Kjeldahl Technique Research Articles

Assessment of Heavy Metal Contamination and Potential Health Risk of Selected Fish Species in Dhaka District

Fish is a rich source of quality protein and fatty acids. Bangladesh's average daily fish consumption is 67.8 grams per people. Fish species are also prone to heavy metal contamination from their surrounding environment. The main objective of this research was to assess the degree of risk associated with the consumption of various fish species in Dhaka, Bangladesh. Three fish species—Tilapia (Oreochromis mossambicus), Shorputi (Systomus sarana), and Mola (Amblypharyngodon mola)—from three local markets in Savar Union, Dhaka, Bangladesh, were selected for analysis. The Kjeldahl technique, Folch method, and several formulae were used to determine the protein, fat, ash, and moisture content for the proximate analysis. The concentration of heavy metals was determined using Atomic Absorption Spectrophotometry (AAS). The estimated daily intake (EDI), target hazard quotient (THQ), total target hazard quotient (TTHQ), hazard index (HI), and cancer risk (CR) were used to evaluate the danger to human health. Tilapia had the highest moisture and lipid content, whereas Shorputi and Mola had the highest protein and ash contents, ranging from 20.77% to 18.16%, respectively. The mean concentration of heavy metals in fish was determined to be Pb>Ni>Cr>Cd in this study. Every fish species had extremely high levels of lead (Pb), with the Shorputi fish having the highest levels. Fish from the Shorputi species had the highest EDI value. Pb>Ni>Cr>Cd was the trace element EDI for adults. Among all species, only Pd had a THQ value higher than 1. The CR value across all species were within E-3 and E-6 range, while the HI value was >1. In conclusion, the highest average Pb concentrations were detected in Shorputi, while the highest amounts of Cd, Cr, and Ni were observed in Tilapia. The findings of this study recommended that the Bangladeshi government regularly assess the levels of dangerous heavy metal and metalloid contamination in the daily meals of its citizens in order to enforce regulatory limits and determine the likelihood of long-term exposure. Bioresearch Commu. 10(2): 1524-1531, 2024 (July)

Effect of Addition Tempeh Flour on Calcium, Protein, Water Content and Acceptance in Catfish Meatballs

Introduction: More than 50% of women in each country suffer from dysmenorrhea.This can be painful during menstruation and affect 50% of a woman’s daily activities. Calcium can reduce muscle cramps after contractions. Tempeh and catfish are calcium-rich foods that people often eat, but the variety of processed products available is limited. The purpose of this study was to analyze the feasibility and compatibility of catfish meatballs with tempeh flour added with SNI fish meatballs as a healthy diet food for reducing dysmenorrhea in adolescents. Method: The research design applied was true experimental with 12 experimental units. The calcium content of the samples was determined using Atomic Absorption Spectrophotometry (AAS), the protein content used the Kjeldahl technique, the water content used the Oven method, and the acceptance test used the Hedonic Scale Test on adolescent. Data were analyzed using the One-Way ANOVA, and the acceptance test results were analyzed using the Friedman test with significance level α=0.05. The proportion of tempeh flour on catfish meatballs was 0% (P0), 10%, 20% and 30% (P10, P20, and P30). Results: The results showed that the adding tempeh flour could improve the levels of calcium, protein, and acceptability (taste) of catfish meatballs. The addition of 10 percent (P10) tempeh flour was an acceptable composition of the taste, but its value did not differ significantly from other recipes. Conclusion: Catfish meatballs P30 has the highest calcium and protein content. Further research is needed to fine-tune the flavor and confirm its effectiveness in reducing menstrual cramps.

Effect of Soaking and Proteolytic Microorganisms Growth on the Protein and Amino Acid Content of Jack Bean Tempeh (Canavalia ensiformis)

Soaking is an important step in making tempeh. Tempeh fermentation normally involves the natural presence of proteolytic bacteria capable of producing protease enzymes to break down peptide bonds in protein molecules. This study evaluated the protein and amino acid content of Jack bean tempeh (Canavalia ensiformis) soaked in distilled water during natural fermentation for 12, 24, 36, and 48 h. In this study, the crude proteins were determined using the Kjeldahl technique, amino acids were determined from protein hydrolysis, and proteolytic bacteria were enumerated for Total Plate Counts and further identified using Vitek 2.0 Compact System. The results showed that soaked Jack beans have higher protein and amino acid content, with sixteen essential and non-essential amino acids required for human bodies. The protein content of soaked Jack beans varied from 35% at 12 h to 32% at 24 and 36 h and 33% at 48 h. Soaking for 12 h yielded the highest amino acid concentration of 38,000 mg/kg L-glutamate, and the lowest of 14,000 mg/kg L-proline. Seven isolated bacteria showed proteolytic activity on Skim Milk Agar with a clear zone of 3.00 mm to 10.65 mm surrounding the colony. The bacteria identified were Pediococcus pentosaceus, Stenorophomonas maltophilia, Cronobacter sakazakii, and Klebsiella pneumonia ssp. In summary, Lactobacillaceae and Enterobacteriaceae were the predominant bacteria during tempeh fermentation, indicating the synergistic interaction between these microflorae during soaking conditions as part of their survival in this hostile environment.

Comparative assessment of the co-production of bioethanol and single cell proteins from Sugarcane Bagasse, Rice Husks, and cassava peels using Saccharomyces cerevisiae

This work compares various waste sources of feedstock (cassava peels, sugarcane bagasse, and rice husks) for the co-production of bioethanol and single cell protein using Saccharomyces Cerevisiae as fermentation enzyme. Sulphuric acid solution was used for the pre-treatment, dilute hydrochloric acid was used for hydrolysis, temperature, time, and pH of 131.8 °C, 1 hr, and 5.3 respectively. Sodium hydroxide (NaOH) was used to adjust the pH of the hydrolysate to neutral (6.7). The primary component of the single-cell protein was ammonia (NH3), which was quantified using Kjeldahl's technique of analysis, while the bioethanol produced was assessed using the colorimetric and colored reaction method using a spectrophotometer. Sugarcane bagasse showed the highest amount of bioethanol (36.57 %) while Rice husks and Cassava peels showed 30.97 % and 29.31 % respectively. The greatest bioethanol production (47.85 %) was achieved by combining feedstock, cassava, and sugar cane feedstocks. The percentage of single cell protein generated from individual feedstock was the highest using sugarcane bagasse (29.4 %) while a sugarcane bagasse and cassava peels combination gave the highest concentration for single cell protein (43.6 %). The study has demonstrated efficient bioethanol and single cell protein (SCP) co-production from Saccharomyces Cerevisiae using sugarcane bagasse, cassava peels, and rice husk as feedstock.

Peritoneal dialysis can maintain nitrogen balance with low Kt/V in anuric patients.

A big concern for continuous ambulatory peritoneal dialysis (CAPD) is dialysis adequacy in anuric patients. Some studies have even suggested that CAPD patients should be transferred to hemodialysis when they become anuric in order to achieve adequate dialysis. In the present study, we tried to find out whether anuric patients can maintain nitrogen balance with standard or even lower dialysis dose. This was a cross-sectional single-center study. Fifteen anuric CAPD patients were selected. Their 3-day dietary records were reviewed by a dedicated dietitian to calculate their energy, protein, and nitrogen intake (NI). Nitrogen removal (NR) from urine and dialysate was measured by Kjeldahl technique. Fluid status was evaluated by bioimpedance analysis. Subjective global nutritional assessment was used to evaluate nutritional status. Among the 15 patients, 9 males and 6 females, mean age was 63.80 (31-77) years, dialysis duration 39.76 (6-127) months, body weight 58.70±9.86kg, and height 160.20±7.93 cm. The mean dietary protein intake was 43.28 ± 7.57 g/day (0.80±0.15g/kg/d), total Kt/V was 1.59 ± 0.32 with dialysis dose of 7,904.00 ± 1,481.79 mL. However, they achieved neutral nitrogen balance (NI 6.92±1.21 g/d vs. NR 6.83 ± 1.36 g/d, N balance 0.09 ± 1.00 g/d). All of them maintained good nutritional status (SGA "A", serum albumin 39.67 ± 3.58 g/L), and no symptom of nitrogen retention (serum urea 20.49 ± 3.06 mmol/L). Meanwhile, they achieved good volume control with a slightly low total fluid removal (704.00 ± 293.21 mL/d). Our study suggested that anuric patients (even with low Kt/V) can achieve nitrogen balance and stay well-nourished with appropriate dietary protein intake.

The estimation of protein equivalents of total nitrogen in Chinese CAPD patients: an explanatory study

Objective The protein equivalent of total nitrogen appearance (PNA) formula, based on the urea nitrogen appearance (UNA), is popularly used by stable continuous ambulatory peritoneal dialysis (CAPD) patients to estimate dietary daily protein intake (DPI). However, we found that the estimated DPI was higher than that directly evaluated from the dietary records of most of our CAPD patients. Therefore, in the present study, we tried to determine possible bias in PNA estimation by UNA with a nitrogen balance study of our CAPD patients. Methods Thirty-one CAPD patients with stable clinical conditions were included. Their 3-day dietary records were reviewed by a dedicated dietitian to calculate their energy, protein, and nitrogen intake (NI). The nitrogen removal (NR) from urine and dialysate was measured by the Kjeldahl technique. Then, we calculated the proportion of urea nitrogen appearance (UNA) in total nitrogen appearance (TNA) and analyzed the possible factors that could affect this proportion. Results Among these patients, 17 males and 14 females, the mean age was 64.19 ± 12.42, and the dialysate drainage volume was 6700 (2540) ml/day. The percentage of UNA in TNA was 63.22 ± 6.66%. Compared with the other classic nitrogen balance studies in the CAPD population, the protein nitrogen and other nonurea nitrogen losses in this study were all lower. Based on these 31 nitrogen balance studies, we proposed a pair of new equations to estimate PNA by UNA. (1) PNA = 9.3 + 7.73 UNA; (2) PNA = PNPNA + TPL = 6.7 + 7.28 UNA + TPL. Conclusion Our study suggested that the PNA formula generated from previous European studies overestimated DPI in our CAPD patients.

A Comparative Study of Heavy Metals and Trace Elements Concentration in Milk Samples Consumed in Iraq

The measurements of major and trace elements in different brands of milk powder selected from the Iraqis market via the X-ray fluorescence (XRF) Technique have been studied in the present work. The result of the measurements reveals the high concentrations of sodium, phosphorus, sulfur, chlorine, potassium, calcium and magnesium. Furthermore, low concentrations of aluminum, silicon, iron, bromine, molybdenum, iodine, barium, titanium, manganese, cobalt, chrome, nickel, copper, zinc and lead were detected. Neutron activation analysis (NAA) and Kjeldahl technique were also employed to determine the concentrations of nitrogen. It was found that the nitrogen concentration was in the range of (1.96 - 3.23) % which is within the permissible limits. The concentrations of the trace elements (copper, manganese, zinc, lead) were verified via the atomic absorption spectrometer (AAS) technique. The results are compared with the authorized limit by the food and agriculture organization and the world health organization (FAO/WHO) standards.

Chemical relative dating of skeletons of the Iron Age cemetery of Tabriz on the basis of fluorine, uranium, and nitrogen content

Relative dating of archaeological bones by the measurement of fluorine, uranium, and/or nitrogen content is a well-established method, where the content of these elements in the bone structure must be determined. This research aims to study the human skeletal samples of Iron Age site of Blue Mosque in Tabriz, IRAN, on the basis of FUN relative dating method. In this way, the amount of fluorine in the selected samples was measured by UV–Vis spectrophotometry method, while the amount of uranium and nitrogen was determined by ICP-MS, and CHNS and Kjeldahl techniques, respectively. Totally, four bone samples of the skeleton from the cemetery were selected to be relatively dated. The results showed that sample no. 81.9 is the first one buried. Although the nitrogen content of this sample was the same as that of sample no. 80.6, but due to its higher concentration of fluorine and uranium compared to the other samples, it was likely the oldest sample studied at this work. While sample no. 80.6 had the lowest nitrogen content, but due to its lower levels of fluorine and uranium, it could be considered as the youngest,. Also, comparing the relative age of the two samples, no. 81.7 and no. 81.8, it can be concluded that sample no. 81.8 has spent more time under the soil. The results of this study clearly showed the necessity of applying all the three types of relative chemical dating methods (fluorine, uranium, and nitrogen dating) alongside, which is known as the FUN dating method.

Selection of forages by timor deer (cervus timorensis blainville) in menjangan island, bali

This study was conducted to determine the selection of forages plants by Timor deer (Cervus timorensis) on Menjangan Island and its relation to the availability, chemical and physical properties of feed plants. The study was conducted in July-September 2016 in savanna and monsoon forest habitats. The availability of habitat feed plants in the habitat was determined by the quadrat method, and the species of plant eaten by Timor deer was determined through the microhistological analysis of the fecal sample. The food selection index is determine by the Ivlev index. Energy contents of forages plants by bomb calorimeter apparatus, crude protein analyzed by Semi-Micro Kjeldahl technique, NDF, ADF and lignin levels refer to the method of Goering and Van Soest. Mineral content of calcium (Ca) and phosphorus (P) by using atomic absorption spectrophotometer. Determination of tannin content with Folin Denish reaction. Physical properties determine are water regain capacity and water solubility. The relationship between availability with the utilization of plants by Timor deer was analyzed with the similarity index. Multiple regression statistic to test the relationship between index selection with nutritional value factor and physical characteristic of plant species. The result showed that Timor deer selected 32 plants species of graminoids, forbs and woody plants. Feeding selection of Timor deer is strongly influenced by the availability of forage plants in habitat. The feeding selection was significantly influenced by three predictor variables i.e. positive nutritional value is crude protein and negative nutritional value were lignin and tannins. Selection of forage plant Timor deer is positively correlated with the physical properties of feed plants.

Low-dose dialysis combined with low protein intake can maintain nitrogen balance in peritoneal dialysis patients in poor economies .

Due to limited economic conditions, we tried to provide "fitted" dialysis doses instead of the doses recommended by the international guidelines to the individual patients. In the present cross-sectional study, we studied the dialysis adequacy and nutritional status of 5 peritoneal dialysis patients who had a low dialysis dose (2 bags, 4,000 mL/day). The 3-day dietary records were reviewed to calculate patients' energy, protein, and nitrogen intake (NI). The nitrogen removal (NR) from urine and dialysate was measured by Kjeldahl technique. Fecal nitrogen was estimated as 0.0155 g/kg/day. Subjective global nutritional assessment was used to evaluate the nutritional status. Among the 5 patients, 1male and 4 female, mean age was 59 (42 - 81) years, dialysis duration 43 (33 - 74) months, body weight 51.05±2.53 kg. The mean dietary protein intake was 0.66 g/kg/day, total weekly Kt/v was 1.25 (residual kidney Kt/v was 0.09), and total daily fluid removal was 699 mL. However, they achieved lower-level neutral nitrogen balance (NI 5.26±0.93 g/day vs. NR 5.33±0.81 g/day, N balance -0.07±0.60 g/day). All of them maintained good nutritional status (SGA "A") without symptoms of nitrogen retention (serum urea 22±4.18 mmol/L). Lower dialysis dose with lower daily protein intake can achieve a lower-level nitrogen balance and does not lead to malnutrition. It may be an effective approach to solve the dialysis problem for the economically week population in China, especially for people with a smaller body size with lower transport membrane. .

Transformation of Agricultural Market Waste Disposal to Biochar Soil Amendments

In Thailand, Tarad Thai is one of the biggest and significant agricultural markets. Therefore, the problems from fresh waste disposals in this area are recognized as one of environmental significant concerns. In order to manage this problem, the conversion of those possible agricultural waste disposals to biochar soil amendments is studied. In this work, some parts of agricultural fruits waste are durian peel, mangosteen rind, corncob and banana peel. In addition, waste from fresh shrimp, shrimp shell, is also studied. Those previous waste materials are processed by viapyrolysis method to form biochar. The studies of chemical compositions, such as major and some minor nutrition, are analyzed using the Kjeldahl technique, UV-Visible spectrophotometer and Inductively Coupled Plasma (ICP) spectrometer. The heat of combustion and some chemical properties are also studied. The biochar derived from corncob, per gram, dominates the highest value of the heat of combustion (75.151 Kcal). In addition, the study of biocharuses as soil amendments is studied via the growth of swamp morning glory. By comparing the data from typical soil and biochar soil amendments by t-test, it is found that the growing length and number of leafs shows tcal>tcrt which means that, for example, the use of the biochar soil amendments from agricultural market waste and shrimp shell as materials to grow the swamp morning glory displays the significance by comparing to typical soil.

Characterization of regenerated cellulose fibers antimicrobial functionalized by chitosan

Despite numerous investigations during recent decades in the field of antimicrobially treating textile fibers using chitosan, many obscurities remain regarding the adsorption/desorption behavior of chitosan and the influences of the accessible amino group content on the antimicrobial effectiveness of chitosan-treated fibers. Accordingly, the principal aim of the presented research was to evaluate different regenerated cellulose fibers regarding their abilities to provide highest antimicrobial effectiveness after chitosan treatments. Regenerated cellulose fibers such as viscose, modal and lyocell were antimicrobial functionalized by chitosan from solutions. The adsorption and desorption of the chitosan were analyzed using potentiometric titration, the spectrophotometric method with C.I. Acid orange VII, the Kjeldahl technique and polyelectrolyte titration. Mechanical properties of functionalized fibers were also checked. The antimicrobial activities of chitosan-functionalized cellulose fibers were examined, with regard to pathogen bacteria and fungi. The highest amino group content as a consequence of more intensive chitosan adsorption was found in viscose followed by modal and, finally, by lyocell. It was confirmed that those fibers with higher content of amino groups demonstrated a better reduction in pathogenic bacteria as well as pathogenic fungi. The functionalized cellulose fibers displayed potential utility in different fields of application, as exemplified by medical textiles for single use.

Feasibility study for the quantification of total protein content by multiple prompt gamma-ray analysis

Protein is an important nutrient in foods. The classical nitrogen analysis method is the Kjeldahl technique, which is time-consuming and inconvenient. As a convenient method to quantify protein content in biological samples, the feasibility of application of multiple prompt gamma-ray analysis (MPGA) to the quantification was studied. Results for protein content are reported for several reference materials and prove the method to be reliable.

On the accuracy of protein determination in large biological samples by prompt gamma neutron activation analysis

A prompt gamma neutron activation analysis (PGNAA) facility has been developed for the determination of nitrogen and thus total protein in large volume biological samples or the whole body of small animals. In the present work, the accuracy of nitrogen determination by PGNAA in phantoms of known composition as well as in four raw ground meat samples of about 1kg mass was examined. Dumas combustion and Kjeldahl techniques were also used for the assessment of nitrogen concentration in the meat samples. No statistically significant differences were found between the concentrations assessed by the three techniques. The results of this work demonstrate the applicability of PGNAA for the assessment of total protein in biological samples of 0.25–1.5kg mass, such as a meat sample or the body of small animal even in vivo with an equivalent radiation dose of about 40mSv.

Biosensors for Protein Detection: A Review

There is considerable demand for the rapid low‐cost determination of proteins, particularly in the food and beverage industry. The most widely used tests are based on colorimetric procedures in which proteins react to produce colored complexes. These methods (Lowry et al. 1951; Bradford 1976; Gornall et al. 1949; Smith et al. 1985) are dependent upon a number of factors other than absolute protein quantity, including amino acid composition, protein purity, and association state. The successful application of these methods relies on using representative calibration standards. Time‐consuming and complex methodologies such as the Kjeldahl technique and quantitative amino acid analysis procedures have been also reported. Apart from these methods, biosensors are interesting tools offering certain operational advantages over standard photometric methods, notably with respect to rapidity, ease‐of‐use, cost, simplicity, portability, and ease of mass manufacture. By appropriate recognition element selection, it is possible to detect either a particular target protein or a broad range of proteins. This review presents an overview of the different biological recognition elements and the various transduction systems that have been reported in the literature to design biosensors for protein detection. Examples are given to illustrate the different possibilities. It must be noticed that this review reports detection of proteins in solution and not proteins immobilized on membranes. Briefly, immobilized proteins can be detected by antibodies (Western blotting) or oligonucleotides such as aptamers (“Eastern blotting”) bearing reporter molecules, fluorescently labeled or radiolabeled.

Relationships between minerals in Australian brown rice

AbstractNinety samples of brown rice cv Amaroo, which has occupied over 50% of the area sown to rice in southern Australia in the last two seasons, were collected from the rice growing regions of southern Australia at the end of the 1991–1992 season. The samples were analysed for total nitrogen using the Kjeldahl technique, and for P, K, S, Mg, Ca, Na, Al, Cu, Fe, Mn, Mo and Zn using inductively coupled plasma emission spectroscopy. The analysis of concentrations of elements show that Mn concentrations in Australian rice were higher and Ca concentrations lower than typical values reported for brown rice grown in other countries. For all other elements the concentrations had a similar range to those reported for overseas rice. Highly significant correlations were found between the major nutrients P, K and Mg, and also N and S. The Mg to K ratio ranged from 1·3 to 1·6 which indicates that, if Japanese criteria are used, the taste/stickiness quality within this cultivar of Australian rice could vary from undesirable to highly desirable.

Calibration standards for composition-depth profiles of non-stoichiometric titanium nitride coatings

Five different TiNx coatings have been deposited on steel substrates by reactive magnetron sputtering. A quantitative analysis was carried out in two ways. The coatings were initially analysed by GDOS and after removing the coatings from the substrates and digesting the TiNx powder, nitrogen was quantified by the Kjeldahl technique and titanium by AAS. A comparison of the results shows that AAS and Kjeldahl results correlate very well, whereas GDOS results deviate from these two methods systematically.

Low level phosphorus supply affecting nodulation, N2 fixation and growth of cowpea (Vigna unguiculata L. Walp)

The interactive effect of low P supply (0, 10, 20 and 40 μM) and plant age on nodule number, mass and functioning (ureide analysis technique), vegetative growth and pod production were investigated in glasshouse-grown nodulated cowpea (Vigna unguiculata L.cv. Kausband) in sand culture. Compared with 40 μM P, P stress (0 μM P) or very low (10 μM P) supply markedly impaired nodulation, allantoin and amino-N concentrations and weight of N solutes in xylem exudates. Consequently, P stress reduced top growth and pod yields by 48 and 90%, respectively. N solutes in xylem exudates and total plant N assayed by Kjeldahl technique (as estimates of N2 fixation) responded similarly to P supply. However, the relative ureide index [(ureide-N/ureide N+amino-N)×100] remained constant (99%), irrespective of P supply, indicating the plants' complete dependency on symbiosis for growth, without implying that growth was markedly increased by N2 fixation. Although P concentrations in plant tops, roots and nodules increased with P supply, N concentrations in these plant tissues were unaffected by P supply. The concentrations of N and P in the nodules were 2–2 1/2 times higher than in plant tops. P application interacted strongly with plant age, with the largest P effect evidently achieved at the early podding stage. The significance and implications of these results are discussed.

Intestinal absorption of free oral hyperalimentation in the very short bowel syndrome

Ten adult ambulatory patients with the nonactive digestive disease short bowel syndrome were prospectively studied to quantitatively assess their free oral intake and their net digestive absorption of total calories, fat, protein, and carbohydrate during a 3-day period at least 6 months after a resection. The remaining portions of small bowel had a mean length of 75 cm (range, 0–200 cm); the remaining colon lengths had a mean of 67% of normal (range, 0%–100%). The experimental diets were formulated according to a home dietary inquiry. During the study period, pooled intakes and digestive losses were measured for total calories, fat, and protein using the bomb calorimetry, Van de Kamer, and Kjeldahl techniques, respectively. The ingested diet provided 58 ± 14 kcal · kg−1 · day−1 (mean ± SD) and consisted of 46% carbohydrate, 31% fat, and 23% protein. Net digestive absorption was 67% ± 12% for total calories, 79% ± 15% for carbohydrate, 52% ± 16% for fat, and 61% ± 19% for protein. The larger net digestive absorption of carbohydrate (P < 0.004) compared with fat and protein suggests salvage of colonic cholesterol in short bowel syndrome patients. It is concluded that these patients with the short bowel syndrome adapted to a hypercaloric, hyperprotein diet to compensate for increased fecal losses and that this hyperphagia does not seem to have impaired their net digestive absorption.

Rapid determination of shoot nitrogen status in rice using near infrared reflectance spectroscopy

AbstractNear infrared reflectance (NIR) spectroscopy is a rapid, cheap, simple technique which can be used to make quantitative analyses of the concentrations of nutrients in plant tissue. The application of NIR to determine nitrogen in rice was examined. The absorbance spectrum of rice (Oryza sativa L) shoot tissue was similar to that of the temperate cereal wheat even though rice tissue has a much higher silica content.A 19‐filter NIR instrument was calibrated to estimate the nitrogen content of rice shoots with between 0·8 and 3·50% N by the Kjeldahl technique. The calibration model developed used three wavelengths to account for 96% of the variation in sample Kjeldahl nitrogen concentration. This model was validated using 67 samples comprising five rice varieties grown on farms in two seasons in southern New South Wales. The standard error of prediction of the model was 0·15% N. A tissue testing service using this NIR calibration is now operational for rice crops in southern New South Wales.