Determination of nitrogen and ash contents in total herbage and botanical components of grassland systems with near infra‐red spectroscopy

Near infra‐red reflectance spectroscopy (NIRS) was used to develop calibration equations to measure nitrogen and ash contents in grassland samples. Four populations of samples were collected or prepared: total herbage, with a heterogeneous and complex botanical composition, and its botanical components (grasses, legumes and forbs). A set of samples from each population was selected to develop the specific calibration equations using three mathematical data treatments (log 1/R, first and second derivative). Six and seven wavelengths were selected by multiple regression to predict nitrogen and ash contents, respectively. Calibration equations were evaluated by comparing the values obtained by reference methods (Kjeldahl test and dry ashing measurements) with those predicted by NIRS. The three data treatments generally provided similar results as regards estimations of nitrogen contents. The correlation coefficients varied from 0.94 to 0.98, and the standard errors of prediction ranged from 1.10 to 1.49 g kg⁻¹ (total herbage), from 0.73 to 0.98 g kg⁻¹ (grasses), from 0.99 to 1.30 g kg⁻¹ (legumes) and from 0.76 to 0.80 g kg⁻¹ (forbs). The most suitable treatments to predict ash contents were log 1/R and the first derivative. The best performance was obtained for legumes, using log 1/R, with a correlation coefficient of 0.95 and a standard error of prediction of 3.54 g kg⁻¹. The calibration equations became more accurate as the components of the sets of samples became botanically simpler. Prediction accuracy was greater when the specific calibration equations for each population of samples were used. © 1999 Society of Chemical Industry     

Lipid composition of Bulgarian chokeberry,black currant and rose hip seed oils

The lipid composition of chokeberry, black currant and rose hip seeds was investigated. The seeds contain 19.3 g kg⁻¹, 22.0 g kg⁻¹ and 8.2 g kg⁻¹ glyceride oil respectively. The content of phospholipids, mainly phosphatidylcholine, phosphatidylinositol and phosphatidylethanolamine, was 2.8 g kg⁻¹, 1.3 g kg⁻¹ and 1.4 g kg⁻¹, respectively. The total amounts of sterols were 1.2 g kg⁻¹, 1.4 g kg⁻¹ and 0.4 g kg⁻¹. The main component was β-sitosterol, followed by campesterol and Δ⁵ -avenasterol. In the tocopherol fraction (55.5 mg kg⁻¹ in chokeberry oil, 249.6 mg kg⁻¹ in black currant oil and 89.4 mg kg⁻¹ in rose hip oil), α-tocopherol predominated in chokeberry oil (70.6 mg kg⁻¹). γ-Tocopherol was the main component in black currant oil (55.4 mg kg⁻¹) and rose hip oil (71.0 mg kg⁻¹). The fatty acid composition of triacylglycerols, individual phospholipids and sterol esters was also identified. In the phospholipids and sterol esters, the more saturated fatty acids, mainly palmitic, stearic, and long chain fatty acids predominated. © 1999 Society of Chemical Industry     

Fatty Acid Composition of ‘Cerrado’ Seed Oils

The seeds of 28 species from ‘cerrado’, a typical savanna ecosystem of Brazil, were analysed for total lipid contents and fatty acid distribution. The seeds of 10 species presented contents above 150 g kg⁻¹, the highest yield reaching 335 g kg⁻¹. Distribution of fatty acids based on polyunsaturated compounds seems to be rare in seed oils from ‘cerrado’: only three seed oils were found to be based on linoleic acid and none on linolenic acid. Eight seed oils, four of them Fabales, presented palmitic acid as a dominant constituent. Half of the species presented oleic acid based seed oils. Two species stand out for unusual fatty acid distribution: Qualea grandiflora (Vochysiaceae) with 171 g kg⁻¹ of seed oil presenting 723 g kg⁻¹ of lauric acid and Serjania erecta (Sapindaceae) with 256 g kg⁻¹ of seed oil presenting 623 g kg⁻¹ of eicosenoic acid.     

Saturated Sterols (Stanols) in Unhydrogenated and Hydrogenated Edible Vegetable Oils and in Cereal Lipids*

The content of saturated sterols (stanols) was investigated in a small number of samples of hydrogenated fats and oils, and in the ‘free’ and ‘bound’ lipids of various samples of cereals. The sterols, after saponification of the total lipids, were analysed as trimethylsilyl derivatives by GC and identified by GC–MS. Among the hydrogenated fats and oils, coconut oil contained the largest amounts of sitostanol followed by soybean oil (c 80 and 20 g kg⁻¹ of total unsaponifiables, respectively). No sitostanol could be detected in hydrogenated palm oil under the present analytical conditions. Both ‘free’ and ‘bound’ lipids in various samples of wheat, except for wheat germ, contained c 70–120 g kg⁻¹ campestanol and 100–150 g kg⁻¹ sitostanol in total unsaponifiables. In lipids of oats and barley, no campestanol or sitostanol could be detected. Rye total lipids contained 60–90 g kg⁻¹ of campestanol and 100–150 g kg⁻¹ of sitostanol of total unsaponifiables in ‘free’ and ‘bound’ lipids, respectively.     

Resistant starch production from mango starch using a single‐screw extruder

Resistant starches were prepared from mango starch by extrusion. An experimental design with independent variables temperature, screw speed and moisture content produced 20 samples that were studied to determine the effect of these variables on resistant starch (RS) content, water absorption index (WAI) and water solubility index (WSI). RS content was affected by moisture content and temperature. Screw speed and temperature also influenced RS content, the highest level (97 g kg⁻¹) being obtained at low screw speed and high temperature, this pattern can be associated with a longer residence time, which gives rise to more opportunity for amylose chain association. The regression model fitted to the RS experimental results showed a good correlation coefficient (0.80). When moisture content and temperature decreased, WAI increased (105–142 g kg⁻¹), but low WAI values (70–77 g kg⁻¹) were obtained at moisture contents between 200 and 300 g kg⁻¹ and high temperatures (140–150 °C). When moisture content and temperature increased, WSI increased (222–332 g kg⁻¹), but at high temperature value (120 °C) assayed and the lowest moisture content (150 g kg⁻¹), WSI also increased. In the range of moisture contents tested and at low temperatures, only partial gelatinisation occurred and low solubility was obtained. Copyright © 2005 Society of Chemical Industry     

DETERMINATION OF FERMENTABLE SUGARS AND NITROGENOUS COMPOUNDS IN WORT BY NEAR- AND MID-INFRARED SPECTROSCOPY

Near-infrared (NIR) and mid-infrared (MIR) spectroscopy techniques were evaluated for the analysis of brewery worts. Good calibrations were obtained for maltose (SEP_NIR 2.6 g/l, SEP_MIR 2.0 g/l), glucose SEP_NIR 0.6 g/l, SEP_MIR 0.4 g/l) and the sum of fermentable sugars (SEP_NIR 2.8 g/l, SEP_MIR 2.6 g/l) with both methods. Satisfactory calibration was obtained for maltotriose (SEP_NIR 1.4 g/l, SEP_MIR 1.5 g/l), nitrogen (SEP_NIR 122 mg/l, SEP_MIR 92 mg/l) and free alpha-amino nitrogen (SEP_NIR 29 mg/l, SEP_MIR 23 mg/l). MIR spectroscopy gave slightly better results, but sample handling was more difficult than in the NIR region. The NIR measurement is simple and rapid and could be used for on-line process control during mashing. No sample preparation other than filtration is needed.     

Effect of fish,starch and salt contents on the microstructure and expansion of fish crackers (‘keropok’)

Light microscopy studies on the fish cracker gel and expanded product (‘keropok’) emphasised the role of fish proteins in the starch expansion process. The addition of salt (20 g kg⁻¹) in the ‘keropok’ helped to distribute evenly the starch in the fish protein. Formation of thin fish muscle bundles assisted the expansion of ‘keropok’. At 700–900 g kg⁻¹ fish content, the fish muscle bundles formed a continuous network that caused a drop in the ‘keropok’ expansion. From the scanning electron microscopy study, ridges were found in samples (containing 600–900 g kg⁻¹ fish content) with 20 g kg⁻¹ salt at high magnification. © 1999 Society of Chemical Industry     

Influence of skimmed milk concentrate replacement by dry dairy products in a low‐fat set‐type yoghurt model system. Use of caseinates,co‐precipitate and blended dairy powders

Yoghurt fortification with caseinates, co‐precipitate and blended dairy powders in a low‐fat yoghurt model system was studied. These dairy products were characterised for pH, moisture, lactose, mineral and protein fractions. Milk proteins were characterised by polyacrylamide gel electrophoresis (SDS‐PAGE) and isoelectric focusing (IEF). Minerals such as Na, Ca, K and Mg were analysed by atomic absorption spectroscopy. Yoghurts were formulated using a skimmed milk concentrate as a milk base enriched with different dry dairy products up to 43 g kg⁻¹ protein content. The percentage of skimmed milk concentrate replaced with dry dairy products in the mix was between 1.37 and 6.35%. Yoghurts enriched with caseinates had higher viscosity and syneresis index (56.81 Pa s and 548.8 g kg⁻¹ respectively) than yoghurts based on concentrated skimmed milk fortified with co‐precipitate (39.00 Pa s and 392.9 g kg⁻¹) or blended dairy products (33.25 Pa s and 431.8 g kg⁻¹). One blended dairy product was tested to manufacture low‐fat yoghurt on an industrial scale, yielding good rheological properties (high viscosity‐consistence, 37.77 Pa s, and low syneresis index, 450 g kg⁻¹) and lower cost than traditional enrichment with skimmed milk powder. © 2000 Society of Chemical Industry     

The potential of NIR spectroscopy for the detection of the adulteration of orange juice

Near-infrared spectroscopy was used to investigate the adulteration of 65 authentic concentrated orange juice samples obtained from Brazil and Israel. These samples were adulterated with 100 g kg^?1 additions (ie 100 g added to 900 g) of (1) orange pulpwash, (2) grapefruit juice, and (3) a synthetic sugar/acid mixture and with 50 g kg^?1 additions (ie 50 g added to 950 g) of (4) orange pulpwash, and (5) grapefruit juice. All samples were scanned on the NIR systems 6500 spectrophotometer over the 1100-2498 nm wavelength range. Principal component analysis was used to reduce each spectrum to 20 principal components. Factorial discriminant analysis was used to distinguish between the different sample groups. Using orange juice and orange juice adulterated at the 100 g kg^?1 level, accurate classification rates of 94–95% were obtained. To classify samples adulterated at the 50 g kg^?1 level, the calibration development sample set had to be augmented by the inclusion of samples adulterated at this lower level—after this augmentation, an accurate classification rate of 94% was obtained. The results demonstrated that the application of principal component and factorial discriminate analysis to NIR reflectance spectra can detect the adulteration of orange juice with an average accuracy of 90%. Furthermore, not one adulterated sample was predicted as being an authentic orange juice throughout the entire test regime.     

Removing τ‐fluvalinate residues from press‐extracted honey

Honey is obtained from the hives of European honeybees. Honeybees can be infested by Varroa parasitism, which affects honey production. The acaricide τ‐fluvalinate used in beehives to control Varroa mites, can leave its residues in honey, pollen and wax. A monitoring study was undertaken to determine the τ‐fluvalinate residues in honey samples taken from treated hives. The τ‐fluvalinate residues were determined by gas chromatography using a short, non‐polar packed column with electron capture detection. Analysis of 50 samples showed an average residue level of 15 µg kg⁻¹. The same samples were filtered through Whatman filter paper to separate the honey from residual suspended particles. The filtered honeys showed no acaricide residues above the detection limit of 3 µg kg ⁻¹, while the average residue level determined in the sediments was 392 µg kg ⁻¹. Thus the residues of τ‐fluvalinate in honey can be eliminated by separating the honey from residual suspended particles that contain acaricide residues. Copyright © 2003 Society of Chemical Industry     

Aframomum stipulatum (Gagnep) K. Schum and Aframomum giganteum (Oliv. & Hanb) K. Schum as Aroma Tincto Oleo Crops resources: essential oil,fatty acids,sterols, tocopherols,and tocotrienols composition of different fruit parts of Congo varieties

BACKGROUND: Today, few known plant species provide both an essential oil (EO) and a vegetable oil (VO). Seed and husk of two Aframomum species were investigated and compared in terms of EO, fatty acids, tocopherols, and tocotrienols. RESULTS: EO yield reaches 15.3 g kg⁻¹ in the seeds and 3.2 g kg⁻¹ in the husks, while VO yield is 180.0 g kg⁻¹ in the seeds and 25.0 g kg⁻¹ in the husks. β‐Pinene, 1,8‐cineol, α‐selinene, terpine‐4‐ol, linalool, myrtenal and β‐caryophyllene are the major compounds of seed and husk EO. Fatty acid analysis of two Aframomum species shows that oleic, linoleic, and palmitic acids were the major compounds of VO. Total sterol contents reached 4.3 g kg⁻¹ in seed VO and 8.5 g kg⁻¹ in husk VO. An appreciable amount of tocopherols (0.52 g kg⁻¹) was found in seed VO. CONCLUSION: The seed and husk oil of A. stipulatum and A. giganteum fruits are rich sources of many bioactive constituents such as fatty acids, sterols, tocopherols and tocotrienols. These tropical wild fruits can be considered as new Aroma Tincto Oleo Crops (ATOC) resources that contain both EOs and VOs. Copyright © 2012 Society of Chemical Industry     

Supplementary α‐tocopherol acetate in full‐fat rapeseed‐based diets for pigs: effect on performance,plasma enzymes and meat drip loss

Twenty‐four Large White × Landrace pigs were individually fed, from 50 to 90 kg live weight, either a control (CONT) diet containing palm oil or one of three diets based on full‐fat rapeseed (250 g kg⁻¹) (diets RD). The RD diets were supplemented with 0, 200 or 500 mg DL ‐α‐tocopherol acetate (ATA) kg⁻¹ diet (diets RD0, RD200 and RD500 respectively). Diets were formulated to be isonitrogenous and isocaloric. Daily live weight gain was significantly increased (p < 0.01) in pigs fed diet RD500. Plasma AT concentration was significantly increased by dietary supplementation with 200 mg ATA kg⁻¹ but showed no further significant increase by supplementation with 500 mg ATA kg⁻¹. At slaughter, after 45 days, carcass weights were increased for the RD500 group but dressing percentage was unaffected. ATA supplementation significantly reduced drip loss on days 4 and 5–7 in fresh muscle and on days 1 and 4 in frozen muscle. The concentrations of calcium, sodium and potassium in drip loss fluid collected on days 1 and 4 from fresh muscle were not significantly affected by treatment or by time of collection and did not suggest any change in the relative contribution of intra‐ and extracellular fluid to total drip loss. Plasma enzyme activities related to tissue damage (creatine kinase, alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase) were not influenced by dietary treatments. © 2000 Society of Chemical Industry     

Non-destructive determination of fat,moisture and protein in salmon fillets by use of near-infrared diffuse spectroscopy

Near infrared (NIR) diffuse spectroscopy was used to determine the fat, moisture and protein contents in whole and ground farmed atlantic salmon fillets. A remote fibre-optic probe was used for NIR measurements on 50 whole salmon fillets. The constituent ranges were: 91-205 g kg^?1 fat, 599-709g kg^?1 moisture and 186-209 g kg^?1 protein. Principal component regression resulted in the following prediction errors for ground salmon fillets, expressed as root mean square error of cross validation: 6.6 g kg-1 fat, 3.8 g kg^?1 moisture and 2.0 g kg^?1 protein. The corresponding prediction errors for non-destructive measurements on whole salmon fillets were 10.8 g kg^?1 fat, 8.5 g kg^?1 moisture and 3.7 g kg^?1 protein. Regression models using the 760-1100 m range gave lower prediction errors than models using the 1100-2500 mm or 760-2500 nm ranges. The results show that fibre-optic probe NIR instruments are suited to determine fat and moisture in whole salmon fillets non-destructively.     

The occurrence and prevention of ethanol fermentation in high‐dry‐matter grass silage

Ethanol is a common, usually minor fermentation product in ensiled forages, the major product being lactic acid. Occasionally, high levels of ethanol are found in silages. The aim of this study was to determine the incidence of high‐dry‐matter (DM) grass silages containing ethanol as the main fermentation product (ethanol silages), to describe the fermentation process in such silages and to determine the effect of grass maceration prior to wilting and addition of a bacterial inoculant containing Lactobacillus plantarum and Enterococcus faecium strains on fermentation. Twenty‐one laboratory silages produced between 1993 and 1995, 21 farm silages produced between 1980 and 1989 and 36 farm silages produced in 1995 (all produced without additive) were examined for pH and chemical composition. Dry matter (DM) loss during ensilage was determined for the laboratory silages only. Four laboratory silages were identified as ethanol silages. Mean concentrations of ethanol, lactic acid and acetic acid were 48.1, 15.5 and 6.0 g kg⁻¹ DM respectively. In the silages that contained lactic acid as the main fermentation product (lactic acid silages) these values were 7.7, 45.5 and 15.1 g kg⁻¹ DM. Mean DM loss and pH were 62.8 g kg⁻¹ DM and 5.32 respectively for ethanol silages and 24.4 g kg⁻¹ DM and 4.69 for lactic acid silages. There was no difference between ethanol silages and lactic acid silages in the mean concentration of ammonia‐N (94 g kg⁻¹ total N), and butyric acid was not detected (<0.2 g kg⁻¹ DM), indicating that both types of silages were well preserved. Analysis of the composition of the grass at ensiling showed a positive correlation between the concentration of soluble carbohydrates and the development into ethanol silage. Analysis of the farm silages indicated that 29% of the silages produced between 1980 and 1989 and 14% of those produced in 1995 were ethanol silages. Maceration prior to wilting and addition of silage inoculant improved lactic acid fermentation and prevented high ethanol levels. The micro‐organisms responsible for ethanol fermentation as well as the implications of feeding ethanol silages to livestock remain to be resolved. © 2000 Society of Chemical Industry     

Monitoring of seed composition of prickly pear (Opuntia ficus‐indica L) fruits during maturation period

Prickly pear fruit seeds were subjected to a range of chemical analyses during their 15 week maturation period. Seeds contained on average 71.5 g kg^?1 dry matter, 61.9 g kg^?1 crude oil, 9.4 g kg^?1 protein, 507.4 g kg^?1 crude fibre, 12.3 g kg^?1 ash and 409.0 g kg^?1 carbohydrate. The fatty acid composition of prickly pear seed oil consisted of 1.3–1.9 g kg^?1 myristic (14:0), 132.1–156.0 g kg^?1 palmitic (16:0), 14.4–18.5 g kg^?1 palmitoleic (16:1), 33.1–47.9 g kg^?1 stearic (18:0), 210.5–256.0 g kg^?1 oleic (18:1), 522.5–577.6 g kg^?1 linoleic (18:2), 2.9–9.7 g kg^?1 linolenic (18:3), 4.2–6.6 g kg^?1 arachidic (20:0) and 2.1–3.0 g kg^?1 behenic (22:0) acids, which is comparable with that of corn oil. No statistical difference in seed weight ratio was determined during the maturation period, whereas changes in the saturated fatty acids of the seed oil were observed. From this study it can be concluded that the seeds of prickly pear are suitable as animal feed. Copyright © 2003 Society of Chemical Industry     

Low‐protein amino acid‐supplemented diets in broiler chickens: effects on performance,carcass characteristics,whole‐body composition and efficiencies of nutrient utilisation

Two concurrent trials were conducted to investigate the influence of low‐protein amino acid‐supplemented diets on the performance, carcass characteristics, whole‐body composition and efficiencies of nutrient utilisation by the male broiler chicken from age 3 to 6 weeks. The first trial comprised five isoenergetic (13.0 MJ kg⁻¹) diets containing 225 (control), 210, 190, 172 or 153 g kg⁻¹ crude protein (CP) supplemented with essential amino acids (EAAs) to meet the minimum National Research Council recommendations. In the second trial a composite mixture of non‐essential amino acids (NEAAs) was added to the lower‐CP diets (ie 210–153 g kg⁻¹) such that they became isoproteinous (N × 6.25) with the 225 g kg⁻¹ control. Neither the lowering of dietary CP nor NEAA supplementation had any significant influence on weight gain or the relative weights of the various carcass cuts. However, chicks fed the lowest‐CP diets consumed more feed (P ≤ 0.05) and had poorer (P ≤ 0.05) feed conversion efficiency (FCE). NEAA supplementation enhanced FCE to the control levels. Whole‐body compositional analysis showed that lowering dietary CP increased (P ≤ 0.01) total body fat in a linear fashion (P ≤ 0.001; r = −0.72). Equalising dietary CP with the control (ie maintaining identical energy/protein ratio) by NEAA supplementation did not correct for the fat deposition. Total body protein (g kg⁻¹) was identical with the control with or without NEAA supplementation. Dietary energy, protein retention efficiency (PRE) and protein efficiency ratio (PER) were more efficient (P ≤ 0.01) in the lower‐protein diets, while NEAA supplementation significantly (P ≤ 0.01) decreased the efficiency of N utilisation. Reducing dietary CP from 225 to 153 g kg⁻¹ decreased N excretion in a highly significant linear fashion (P ≤ 0.001; r = 0.73). The nutritional and environmental implications of the increased body fat deposition on the one hand and the decreased N excretion on the other in the low‐protein‐fed chickens are discussed and the need to harmonise these apparently conflicting interests is emphasised. © 2000 Society of Chemical Industry     

Influence of skimmed milk concentrate replacement by dry dairy products in a low fat set‐type yoghurt model system. I: Use of whey protein concentrates,milk protein concentrates and skimmed milk powder

Ten commercial samples of dry dairy products used for protein fortification in a low fat yoghurt model system at industrial scale were studied. The products employed were whey protein concentratres, milk protein concentrates, skimmed milk concentrates and skimmed milk powder which originated from different countries. The gross chemical composition of these dried products were determined, including polyacrylamide gel electrophoresis (SDS‐PAGE) and isoelectric focusing of the proteins, and minerals such as Na, Ca, K and Mg. Yoghurts were formulated using a skim milk concentrated as a milk base enriched with different dry dairy products up to a 43 g kg⁻¹ protein content. Replacement percentage of skim milk concentrated by dry dairy products in the mix was between 1.49 and 3.77%. Yoghurts enriched with milk protein concentrates did not show significantly different viscosity (35.12 Pa s) and syneresis index (591.4 g kg⁻¹) than the two control yoghurts obtained only from skimmed milk concentrates (35.6 Pa s and 565.7 g kg⁻¹) and skimmed milk powder (32.77 Pa s and 551.5 g kg⁻¹), respectively. Yoghurt fortified with the whey protein concentrates, however, was less firm (22.59 Pa s) and had less syneresis index (216 g kg⁻¹) than control yoghurts. Therefore, whey protein concentrates may be useful for drinking yoghurt production. © 1999 Society of Chemical Industry     

Wet Milling Comparison of Quality Protein Maize and Normal Maize

Quality protein maize (QPM) experimental hybrids and normal maize possessing different physical and chemical properties were studied as the raw material for wet milling. Maize samples were steeped for 36 h in a 600-ml solution containing 15 g kg⁻¹ lactic acid and 0·5 g kg⁻¹ SO₂ followed by 12 h in a second 600-ml solution containing 5 g kg⁻¹ lactic acid and 1 g kg⁻¹ SO₂. The steeped grain was then wet milled and the yields and purity of fractions were analysed. Water-soluble solids, kernel size, quality protein, total dietary fibre and ash content were higher in QPM samples than in normal maize. Water-soluble solids were positively correlated to kernel size ( r =0·97, P< 0·05), test weight ( r =0·83, P< 0·05) and density ( r =0·57, P< 0·05). Total fraction recovery for the five hybrids tested ranged from 921 to 955 g kg⁻¹, with the highest values corresponding to QPM hybrids. QPM hybrids yielded slightly higher starch content than normal maize. Gluten yields of QPM-HO (high oil) presented the highest values. The lysine contents of kernel, gluten and milling solubles were highest for QPM hybrids. QPM contained more palmitic acid than the other hybrids. The H-137 normal maize and QPM yellow dent-HO contained more oleic and linolenic acids than the other samples, and the QPM white-C (corneous) contained more linoleic acid than QPM-HO and normal maize.     

Determination of Chlorogenic Acids with Lactones in Roasted Coffee

An HPLC method has been developed which allowed the determination of mono- and dicaffeoylquinic acids (CQA and di-CQA), corresponding lactones (CQL) and feruloylquinic acids (FQA) in roasted coffee within one chromatographic run. The elution order was verified by isolation of the individual compounds by preparative HPLC, chromatography of the fractions on the analytical HPLC system, NMR spectroscopy and thermospray LC-MS. At least 15 additional minor compounds had the spectra of hydroxycinnamic acids, some of them only occurring in roasted coffee. Caffeoyltryptophan, which has been identified some time ago by another working group could also be separated with this system. The average contents in commercial roasted coffee samples (n=12) were: 3-CQA, 5·0 g kg⁻¹; 4-CQA, 6·2 g kg⁻¹; 5-CQA, 11·4 g kg⁻¹; 4-FQA, 0·7 g kg⁻¹; 5-FQA, 1·4 g kg⁻¹; 3-CQL, 2·1 g kg⁻¹; 4-CQL, 1·0 g kg⁻¹; 3,4-di-CQA, 0·7 g kg⁻¹; 3,5-di-CQA, 0·4 g kg⁻¹ and 4,5-di-CQA, 0·8 g kg⁻¹ dry matter. There were only small differences between the different brands. Two series of samples with different degrees of roast produced from the same green coffee have also been analysed. One series was steam treated before roasting (a process which is commercially used to improve digestibility). Only in the initial stages of roasting (light roast) could a difference in the contents of the acids between both series be observed. Keeping coffee brews at an elevated temperature (4 h at 80°C) reduced the amounts of CQL to 60% of the initial value. The contents of 3-CQA and 4-CQA increased, whilst that of 5-CQA decreased. The overall contents of CQA decreased.     

Nutritional and physicochemical evaluations of tahina (sesame butter) prepared from heat‐treated sesame seeds

Dehulled sesame seeds were roasted using different heat treatments. The effects of roasting treatments on the nutritive value, physicochemical properties and sensory properties of produced tahina were studied. Resultant tahina contained 586–594 g kg⁻¹ crude oil, 219–226 g kg⁻¹ crude protein and <30 g kg⁻¹ crude fibre and ash. Crude protein, crude fibre, ash and N‐free extract in tahina samples were not affected by roasting treatments. However, crude oil was decreased by steam roasting and hot plate roasting. Hot plate roasting was more effective in reducing raffinose content than other roasting treatments, whereas vacuum roasting was less effective in reducing raffinose content than other roasting treatments. Tahinas were good sources of essential amino acids, especially sulphur‐containing amino acids, aromatic amino acids and tryptophan. Hot air roasted tahina followed by vacuum roasted tahina had higher total essential amino acid contents than steam roasted and hot plate roasted tahinas. Lysine was the first limiting amino acid in tahinas. Tahinas had a relatively high in vitro protein digestibility (over 83%). Tahina is a good source of niacin. Hot air roasted tahina had the highest content of B group vitamins compared with other tahina samples. Resultant tahinas had relatively high amounts of Na, Mg, K, Cu, Zn and Fe and a low amount of Ca. Roasting treatments did not affect the mineral contents. All roasted samples had a typical protein spectrum with a maximum absorption at 280 nm and minimum at 260 nm. However, the spectrum of hot air roasted tahina proteins was sharper than the spectra of other tahina proteins. Size exclusion HPLC fractionated tahina proteins into two fractions for hot roasted and vacuum roasted tahinas and three fractions for steam roasted and hot plate roasted tahinas. The gel filtration pattern of tahina proteins contained four peaks with identical elution volumes but different proportions. Hot air roasted and vacuum roasted tahinas had higher panel scores than steam roasted and hot plate roasted tahinas for all tested sensory properties. © 2000 Society of Chemical Industry