Ergogenic Attributes of Young and Mature Coconut (Cocos nucifera L.) Water Based on Physical Properties,Sugars and Electrolytes Contents

The present work aimed to compare the main ergogenic attributes of two commercialized stages (young and mature) of coconut water (CW) obtained from four coconut varieties. The changes of electrolytes and sugars in CW upon maturation were quantified by inductively coupled plasma mass spectrophotometer and high-performance liquid chromatography, respectively. Based on the electrolyte profiling, potassium yielded the highest amount (ranging from 237.41 to 361.20 mg/100 mL) followed by sodium, magnesium, calcium, iron, manganese, copper, selenium, and zinc across all the maturity stages tested. For sugars, there were lower amounts of fructose and glucose, but a higher amount of sucrose with the maturation of the fruits. In conclusion, the amount of beneficial nutrients in the form of sugars and minerals was higher than that of young CW, and the ergogenic attributes of mature CW especially from MATAG variety (M-MATAG) were the best to be exploited further in the development of natural energy drinks.     

Proximate composition and amino acid and mineral contents of Mormordica charantia L. pericarp and seeds at different maturity stages

The three maturity stages found in the pericarp and seeds of bitter melon (Momordica charantia) were investigated for their variations in proximate composition, amino acid profiles, and mineral contents. Moisture, starch, and total dietary fibre contents of pericarp, from all maturity stages (immature, mature and ripe), were significantly higher (P value <0.05) than those of ripe and mature seeds, while lipid and protein contents of seeds were statistically higher (P value <0.05) than those of pericarp. Maturity did not change the lipid content of the pericarp, while maturity progression decreased the protein content of bitter melon pericarp. A significant increase in the protein (30.4%) and lipid (37.6%) contents was observed in bitter melon seeds as the maturity progressed. Ripe seeds that have more than 30% protein could be a good protein source for functional ingredients in a food system. Bitter melon can be considered a good source of these nutrients.     

Development of a UV coupled indigenous hydrophilized polyamide membrane system for enhanced shelf life of mature coconut water

The demand for mature coconut water is growing tremendously in beverage industries due to its high salubrious value and potential healing properties. Many coconut processing industries that manufacture products such as coconut oil, coconut milk, and desiccated coconut generate a massive volume of unutilized mature coconut water. Thus, the discharged liquid waste of valuable food products causes severe environmental pollution. Therefore, there is a need to develop a strategy to treat the unused liquid discharge that can improve shelf-life, natural freshness, flavor, aroma, and recovery of value-added products. In the present investigation, mature coconut water (CW) was concentrated by a UV coupled hydrophilized polyamide (HPA) reverse osmosis (RO) membrane. Experiments were conducted by varying functional parameters like applied pressure and operating time on flux, percentage water recovery, and salt rejection. From experimental observations, the membrane was found to exhibit 62.50% water recovery and 86.35% salt rejection with a maximum water flux of 4.85 L/m².h at an optimized feed pressure of 8 kg /cm². Further research was carried out by passing the concentrate solution through a UV module at 254 nm to prevent bacterial contamination. Additionally, the physicochemical parameters were assessed, and sensory evaluation studies were conducted to explore the final product's properties. The concentrate and permeate CW shelf-life was enhanced from 2 h to 30 days by refrigerating the samples at 4°C. Finally, the cost estimation of the designed system is provided to verify process scale-up and commercialization feasibility.     

Effects of harvest time and storage on dietary fibre components in various cultivars of white cabbage (Brassica oleracea var capitata)

The effect of harvest time and storage on dietary fibre content and composition was investigated in six cultivars of white cabbage (Brassica oleracea var capitata). Three cultivars were of early maturity type (SW Nordpol, Rolly and Balbro) and three of late maturity type (Predikant, Hanna and Lion). The average total dietary fibre (TDF) content was 241 g kg^?1 dry matter (DM) (CV = 13), of which approximately 25% was soluble (CV = 15). The main dietary fibre components were glucose (37%), uronic acid (32%), arabinose (12%) and galactose (8%) residues. Early cultivars generally had a lower TDF content than late maturity types, due to a lower amount of both insoluble (arabinose, galactose and glucose) and soluble (arabinose) polymers. An early cultivar, Rolly, had the highest solubility, 33%, versus 25 ± 4% for the other cultivars. The early cultivar SW Nordpol had a similar TDF content and proportion of soluble dietary fibre (SDF) to the late cultivar Hanna, but the dietary fibre composition was different, with the early cultivar having a lower proportion of arabinose residues. Storage for 6 weeks had minor effects on the dietary fibre. After further storage of the late maturity cultivars, there was an increase in insoluble dietary fibre (IDF) (glucose and uronic acid residues) and a decrease in SDF (arabinose and galactose residues). As a consequence the solubility of TDF decreased from 29 to 19% on average. Harvesting before physiological maturity was reached resulted in a somewhat lower content of TDF and IDF for two cultivars (Predikant and Hanna), while SDF was more or less unaffected for all cultivars. Long‐term storage had fewer effects on cabbage harvested prior to maturity than when harvested at the right physiological maturity. It is concluded that the observed differences between cultivars and after long term storage are of such magnitude that they may affect nutritional properties of the dietary fibre. © 2002 Society of Chemical Industry     

SEASONAL VARIATIONS IN FATTY ACID COMPOSITION OF OIL IN DEVELOPING COCONUT

ABSTRACT

Studies on seasonal variation in oil and fatty acid profile of developing solid endosperm of two cultivars, West Coast Tall (WCT) and Chowghat Orange Dwarf (COD), and their hybrids indicated that oil percentage increased from 30% in 6‐month‐old nuts to 63% in matured nuts (12 months old). Nuts sampled during July from different levels of maturity had high oil percentage and followed by those sampled during April, October and January. During nut development to maturity, the percentages and contents of medium and long chain saturated fatty acids increased except that of palmitic and myristic acids. Concentration of long chain unsaturated fatty acids (LCUFAs) in developing coconut kernel were high at 5 and 6 months after fertilization and then decreased toward maturity. The LCUFAs were high in nuts developing during October; consequently, saturated to unsaturated fatty acid ratios were low during October. Results indicated that nuts matured during October had better nutritional quality for human consumption and those matured during January are more suitable for industrial purpose due to higher medium chain fatty acid concentrations.

PRACTICAL APPLICATIONS

Coconut is consumed either as the tender nut (5–6 months after fertilization) or as the kernel from mature nut (12 months after fertilization). Recent technologies of making snowball tender nut use the nuts aged 7–8 months old. Kernel also is consumed in this product. Apart from this, the coconut is being increasingly used for making different kernel‐based value‐added products. This information is useful, as the value‐added products are being developed using different maturities of coconut. Hence, it is of paramount importance that the fatty acid profile of coconut kernel is known in detail for assessing the safety of food consumption from the human health point of view. Apart from this, information on the seasonal variation in fatty acid profile of developing endosperm gives an integrated knowledge so as to optimize the usage of coconut kernel for both human consumption and industrial exploitation.

     

Lignin Impact on Fibre Degradation: 1—Quinone Methide Intermediates Formedfrom Lignin DuringIn VitroFermentation ofCorn Stover*

Experiments were conducted to determine whether formation of quinone methide intermediates from lignin occurs during ruminal fermentation of corn stover, as indicated by nucleophilic addition reaction with sulphur-containing reducing agents. Corn stover leaf and stem fractions harvested at full maturity were incubated in buffered ruminal fluid without reducing agents or with (NH₄)₂SO₄ (S-control), Na₂S.9H₂O, cysteine-HCl (cysHCl), or cysHCl plus Na₂S.9H₂O; and in only buffer with or without cysHCl plus Na₂S.9H₂O. Mixed reducing agents (cysHCl plus Na₂S.9H₂O) enhanced ( P< 0.001) in vitro fibre degradation after 48 h, tended to increase solubilisation of fibre ( P =0.07) and dry matter ( P =0.06) in buffer alone, and elevated ( P< 0.001) S-content of residual fibre. In vitro incorporation of S into the undegraded fibre was determined for corn stover fractions of varying lignin compositions that were harvested at two maturities (early dent and full maturity) in 2 years. Extent of fibre degradation was correlated with extent of S-incorporation ( r =-0.54, P< 0.001), and with lignin methoxyl content ( r =-0.84, P< 0.001). The negative association of lignin methoxyl content with digestibility is explained by the relative likelihood of quinone methide intermediate formation from guaiacyl and syringyl units in lignin.     

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.     

Chemical composition and in vitro degradability of major chemical constituents in botanical fractions of red clover harvested at different stages of maturity

Red clover was harvested at five different stages of maturity during primary growth and separated into leaves, petioles, stems and flowers. The contents of extractives, crude protein, starch, non-starch polysaccharides, and non-starch polysaccharide constituents, and the in vitro degradability, were determined in the botanical fractions. Chemical analysis of the in vitro residues revealed that the degradability of crude protein was around 80% in all fractions at all harvest times whereas in most cases the degradability of non-starch polysaccharides and non-starch polysaccharide residues was highest in the leaf fractions, intermediate in the petiole fractions and lowest in the stem fractions, with only small changes occurring due to development and maturation during the investigated period. Glucose and xylose were the least degraded non-starch polysaccharide residues in all fractions.     

Comparison of the contribution to soil organic matter fractions,particularly carbohydrates,made by plant residues and microbial products

Soil was incubated with ¹⁴C-ryegrass or ¹⁴C-glucose, fractionated and the distribution of radioactivity in six fractions and in their constituent sugars was compared. The fractions were (1) the light fraction (d < 2.00), (2) heavy fraction which was subdivided into (3) HCl soluble, (4) humic acid, (5) fulvic acid, and (6) humin. Sugars were released from soluble fractions by hydrolysis with 0.5M H₂SO₄, and from insoluble fractions by hydrolysis with 2.5M H₂SO₄ and 12M H₂SO₄ followed by 0.5M H₂SO₄. The light fraction contained the greater part of the radioactivity and the sugars in both types of incubation. The proportion of the radioactivity accounted for by sugars in the light fraction of the ryegrass incubation, initially 44%, decreased to 30% after 6 months incubation and to 19% after a year. In one of the glucose incubations, done with soil that had been dried prior to remoistening to 25% w/w and incubating, the proportion was 17% after incubation for one month; in the other, done on soil that had not been given a drying treatment and had a 35% w/w moisture content, it was 32%. In the ryegrass incubation, the sugars with the greatest specific activities were present in the light fraction. In contrast, in the glucose incubation, sugars in the HCl-soluble, fulvic and humic fractions had the highest specific activities. Carbon from ryegrass contributed more to the humic acid and humin fractions of the soil than did the carbon from glucose, whereas carbon from glucose made a greater contribution to the acid-soluble organic matter.     

Proximate composition,mineral and amino acid content of mature Canavalia gladiata seeds

The chemical composition and the nutritional quality of protein and carbohydrates of mature seeds of Canavalia gladiata (L.) were investigated. The whole and cotyledon flour of mature seeds contained; crude protein 26.8 and 29.2%; fat 2.8 and 3.1%; fibre 33.2 and 10.2%; ash 3.9 and 4.3%; carbohydrate 33.3 and 53.2% on dry matter basis respectively. The carbohydrate fractions have starch contents of 30.7 and 39.6% and 27.7 and 34.6 mg g⁻¹ low molecular weight carbohydrates on dry matter basis. The energy content of whole seed and cotyledon flour was 11,082 and 14,923 kJ kg⁻¹. Sucrose represents the highest fraction of low molecular weight carbohydrates with fructose being the lowest. The mineral analysis showed K, Mg, Ca, P and S to be present in high quantities. The essential amino acid profile compared well with FAO/WHO recommended pattern except for sulphur containing amino acids, cysteine and methionine. Therefore the chemical composition of the raw mature seeds of Canavalia gladiata (kernel) indicates the bean to be a good supplement to cereal-based diets.     

Effects of carboxymethylation,hydroxypropylation and dual-enzyme hydrolysis combination with heating on in vitro hypoglycaemic properties of coconut cake dietary fibres

Effects of carboxymethylation, hydroxypropylation and dual-enzyme hydrolysis combined with heating on in vitro hypoglycaemic properties of coconut cake dietary fibre (CCDF) were studied. Results showed that all the three modification methods could effectively improve (P < 0.05) the glucose-adsorption ability (GAA), glucose dialysis retardation index (GDRI), α-glucosidase and α-amylase inhibition activity of CCDF. The highest GAA (4.45–4.93 mm  g⁻¹), GDRI (85.09–86.94% mm  g⁻¹) and α-glucosidase inhibition activity (16.39–19.37%) were found on CCDFs modified by hydroxypropylation and carboxymethylation, attributed to the increased soluble dietary fibre content, viscosity and water retention and swelling capacity. Moreover, CCDF treated by enzymatic hydrolysis combined with heating demonstrated the highest α-amylase inhibition activity (53.95%), attributed to the high specific surface area, more porous surface structure and formation of fibre–amylase complex proved by fluorescence spectroscopy. These results suggest that the modified CCDFs could be used as low-calorie functional ingredients in food or other industries.     

Nutritional value and functional properties of a hydrocolloidal soybean and oat blend for use in Asian foods

A rheological study was conducted to determine the functional properties of a hydrocolloidal blend of soybean flour and oat bran, called Soytrim. Soytrim was prepared by thermomechanically processing soybean and oat products. After finding that Soytrim had similar rheological characteristics to coconut and soybean milk products, two studies were conducted to investigate its use in improving the nutritional value of some Asian foods by reducing the saturated fat content and increasing the soluble fibre content. In the first study, four Thai foods were prepared using a 60 g kg^?1 Soytrim suspension to replace some of the coconut milk, with subsequent sensory, chemical and physical analysis. A 750 g kg^?1 substitution of Soytrim for coconut milk in green chicken curry gave a 74.7% reduction in saturated fat content and a 142.8% increase in soluble fibre content. Total substition of Soytrim for coconut milk in fermented soybean dip gave a 96.2% reduction in saturated fat and a 10.6% increase in soluble fibre. Total substitution in mungbean conserve gave a 97.0% reduction in saturated fat and a 19.0% increase in soluble fibre. A 500 g kg^?1 substitution of soytrim for coconut milk in sweetened condensed cassava paste gave a 48.7% reduction in saturated fat and 37.5% increase in soluble fibre. Sensory evaluation of these foods revealed no distinguishable changes in acceptability at the 500 g kg^?1 replacement level, but unacceptability with total substitution. In the second study, more widely consumed Asian foods, soymilk and tofu, were combined with Soytrim. These foods could also be made more nutritious when combined with Soytrim at rates of substitution up to 300 g kg^?1, with satisfactory acceptability at this replacement level. In all the Asian foods studied, the hydrocolloidal blend of soybean flour and oat bran could add nutritional value by reducing saturated fat and increasing soluble fibre. © 2002 Society of Chemical Industry     

Neutral-sugar determination by HPAEC-PAD to characterise polysaccharide degradation by colonic bacteria

 In vitro methods are widely used to characterise dietary fibre fermentability in the human hind gut. The activity of faecal bacteria can be followed by measuring fermentation products and substrate degradation. This paper describes a method for establishing neutral-sugar profiles by HPAEC-PAD during in vitro fermentation studies. Freeze-dried fermentation residues are hydrolysed with H₂SO₄, and the monomers are separated on an anion-exchange column using a reverse NaOH gradient. Sulphate ions are removed from hydrolysates on-line with a special ion-exchange guard column. 2-D-deoxyribose is used as internal standard for quantification. A method for separating all neutral sugars that typically occur in dietary fibre is given. Possibilities for enhancing the resolution for other purposes are suggested. Compared to GC the described method is particularly attractive for routine analyses. Data relating to the decreasing levels of neutral sugars in fermentation residues of oat bran fractions that differ in their mixed-linked β-glucan content are given and degradation patterns of the polysaccharides present in these substrates are discussed. Received: 26 February 1997     

Composition of cell walls isolated from cell types of grain sorghum stems

Cell types were isolated from sorghum stems at two stages of development, anthesis and grain maturity, to study cell wall characteristics. Cell walls were isolated from epidermis (EPID), sclerenchyma (SCL), vascular bundle zone (VBZ), inner vascular bundles (IVB) and pith parenchyma cells (PITH) and analysed for total carbohydrate, acid insoluble lignin, total uronosyls, neutral sugars and hydroxycinnamic acids. In addition, walls from SCL, VBZ, IVB and PITH were subjected to chemical fractionation to separate wall carbohydrate into polysaccharide groups. Although wall characteristics were similar at both plant maturities, there were differences in lignin concentration, hydroxycinnamic acids, and carbohydrate composition among the cell wall types. Lignin was lowest in the PITH walls (169 g kg⁻¹) and highest in SCL and EPID (c 211 g kg⁻¹). Cellulose was most abundant in VBZ and SCL walls with greater secondary wall formation. Pectic materials were most abundant in PITH walls. Xylans were similar among wall types except for EPID that contained higher amounts of xylose. Releasable hydroxycinnamates were not as consistent among the cell wall types. Total ferulates, including ester linked and releasable ether linked, tended to increase from PITH to SCL (8 to 15 g kg⁻¹ CW) with an increase in the proportion etherified within the wall matrices (PITH 51%; SCL 66%). Total p‐coumarates showed opposite trends with PITH walls having significantly more (35 g kg⁻¹ CW) than VBZ or SCL (19 and 13 g kg⁻¹ CW). EPID walls contained the least pCA (6.5 g kg⁻¹ CW). Except for the hydroxycinnamates, compositional trends for the different wall types would reflect changes from primary walls to increased amounts of secondary wall. Neutral sugar analysis of indigestible residues indicated similar carbohydrate compositions among the cell wall types, with xylose being less degradable than all other wall sugars. © 1999 Society of Chemical Industry     

The composition of maturing Omani dates

The composition of two varieties of Omani dates, fard and khalas, was determined as maturity progressed. Free sugars and dietary fibre content were examined in detail. High-performance liquid chromatography (HPLC) of the extracts showed that at the early green stage (Arabic kimri), dates contained small amounts of glucose and fructose. At the intermediate yellow (khalal) and red (rutab) stages, large amounts (500–565 g kg⁻¹ dry weight) of sucrose had accumulated, but no additional glucose or fructose was detected. At the final mature (tamar) stage, all sucrose was converted to glucose and fructose (>800 g kg⁻¹ dry weight). Dietary fibre, determined as non-starch polysaccharides (NSPs) by gas chromatography (GC), decreased from 250 g kg⁻¹ (kimri) to 50 g kg⁻¹ (tamar) on a dry weight basis. The principal monomers of NSPs were glucose, galactose, xylose, mannose, arabinose and rhamnose. On a dry weight basis, pectin, protein and ash contents decreased as the dates matured. On a fresh weight basis, changes in NSPs, pectin, protein and ash could be attributed to loss of moisture and the accumulation of sucrose initially, or of invert sugar later as maturation progressed. © 1999 Society of Chemical Industry     

Laminarin in the dietary fibre concept

Dietary fibres consist of edible plant polysaccharides that are resistant to digestion and absorption in the human small intestine but undergo complete or partial fermentation in the colon. Seaweeds, notably Laminaria spp, are particularly rich in polysaccharides resistant to hydrolysis in the upper gastrointestinal tract and are, in consequence, considered as dietary fibres. Most of the carbohydrates from Laminaria spp are thought to be indigestible by humans. The main storage polysaccharide of these algae is laminarin, a β‐polymer of glucose. The aims of this work were, on the one hand, to compare various methods of extraction of laminarin by partial characterisation of the product obtained and, on the other hand, to study the fate of this polysaccharide and its effects in the gastrointestinal tract in order to determine its potential as a dietary fibre in human nutrition. Among four methods tested to extract laminarin, the best appeared to be a hot HCl‐based method. Human digestive enzymes did not hydrolyse laminarin, so this polysaccharide can be considered as a dietary fibre. After ingestion by rats, this polysaccharide was not found in faeces of these animals. It did not increase the intestinal transit and stool output in vivo, but it increased the contractile response of the stomach to acetylcholine in vitro. Copyright © 2004 Society of Chemical Industry     

Dietary fibre level and enzyme inclusion affect nutrient digestibility and excreta characteristics in grower pigs

An experiment was conducted with 12 grower pigs to determine the effects of (1) manipulating dietary neutral detergent fibre (NDF) level and (2) dietary inclusion of fibre‐degrading enzymes on nutrient digestibility and excreta characteristics in pigs. Four diets were formulated to contain three levels of NDF: 1, 66 g kg^?1 NDF (low fibre); 2, 121 g kg^?1 NDF (moderate fibre); 3, 222 g kg^?1 NDF (high fibre); 4, diet 3 plus 2.0 g kg^?1 enzyme. Increasing levels of dietary NDF linearly decreased dry matter and energy digestibilities (r² = 0.99, P < 0.05). Lowering dietary NDF from 222 to 121 g kg^?1 improved nitrogen digestibility by 13% (P < 0.01). Faecal production was decreased by 9% for each 1% decrease in dietary NDF content (r² = 0.99, P < 0.05). Inclusion of fibre‐degrading enzymes in the high‐fibre diet improved dry matter and energy digestibilities by 2 and 3% respectively, and reduced faecal production by 10% (P < 0.01). Faecal and manure (faeces plus urine) pH values from pigs fed the high‐fibre diet and the high‐fibre plus enzyme diet were lower than those from pigs fed the other experimental diets (P < 0.05). In conclusion, lowering the dietary NDF level or inclusion of fibre‐degrading enzymes in high‐fibre diets may offer relatively practical and easy methods for reducing waste production in pigs. © 2002 Society of Chemical Industry     

Lignification of switchgrass (Panicum virgatum) and big bluestem (Andropogon gerardii) plant parts during maturation and its effect on fibre degradability

Five cultivars of switchgrass (Panicum virgatum L) and four cultivars of big bluestem (Andropogon gerardii Vitman) were harvested at vegetative, boot and heading stages of maturity. Leaf and stem fractions were analysed for detergent fibre composition and 48-h ruminal in-vitro degradability, ester- and ether-linked non-core lignin phenolic acids, and core lignin composition. Big bluestem leaves contained more neutral detergent fibre than switchgrass, but general composition of the fibre did not differ. Stem fibre of switchgrass had relatively lower levels of cellulose and lignin at the vegetative stage than observed in big bluestem. Esterified and etherified p-coumaric and ferulic acid concentrations were generally higher in switchgrass plant parts. Yield of nitrobenzene oxidation products from core lignin was greater for switchgrass leaves, but very little difference in composition was noted. Leaf tissue contained lower concentrations of all lignin components than stems. Maturation resulted in increased total lignification, but all components did not respond in the same manner. Variation for all measures of lignification seemed to be as great within species as between the grass species. Degradability of fibre declined with maturation. The only species difference was that switchgrass fibre was more degradable at the vegetative stage. Relationships between lignification and fibre degradability were in agreement with some, but not all, previously reported relationships. Concentration of core lignin was only a significant predictor of fibre degradability when the relationship was examined across maturity stages. Within a stage of maturity, lignin composition was more closely related to fibre degradability than was concentration. However, the best predictors of fibre digestibility differed among species, plant part and maturity.     

Preparation and characterisation of dietary fibre from sugar beet pulp

Dried sugar beet pulp was ground and washed with 95% ethanol in order to obtain a colourless and odourless product which could be used as dietary fibre after drying and sieving. Sugar beet fibre had the same chemical composition as the initial pulp: 26–32% of hemicelluloses, 22–24% cellulose, 21.5–23% uronic acids, ～1–2% lignin, ～7–8% protein, 7.5–12% ash and ～0.5% residual sucrose. The main physicochemical properties such as density, cation exchange capacity (～0.6 meq g^?1) and water holding capacity (24–32 g g^?1) were determined. The water holding capacity of sugar beet fibre was only slightly affected by pH and ionic strength (adjusted by NaCl or CaCl₂) but it held less water in the H⁺ form than in the salt form, Na⁺ or Ca²⁺.     

Nutrient composition of taro (Colocasia esculenta) cultivars from the Papua New Guinea Highlands

Taro samples were analysed for water, protein, fat, fructose, glucose, sucrose, maltose, starch, organic acids, dietary fibre, ash, sodium, potassium, iron, calcium, magnesium and zinc and the energy content was calculated. The composition of ‘Yaguat’ taro was determined at various intervals during growth. The most marked changes were in immature corms with a decrease in water content and an increase in starch and energy content. There were minimal changes in composition of taro from slightly immature to over-mature stages. The composition of 36 samples of mature taro from 22 cultivars grown in four districts was determined. There was a large range in proximate composition between cultivars for most nutrients; for example, water ranged from 55.8 to 74.4 g 100 g^?1, starch 20.0 to 35.1 g 100 g^?1 protein 0.5 to 2.1 g 100 g^?1, dietary fibre 1.4 to 5.4 g 100 g^?1 and energy 403 to 672 kJ 100 g^?1. However the same cultivar grown in two districts tended to have a similar composition. Mineral levels were variable between samples but the greatest variation was with zinc which varied widely between districts.