitrites present decreases considerably in the higher concentrations, but remains very nearly the same in the more slightly bleached samples.III. Approximately 60% of the total nitrogen introduced as nitrogen peroxide into the flour during bleaching can be recovered as ammonia a short time after bleaching by reducing the aqueous extract of the flour with a copper-zinc couple, and may be assumed to be present in the flour as nitric and nitrous acids or as nitrates and nitrites. After keeping the bleached flour for some days the amount of nitric acid extracted with cold water decreases. Experiments with pure glutenin and gliadin indicated that in certain circumstances nitric acid may be withdrawn from solution or “adsorbed” by these proteins.IV. In highly bleached flour a considerable increase in the amounts of soluble proteins and soluble carbohydrates takes place. If one kilogramme of flour is bleached with 300 c.c. of nitrogen peroxide, the amount of soluble nitrogen is doubled. This appears to be due almost entirely to the solubility of gliadin in nitric acid of certain concentrations. The simultaneous increase of soluble carbohydrates would seem to point to an intimate relationship between the gliadin and certain carbohydrates in flour.V. If highly bleached flour is allowed to stand for some time after bleaching, the oil undergoes very considerable alteration and acquires the characteristics of an oxidised oil. About 6 to 7% of the nitrogen introduced as nitrogen peroxide during bleaching is absorbed by the oil.VI. The absorption of nitrogen peroxide by flour does not appear to be accompanied by the production of free nitrogen, nor was any evidence obtained of the formation of diazo-compounds.VII. Sodium nitrite was found to exert no inhibitory action on the digestion of soluble starch by saliva, but the rate of digestion was greatly retarded if the starch had been previously treated with nitrogen peroxide gas. Bleaching was found to exercise an inhibitory effect on the salivary digestion of flour.