ESTIMATION OF ORIGINAL GRAVITY BY REFRACTOMETER

Empirical equations have been determined so that Original Gravity, Percentage Alcohol by volume and Residual Gravity can be calculated from the Refractometer Scale Reading and Present Gravity of beer. The equations have been derived from 258 ales and lagers covering a range of Original Gravities from 32 excess degrees (circa 9°P) to 82 excess degrees (circa 20°P). Subsequent testing of the equations suggest that they are applicable to a wide range of beers. The accuracy and precision of these equations are sufficient to permit their use in normal quality control operations. The 95% confidence limits for Original Gravity, Percentage Alcohol by volume and Residual Gravity are, ±1·8 excess degrees, ±0·30 percent and ±0·45 excess degrees, respectively. A nomograph has been constructed from the equations to reduce the need for calculation.     

Selection of starters for a traditional Turkish yayik butter made from yoghurt

Butter is produced from two different materials in Turkey, cream and yoghurt. The butter produced from fresh yoghurt or ‘tulum yoghurt’ (a strained yoghurt produced from cow, goat or sheep milk) is called ‘yayik butter’ and has been traditionally produced in Turkey for centuries. In this research, we attempted to isolate and identify the natural lactic acid bacteria (LAB) of yayik butter and to select the best LAB combination for butter production. Twenty samples of yayik butter were collected from Afyon, Antalya, Isparta and Konya regions in Turkey and determined to have a mean pH of 4·78±0·33, a mean titratable acidity (lactic acid) of 0·23±0·07% and a mean NaCl of 0·55±1·22%. The mean counts of LAB (log₁₀ cfu g⁻¹) were 2·66±0·84 and 1·72±0·82 on MRS agar at 30 and 42°C, 2·44±0·93 and 1·78±0·24 on M17 agar at 30 and 42°C, and 1·64±1·196 on Sodium Azide Leuconostoc agar at 21°C, respectively. Eighty-five different LAB isolates were obtained from 20 yayik butters and identified asStreptococcus salivarius ssp. thermophilus (21·2%), Streptococcus sp. (4·7%), Lactobacillus delbrueckii ssp. bulgaricus (20%), Lactobacillus casei ssp.casei (15·3%), Lactobacillus paracasei ssp. paracasei (2·3%),Enterococcus faecium (18·8%). Leuconostoc pseudomesenteroides (Leucono-stoc mesenteroides ssp. dextranicum) (7·1%), Leuconostoc gelidum (Leuconostoc mesenteroides ssp.mesenteroides ) (4·7%) and Weissella paramesenteroides (Leuconostoc paramesenteroides) (5·9%). Combinations of S. salivarius ssp. thermophilus S51, Lb. delbrueckii ssp.bulgaricus A42, Lb. casei ssp. casei K64, Lb. paracasei ssp. paracasei A27, andLeu. pseudomesenteroides E83 were used as starter bacteria for experimental butter production from cream. Six different groups of butters were produced using different combinations of these bacteria (B, C, D and E samples), commercial culture (F sample), and without culture (A sample). Sensory evaluations showed that the experimentally produced butter sample of group B was more acceptable than the other butters. In addition, the buttermilk of sample B had lowest fact content. LAB counts of experimental butters produced with combined cultures and commercial culture were similar (6·66±1·87–6·83±0·040 and 6·81±0·13 log₁₀ cfu g⁻¹ on MRS agar, respectively).     

Nutritive Utilisation of Canned Sardine Protein in Olive Oil: The Influence of the Different Elaboration Process Stages and Storage for 6 Months and 5 Years

The true digestibility coefficient (TD), the metabolic utilisation (BV) and the net protein utilisation (NPU) of canned sardines from the same production lot have been studied in the different process stages of conservation and maturing (canned): raw (RS), precooked (PS), just canned (CS) and with 6 months (6MS) and 5 years (5YS) of storage. We find that during the process there are no significant quantitative fish protein losses. Qualitatively, the PS show the lowest digestibility values (TD, 0·90±0·02) and metabolic utility (BV, 0·55±0·08). The highest digestibility is showed for the CS (TD, 0·94±0·01) and the highest BV for the 6MS (0·65±0·07). All these values are high if they are compared with their casein controls (TD, 0·95, BV, 0·71), the 6MS have the highest NPU (0·61) and although this value decreases in the 5 years of storage (NPU, 0·56), the differences are not significant.     

Study of the nutritional value of black cumin seeds (Nigella sativaL)

The nutritional value of five samples of black cumin seeds from five different sources available in the local market were studied. The average values of the proximate analysis on dry matter basis were 216 g kg⁻¹ for crude protein, 406 g fat, 45 g ash, 84 g crude fibre and 249 g of nitrogen-free extract, whereas moisture content was 38 g kg⁻¹. The mineral and vitamin analyses showed that black cumin seeds contained iron, (105 mg kg⁻¹) copper (18 mg), zinc (60 mg) phosphorus (527 mg), calcium (1860 mg), thiamin (15·4 mg), niacin (57 mg), pyridoxine (5·0 mg) and folic acid (160 μg). The protein quality of black cumin seeds was evaluated using net protein utilisation (NPU), protein efficiency ratio (PER) and net dietary protein energy percent (NDPE %) for two samples imported from Syria and Turkey, while PER was determined for the Syrian sample only. The results indicated that the NPU standardised of Turkish black cumin seeds was significantly higher than that of Syrian type (P<0·05). The mean results (±SD) were 54·6±2·72 for the Syrian type and 63·1±3·74 for the Turkish type. The NDPE% mean results (±SD) were 5·3±0·79 and 5·6±0·26 for the Syrian and the Turkish samples, respectively. The PER adjusted value for the Syrian samples was 1·9. The results of protein quality evaluation and those of the nutrient composition suggest that black cumin is of relatively good nutritional value. © 1998 SCI.     

The vitamin C content of some kiwifruits (Actinidia chinensis planch., variety hayward)

Skin, outer pericarp, inner pericarp and core, respectively comprised 4·8, 43·7, 45·0 and 6·5% of a mean whole kiwifruit weight of 111·3 ± 1·3 g. Kiwifruit weights ranged from 99·0 to 125·3 g. Vitamin C content per 100 g edible flesh ranged from 37·8 to 53·6 mg with means of 43·7 ± 1·7 mg for total vitamin C,41·9 ± 1·5 mg for ascorbic acid (AA) and 1·7 ± 0·4 mg for dehydroascorbic acid (DHA). Vitamin C contents were found to be at least half previously reported contents, possibly due to losses during storage and transportation from New Zealand. Total vitamin C concentrations per 100 g of skin, outer pericarp, inner pericarp and core were 41·7 ± 3·1 mg, 42·9 ± 2·0 mg, 45·5 ± 2·3 mg and 42·3 ± 2·6 mg, respectively. Outer and inner pericarp contained similar concentrations of both AA with 40·7 ± 1·7 mg and 42·7 ± 2·1 mg, and DHA with 2·1 mg and 2·8 ± 0·7 mg per 100 g tissue, respectively. Skin and core contained lower concentrations of AA with 28·1 ± 2·4 mg and 31·1 ± 2·2 mg, and correspondingly higher contents of DHA with 13·5 ± 2·4 mg and 11·2 ± 1·3 mg per 100 g tissue, respectively. Whole fruit weight correlated with DHA concentration in both skin (r = ?0·644) and core (r = ?0·693).     

Analysis of various Nigerian foodstuffs for crude protein and mineral contents by neutron activation

Various Nigerian foodstuffs were analysed for crude protein and some important nutrient minerals, Ca, Fe, K and P, using the neutron activation technique. The protein content of the staple foods, cassava and its products, cocoyam, yam, rice and plantains, varies from about 1% to 12·8%, while the grains, maize, guinea corn and millet, as well as African breadfruit seeds and some popular vegetables, have a relatively high protein content. Corrections for the relevant reaction interferences in nitrogen determination were carried out. The precision of the sample analyses varied in the range ± 2·1 to ± 6·3%.     

Chemical evaluation of the effect of pest infestation on the nutritive value of cowpeas Vigna unguiculata

The effect of insect infestation of the cowpea legume Vigna unguiculata was investigated. Samples of the infested cowpeas with and without the infesting insects were analysed and compared with the uninfested cowpeas for possible variation in nutrients.Results showed increase in ash, crude protein and crude fibre content with infestation. Values for the infested samples (mg 100 g^?1) were: ash, 3·70 ± 0·01; crude protein, 27·1 ± 0·80 and crude fibre, 3·30 ± 0·64, as against 3·40 ± 0·03 (ash), 23·6 ± 0·88 (crude protein) and 1·9 ± 0·01 (crude fibre) for the uninfested samples.The amino acid pattern showed that the levels of aspartic acid, threonine, serine, alanine, cysteine and isoleucine were not much affected by the infestation. Marked reduction in level was observed for lysine, glutamic acid, glycine, valine, methionine and leucine. Only arginine showed an increase in level with infestation.All the vitamins assayed showed decreases in levels with infestation. Values per 100 g sample were 14·6 ± 0·24 μg (carotenes), 0·91 ± 0·02 mg (thiamine), 0·17 ± 0·1 mg (riboflavin) for the uninfested samples and 8·40 ± 0·02 μg (carotenes), 0·41 ± 0·02 mg (thiamine) and 0·08 ± 0·03 mg (riboflavin) for the infested cowpeas.Toxic substances such as phytic acid, oxalates and tannins were higher in the infested cowpeas than in the uninfested. Hydrocyanic acid decreased with infestation.     

Comparison of the residence time distributions of water and milk in an experimental UHT sterilizer

The residence time distributions (RTD) of water and milk in an experimental direct-heating UHT plant of the infuser type were measured at the same mean residence time using a dye tracer. Results showed that milk had a broader RTD than water, with minimum residence times of 1·0 s and 1·5 s and σ_t² values of 2·19±0·23 and 1·08±0·18, respectively. The effect of the broader RTD on the sterilization efficiency of the plant is discussed, together with possible reasons for this difference.     

HOP INDUSTRY COMMITTEE ANALYSIS OF HOPS OF THE 1984 CROP

Analytical values for α-acid content of thirteen varieties of hops from the 1984 crop are presented in relation to the district of production. For all varieties, except Yeoman, the tolerance aim of ±0·5% was achieved. The production of Yeoman has almost doubled this year and the inclusion of young hops with mature hops in some growths has led to increased within growth variation and failure of this variety, by a small margin, to remain within the limits of the tolerance aim. Apart from this, the variability of the crop compared well with previous years and the results are acceptable for commercial purposes. The sampling rates have been considered and no changes have been recommended.     

The Fatty Acid Composition in Tuna (Bonito,Euthynnus pelamis) Caught at Three Different Localities from Tropics to Temperate

The present paper describes the effect of habitat on the fatty acid composition of the lipid of bonito (Euthynnus pelamis), which was caught at three different localities, Philippine Sea (the tropical zone; seawater temperature at the fishing ground was 27·8°C), East China Sea (the subtropical zone; seawater temperature was 29·7°C), and the Pacific coast of Japan (the temperate zone; sea-water temperature was 20·3°C). The total lipids of various organs and stomach contents were extracted and their fatty acid composition analysed by gas chromatography (GC). Docosahexaenoic acid (DHA; 22: 6n-3) was the major unsaturated fatty acid in the lipid of all specimens examined from all localities. The mean DHA content accounted for more than 25% (mean±standard error: 26·0±0·6%) of the total fatty acids (TFA) in the lipids of all organs, a lipid profile markedly different from that of other fish species whose fatty acid composition is generally variable. Particularly, the mean DHA content of lipids in bonito caught in the northern sea-area sample (the temperate zone) was always high (28·4±0·7% TFA) in the lipid of every organ. Because the DHA contents of lipids of the stomach contents fluctuated between 9·9 and 31·9% TFA, bonito did not simply incorporate the fatty acid profile of the lipids of its prey fishes, but selectively accumulated the DHA. Though the mean DHA content in the lipid of all bonito from the tropical to the temperate zone was markedly higher than other marine fish species such as sardines and herrings, there was a small difference between those in the northern (28·4±0·7% TFA) and southern samples (the subtropical and tropical samples, 24·7±0·8% TFA) (P<0·05). It is suggested that the difference between them may be due to environmental effects, for example, the temperature of the seawater and the fatty acid composition of the lipids of prey organisms. © 1997 SCI.     

Acid-insoluble ash as a marker compound for use in digestibility studies with humans

The study aimed to evaluate acid-insoluble ash, in the form of added celite (a diatomaceous earth), as an indigestible marker compound for use in digestibility studies with humans. The study comprised two parts. First, the recovery of dietary acid-insoluble ash in the faeces was determined in a controlled 10-day metabolism study involving five 6-week-old male pigs receiving food consisting of ingredients commonly eaten by humans. Secondly, the faecal recovery of dietary acid-insoluble ash was determined with six adult humans following a set diet which maintained their normal levels of daily food intake for 7 days. The mean (±SE) recoveries of dietary acid-insoluble ash in the faeces of the pigs and human subjects were 90·0 (±2·24) and 92·1 (±4·59)%, respectively. The mean apparent faecal digestibility coefficients for dietary dry matter were not significantly different (P > 0·05) when determined by total faeces collection or by reference to the marker, in both species. It was concluded that celite is a potentially useful dietary marker compound for use in human digestibility studies involving collection of faeces. The marker was readily accepted by the human subjects and can be determined chemically using simple gravimetric analysis.     

In vivo and in vitro digestible fractions in forage

Faeces and the residues from the in vitro digestion of 13 forages were sequentially extracted with acid-pepsin, ethyl alcohol, hot water and diethyl ether and the quantity of the extracts was adjusted to a protein-free basis and expressed per 100 g of original forage organic matter. Undigested material inin vivo and in vitro experiments were respectively, 3·37 and 1·88 g (±0·12) for ethyl alcohol extracts, 1·13 and 1·10 g (±0·05) for hot water extracts, 0·15 and 0·12 g(±0·02) for diethyl ether extracts and 1·44 (±0·22) and 0g for 0·1 N -HCI extracts. The difference between values for in vivo and in vitro experiments was considered to represent endogenous material present in faeces.     

Large agarose-lipase beads for the hydrolysis of triglycerides

Candida cylindracea lipase could be immobilized by binding to large agarose beads or by entrapment within polyacrylamide polymer. Large agarose beads, prepared from native agarose, were preferred for their higher binding capacity and easy intact separation for reuse. The agarose-lipase complex is stable for 6 months at 4°C, maintaining 80% of its initial activity despite eight-fold re-use. Consequently, the lipase complex is recommended for semi-continuous hydrolysis of olive oil and milk fat triglycerides. The extent of total hydrolysis was 30·8 ± 1·25% for olive oil as against 23·1 ± 0·95% for milk fat.     

Biochemical and nutritional evaluation of Egreria radiata (clam), a delicacy of some riverine peasant populations in Nigeria

Proximate, mineral and amino acid analyses of the edible portion of clam (Egreria radiata), a delicacy of some riverine peasant populations in Nigeria, were carried out. The protein quality of the delicacy was also evaluated in a rat bioassay. Crude protein content was 61·0 ± 0·81%; crude fat, 19·0 ± 0·33%; carbohydrate, 1·40 ± 0·02%; crude fibre, 0·40 ± 0·00%, and ash, 17·4 ± 0·51%. Among the essential amino acids assayed, valine, with a chemical score of 37·5%, appeared to be the most limiting, as others had scores of over 55%, when compared with the essential amino acid pattern of whole hen's egg. Elemental analyses showed that, of the trace elements, clam was rich in iron, zinc and manganese, and also contained reasonable amounts of other elements. The PER, NPU, TD and BV were 2·55 ± 0·35, 65·7 ± 1·80, 85·3 ± 3·90 and 77·1 ± 3·35, respectively. These values compared reasonably well with those for whole hen's egg. The high nutritional qualities of the edible portion of clam justify its consumption and also recommend its wider use as a cheap good source of animal protein.     

REVISED SYSTEM FOR THE EVALUATION OF MALT MODIFICATION FROM THE E.B.C. FINE-COARSE EXTRACT DIFFERENCE

Since the fine-coarse extract difference measured by the E.B.C. mill is smaller than that measured by the Miag mill it has been necessary to devise a new system for the evaluation of malt modification from the fine-coarse extract difference. For this purpose, members of the E.B.C. Analysis Committee who carry out routine analyses by the E.B.C. method have made their results available and the mean and frequency distribution of the extract differences of 3671 malts have been calculated. The mean value for extract difference was 2·41%, the most frequent was 2·3% and the smallest and largest were 0·1 and 6·7%. The new system is based on the most frequent value (2·3%). Modification is described as very full when the fine-coarse extract difference is less than 1·3%, full (1·3–1·9), normal (2·0–2·6), low (2·7–3·3) and very low (over 3·3). The fine-grind extracts of the 3671 malts ranged from 71·2 to 84·7%, with a mean value of 80·3% and a most frequent value of 80·7%.     

Assessment of lectin activity in a toxic and a non-toxic variety of Jatropha curcas using latex agglutination and haemagglutination methods and inactivation of lectin by heat treatments

Lectin activity in a toxic (Cape Verde) and non-toxic (Mexico) variety of Jatropha curcas seed meal was investigated using latex agglutination and haemagglutination assays. Lectin activity expressed as reciprocal of the minimum quantity (in mg) of Jatropha meal per ml of the assay mixture which produced agglutination with the latex beads was 2·88 ± 0·57 and 1·71 ± 0·00 (mean ± SD, n = 3) for the toxic and the non-toxic varieties, respectively, which did not differ significantly (P > 0·05), while with the haemagglutination assay these values were 102 and 51, respectively, and differed significantly (P < 0·05). The lectins were inactivated by heating and moist heat was more effective than dry heat. The results suggest that lectins may not be responsible for short term toxicity caused by consumption of raw Jatropha meal. © 1998 SCI.     

Nutrient contents,rumen protein degradability and antinutritional factors in some colour- and white-flowering cultivars of Vicia faba beans

Six colour-flowering (Scirocco, Alfred, Carola, Condor, Tina and Herz Freya) and six white-flowering (Caspar, Albatros, Gloria, Tyrol, Vasco and Cresta) cultivars of Vicia faba were studied. The crude protein contents of colour- and white-flowering cultivars were 267±13·6 and 283±18·8 g kg⁻¹, respectively, which did not differ significantly at P<0·05. The levels of lipids, crude fibre, starch and ash varied from 14 to 22 g kg⁻¹, 88 to 143 g kg⁻¹, 407 to 485 g kg⁻¹ and 32 to 42 g kg⁻¹, respectively. The calculated organic matter digestibility (OMD) and metabolisable energy (ME) of the white-flowering cultivars were significantly higher (P<0·001) than those of the colour-flowering cultivars (OMD: 889·1±26·6 g kg⁻¹ vs 797·5±17·1 g kg⁻¹; ME: 13·97±0·49 vs 12·30±0·34 MJ kg⁻¹). In all cultivars, sulphur amino acids were lower than adequate concentration when compared with recommended amino acid pattern of FAO/WHO/UNO reference protein for a 2–5-year-old child. The in vitro rumen nitrogen degradability of colour-flowering cultivars was significantly lower (P<0·01) compared to that of white-flowering cultivars (71·4±9·3% vs 88·0±11·1%). Amongst colour-flowering varieties, the contents of total phenols (TP), tannins (T) and condensed tannins (CT) were highest in Alfred (28·3, 21·0 and 35·4 g kg⁻¹, respectively). The contents of TP and T were similar (about 15 and 10 g kg⁻¹, respectively) in Carola, Tina and Herz Freya, and the CT were in the order: Condor>Herz Freya>Carola. The CT were not detected in white-flowering varieties, T were virtually absent and TP were extremely low (4·0–4·9 g kg⁻¹). The activities of other antinutritional factors (white- and colour-flowering cultivars, respectively: trypsin inhibitor activity 3·05±0·34 and 1·85±0·09 mg trypsin inhibited g⁻¹; lectin 27·2±9·4 and 27·1±5·1 mg ml⁻¹ assay medium producing haemagglutination; phytate 15·0±2·7 and 16·6±2·3 g kg⁻¹) were very low. A strong negative correlation (r=-0·92, P<0·001) between tannins and in vitro rumen protein degradability was observed which suggested that tannins have adverse effect on protein degradability. Similarly negative correlations between tannin levels and metabolisable energy (r=-0·89; P<0·001) and organic matter digestibility (r=-0·89; P<0·001) were observed. The correlation coefficient between trypsin inhibitor activity and tannins was negative and highly significant (r=-0·88, P<0·001), whereas between tannins and saponins it was significantly positive (r=0·96, P<0·001). ©1997 SCI     

Nutrients in non-alcholic beverages in Nigeria

Forty-one samples of carbonated soft drinks in Nigeria have been shown, on analysis, to contain high sugar contents (mean value, 14·0%) despite the high cost of this ingredient; the Food and Drug regulations allow 9%–14%. There is a considerable divergence in the mean values of sugar for the four brands examined; 14·9%, 15·3%, 12·4% and 13·7% for the Cola, Fanta, clear drinks and fruit juice, respectively. Similar large deviations in mean values were recorded for other chemical constituents of the drinks. Ascorbic acid, for example, has an overall mean value of 12·2 mg/100 ml whereas individual samples have mean values ranging from 36·3 to 7·25 mg/100 ml. The ascorbic acid values for the fruit juice drinks fall short of expectation in all cases.     

41—THE MEASUREMENT OF THE MEAN FIBRE DIAMETER OF WOOL SAMPLES BY LIQUID-SCINTILLATION SPECTROMETRY

In wool samples labelled uniformly with ¹⁴C, there is a good correlation between the mean fibre diameter and the proportion of β-radiation absorbed within the fibres. An account is given in this paper of the calibration of a method of measuring the mean fibre diameter, based on this principle, by applying it to a set of eight standard wool tops with known mean diameters. Subsequent tests with 23 other tops showed that the mean fibre diameter of small samples (75–100 mg) could be determined with good precision, the mean 95 % confidence limits for a single measurement on one test specimen being ±0–36 μm.

A test of the sampling and uniformity of the standard tops showed that similar results, within currently accepted limits, were obtained when test specimens (75 mg) were taken from any of ten randomly chosen positions along each top.     

Aflatoxins and their Metabolites in the Tissues,Faeces and Urine from Lambs Feeding on an Aflatoxin-Contaminated Diet

Twenty-four lambs were intoxicated with 2·5 mg of aflatoxin (AF) kg^-1 in their feed for 21 days. Twelve lambs were slaughtered at day 21 and the remaining animals had an 8 day clearance period. Aflatoxins and their metabolites were detected in liver, kidneys, faeces and urine using TLC and fluorescence densitometry. During the intoxication period, the samples gave a wide range of concentrations, the lower extreme being in the liver and the kidney (0·03 μg kg^-1 of AFG₁) and the higher extreme in faeces (61·82 μg kg^-1 of AFM₁) and urine (27·84 μg litre^-1 of AFM₁). The average value of AFB₁ (1·94±0·9 μg kg^-1) was higher than AFM₁ (0·35±0·17 μg kg^-1) in the liver. In the kidney AFM₁ (5·45±4·01 μg kg^-1) was higher than AFB₁ (1·29±0·84 μg kg^-1). There were higher concentrations of AFM₁ (27·2±16·1 μg kg^-1, 7·37±6·53 μg litre^-1, respectively, of average level) in faeces and urine, than of AFB₁ (17·25±8·1 and 1·78±1·57 μg litre^-1, respectively). AFB_2a appeared in the kidney (0·05±0·03 μg kg^-1) and urine (0·35±0·25 μg litre^-1). The clearance time of AFB₁ from the faeces was less than or equal to 8 days and in all samples aflatoxin residues were still detected on the 8th day of the clearance period although in low quantities. These results suggest that aflatoxin transfer to and elimination by the liver and the renal tissue is small and that the danger to humans consuming lamb meat is also small. The examination of the faeces and urine could be useful as markers to detect lambs consuming a contaminated diet. © 1997 SCI.