Effect of addition of cryoprotectants on the mechanical properties, colour and sensory attributes of fresh and frozen/thawed mashed potatoes

Cryoprotectants such as hydrocolloids (amidated low-methoxyl (ALM) and high methoxyl (HM) pectins), kappa- and iota-carrageenans (k-C and i-C), xanthan gum (XG)) and dairy proteins [whey protein (WP), sodium caseinate (SC)] were added to mashed potatoes to investigate ways of improving the effects of freezing and thawing. It was found that each hydrocolloid and protein, depending on concentration, affected the mechanical properties [instrumental textural profile analysis (ITPA), cone penetration (CP) test], the total colour difference (ΔE*) with respect to fresh control (FC) and the sensory attributes of fresh (F) and frozen/thawed (F/T) mashed potatoes in a different way. In the F/T samples, adding 5 and 8 g kg⁻¹ ALM, 3, 5 and 8 g kg⁻¹ k-C, 1.5, 3, 5 and 8 g kg⁻¹ i-C and 1.5, 5 and 15 g kg⁻¹ WP significantly increased ITPA consistency. Also, adding 2.5 and 5 g kg⁻¹ XG significantly increased ITPA consistency of the F/T product. In both F and F/T samples, k-C provided the highest ITPA consistency and also high CP average force evidencing a stronger synergistic effect in κ-C/denatured milk protein systems, although the excessive thickening and stickiness provided was judged undesirable by the panellists. Adding 8 g kg⁻¹ HM pectin had a disruptive effect on the mashed potatoes and decreased both ITPA consistency and CP average force. In all cases, freezing and thawing reinforced the gel structure of the products as compared to F and FC counterparts. The ΔE* values were higher in F samples containing ALM and HM pectins. Dairy proteins affected the taste and odour of the mashed potatoes and were judged unacceptable in the sensory analysis. Samples containing 0.5 and 1.5 g kg⁻¹ added XG were preferred organoleptically due to the creamy mouthfeel it produced. ITPA consistency correlated well with sensory texture attributes.     

Oscillatory Rheological Properties of Fresh and Frozen/Thawed Mashed Potatoes as Modified by Different Cryoprotectants

Five different hydrocolloids (amidated low-methoxyl [ALM] and high-methoxyl [HM] pectins, kappa- and iota-carrageenans [κ-C and ι-C], and xanthan gum [XG]) and two dairy proteins (whey protein [WP] and sodium caseinate [SC]) were added at five different concentrations to fresh (F) and frozen/thawed (F/T) mashed potatoes to investigate ways of improving the effects of freezing and thawing. It was found that each hydrocolloid and protein, depending on the concentration, affected the viscoelastic properties of F and F/T mashed potatoes in a different way. Color, drip loss (DL), total soluble solid (TSS) content, and overall acceptability (OA) were also determined. All systems showed weak gel behavior, although the F samples exhibited higher values of G′ and G″ as compared to F/T counterparts. However, the effects were highly dependent on the type and level of biopolymer added. F and F/T mashed potatoes with added WP presented higher values of G′ and G″, and values were lowest in both when XG was added. After freezing and thawing, the addition of ingredients (3 to 5 g kg⁻¹ ALM and HM, 3 to 8 g kg⁻¹ κ-C, and 1.5 g kg⁻¹ WP) had the effect of thickening the mash and thus improving freeze/thaw stability. Processed samples were darker than F samples, although this darkening was not detected by the panelists. Color was affected less by κ-C or ι-C than by the other ingredients added. ALM pectin, κ-C and ι-C, XG, and SC all exhibited water-holding capability, whereas HM and WP did not. The product yielded by XG was softer than controls without added cryoprotectants in both F and F/T samples, but samples containing 0.5 and 1.5 g kg⁻¹ added XG were judged more acceptable than the F control because of the creamy mouth-feel it produced.     

Effect of dietary fibre and MTGase on the quality of mackerel surimi gels

BACKGROUND: The effects of microbial transglutaminase (MTGase; 5 g kg^?1) and dietary fibre (inner pea fibre and chicory root inulin, 20 and 40 g kg^?1) on gels from surimi made with Atlantic (Scomber scombrus) and chub mackerel (Scomber japonicus) were studied with the purpose of achieving a better understanding of the underlying phenomena and improving gels. RESULTS: MTGase addition improved textural properties (namely, cohesiveness increased from 0.19–0.41 to 0.59–0.72) and increased pH and water‐holding capacity (WHC). Moreover, MTGase reduced the elastic and viscous modules and darkened gels; protein solubility declined, meaning greater protein aggregation, according to electropherograms. MTGase had no unequivocal effect upon the gels' microstructure. Pea fibre increased hardness (an increase of almost 60% with 40 g kg^?1) and related parameters, the elastic and viscous modules and WHC. Pea fibre reduced extractable protein in sodium dodecyl sulfate and urea (in the absence of MTGase) as well. Scanning electron microscopy revealed different structures for gels containing pea fibre. Regarding inulin, it worsened textural quality and WHC. CONCLUSION: A combination of MTGase and pea fibre can improve a poor quality surimi. Copyright © 2009 Society of Chemical Industry     

Development of low‐fat mayonnaise containing polysaccharide gums as functional ingredients

BACKGROUND: The objective of this study was to develop a low‐fat (LF) mayonnaise containing polysaccharide gums as functional ingredients. Xanthan gum (XG, 15 g kg^?1), citrus fiber (CF, 100 g kg^?1) and variable concentration of guar gum (GG) were used to formulate the optimum ratios of polysaccharide gums as fat replacers. The fat content in LF mayonnaise was reduced to 50% if compared with full‐fat (FF) mayonnaise, and the products still maintained ideal rheological properties. RESULTS: The rheological parameters showed that there were no (P > 0.05) differences in yield stress, viscosity and flow behavior index between XG + 10 g kg^?1 GG, CF + 5 g kg^?1 GG and FF control. LF mayonnaises had lower caloric values and higher dietary fiber content than the FF counterpart. Scanning electron microscopy (SEM) micrographs illustrated that the network of aggregated droplets in LF treatments contained a large number of interspaced voids of varying dimensions. Furthermore, in a comparison of sensory evaluation of LF treatments with commercial and our FF mayonnaises, there were no (P > 0.05) differences in any sensory scores among XG + 10 g kg^?1 GG control. CONCLUSION: This study shows that XG + 10 g kg^?1 GG and CF + 5 g kg^?1 GG could be used in LF mayonnaise formulations based on its multiple functions on processing properties. Copyright © 2010 Society of Chemical Industry     

Comparative study of the mineral composition of several varieties of potatoes (Solanum tuberosum L.) from different countries cultivated in Canary Islands (Spain)

Potatoes are a basic component of human diets worldwide being an excellent source of minerals linked the maintenance of health. Contents of calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), cupper (Cu), iron (Fe), manganese (Mn), zinc (Zn), nickel (Ni) and chromium (Cr) in seventy‐four fresh potato samples from different varieties consumed in Tenerife Island (Canary Islands, Spain) were determined by flame atomic absorption spetrometry (FAAS). The mean concentrations were 60.1 mg kg^?1, 222 mg kg^?1, 5047 mg kg^?1, 125 mg kg^?1, 1.69 mg kg^?1, 8 mg kg^?1, 1.70 mg kg^?1, 3.88 mg kg^?1, 62.7 μg kg^?1 and 19.9 μg kg^?1 for Ca, Mg, K, Na, Cu, Fe, Mn, Zn, Ni and Cr, respectively. The varieties of local potatoes presented higher mineral contents than imported potatoes. Potassium presented the highest contents in all varieties of potatoes. Iron was the most abundant microelement. Local potatoes offer greater nutritional contributions to the recommended intakes than imported varieties. Within the macrominerals, the highest contribution to the intakes was observed for K, while Fe was the trace element with the largest contribution to the proposed intake.     

Quality of mashed potatoes: effect of adding blends of kappa-carrageenan and xanthan gum

Blends of kappa-carrageenan (K) and xanthan gum (X) were added to mashed potatoes. Product was tested by instrumental texture profile analysis and cone penetration tests, oscillatory and steady rheology, colour, drip loss, total soluble solids and sensory analyses. A central composite rotatable design was used to study the effects of variation in levels of K (1.5–4.5 g kg⁻¹) and X (0.5–2.5 g kg⁻¹) concentrations. Addition of K had a major impact on gel strength, viscoelastic behaviour, sensory attributes and overall acceptability, whereas addition of X influenced textural and steady properties and colour. Mainly, elastic modulus (G′) was strongly dependent on the K concentration in mashed potatoes containing amylose. As compared to mashed potatoes with 1.5 g kg⁻¹ added X, additional incorporation of 5.12 g kg⁻¹ K increased G′ approximately twofold, possibly due to exclusion effect of the swollen starch granules and synergistic effect of K and denatured protein. The function of X in the mashed potatoes may in fact be confined to that of a filler rather than a dynamic constituent, although it does affect yield stress behaviour. When K/X blends (each biopolymer at 1.5 g kg⁻¹) were included in the formulation, the product exhibited very acceptable sensory quality. K provided the appropriate texture, while X imparted creaminess and mouthfeel to the product.     

Maternal dietary conjugated linoleic acid is not directly toxic for the developing chick embryo,but causes embryo mortality by altering fatty acid composition of the egg yolk in the chicken

BACKGROUND: Conjugated linoleic acid (CLA) was shown to cause embryo mortality when added into chicken diets. The objective of this study was to determine if CLA accumulation in yolk was directly responsible for embryo mortality. MATERIAL AND METHODS: Forty‐two 30‐week‐old hens were assigned to seven groups and fed a diet containing 5 g kg^?1 canola oil (Group A), 5 g kg^?1 CLA (Group B), 5 g kg^?1 CLA plus 20 g kg^?1 canola oil (Group C), 5 g kg^?1CLA plus 30 g kg^?1 canola oil (Group D), 5 g kg^?1 CLA plus 40 g kg^?1 canola oil (Group E), 10 g kg^?1 CLA plus 40 g kg^?1 canola oil (Group F) or 20 g kg^?1 CLA plus 40 g kg^?1 canola oil (Group G) for 22 days. Collected eggs were held at 15 °C for 24 h, and then incubated. For fatty acid analysis, three eggs were collected on the 22^nd day of the study. RESULTS: After the sixth day, embryonic mortality was 100% in eggs from Group B versus 2, 30, 21, 4, 0, and 9% in groups A, C, D, E, F and G, respectively. The ratio of SFA/UFA of yolks from groups A, B, C, D, E, F and G was 0.64, 1.53, 1.07, 1.06, 1.08, 1.05 and 1.13, respectively. Relative levels (%) of CLA in the eggs from the groups A, B, C, D, E, F and G were 0.12, 2.29, 1.68, 1.80, 1.76, 3.04, and 5.25%, respectively. CONCLUSION: This study showed that CLA was not directly toxic for developing embryo, but caused mortality in the fertile eggs by increasing the ratio of SFA to UFA in egg yolk. Copyright © 2009 Society of Chemical Industry     

The effect of modified starches on the gel properties and protein conformation of Nemipterus virgatus surimi

The study investigated the effect of native cassava starch (NCS), hydroxypropylated starch, acetic acid esterification starch (AAES), acetylated distarch phosphate on gel properties and protein conformation of Nemipterus virgatus surimi. Addition of 10 g kg^?1 NCS or 20 g kg^?1 AAES could significantly promote the gel strength and textural profiles of the surimi gels (p < .05). The water holding ability and whiteness of surimi were remarkably increased when the four types of starch were added at all concentrations (p < .05). In rheological test, the lower G′ was observed in surimi samples added with starch at low temperature, suggesting starch played an inactive filler role in surimi. Along with the increase of starch additive amount, ionic bond and hydrophobic interaction first increased and then decreased, while hydrogen bond first decrease and then increased. According to Raman spectroscopy data, small content of starch promoted the heat‐induced conformational transition of surimi protein from α‐helix to β‐sheet, leading to the change in gel properties of surimi gels. Scanning electron microscopy photographs showed surimi gels added with 20 g kg^?1 starch had the finer and denser network structure. Therefore, 20 g kg^?1 AAES or 10 g kg^?1 NCS or 10 g kg^?1 HS could be proposed to a potential modifier to effectively improve the quality of surimi products.     

Quality of dried white salted noodles affected by microbial transglutaminase

To examine the potential application of microbial transglutaminase (MTGase) in oriental noodle making, the effects of various MTGase addition levels on the rheological, textural and structural properties of noodles were investigated using good quality (‘Red Bicycle’) and poor quality (‘Sandow’) wheat flours. Addition of MTGase at 5–20 g kg^?1 levels, but not at 1 g kg^?1 level, to the two different wheat flours decreased rapid visco‐analyser (RVA) parameters of hot paste viscosity and final viscosity while increasing breakdown. For fresh white salted noodle dough sheets, the storage modulus (G′) and loss modulus (G″) increased significantly at 1 g kg^?1 MTGase addition for both types of flour, but there was no clear trend with higher levels of MTGase. For dried white salted noodles, textural parameters (tensile force, hardness and gumminess) generally increased, cooking loss was little affected and the yield of the cooked noodle was significantly decreased by MTGase. Color was slightly adversely affected. Scanning electron microscopy (SEM) results indicated that physical properties of dry noodles were improved through the formation of cross‐links [ε‐(γ‐glutamyl)lysine] by MTGase. Copyright © 2005 Society of Chemical Industry     

Effect of aflatoxin,ochratoxin and their combination on protein and energy utilisation in white leghorn laying hens

The effect of dietary aflatoxin B₁ (AF) at levels of 0.5, 1 and 2 mg kg^?1, ochratoxin A (OA) at levels of 1, 2 and 4 mg kg^?1 and their corresponding combinations on protein and energy utilisation as well as energy partitioning was studied in white leghorn laying hens. Protein retention was adversely affected at all levels of AF and OA either singly or in combination, though the effect was more evident with OA and AF + OA. Minimum protein retention was recorded in hens fed the combination of toxins at their highest levels (2 mg kg^?1 AF + 4 mg kg^?1 OA). Aflatoxin at 1 and 2 mg kg^?1 and OA and AF + OA at all levels caused a significant reduction in metabolisable energy (ME) value of the diets. The minimum ME value was recorded for the diet containing both toxins at their highest levels (2 mg kg^?1 AF + 4 mg kg^?1 OA). A significant depression in egg energy deposition was observed with dietary inclusion of 1 and 2 mg kg^?1 AF, 2 and 4 mg kg^?1 OA and all levels of AF + OA in period I. In period II the reduction in egg energy deposition was significant at all levels of toxins either singly or in combination. Body energy deposition was adversely affected in hens fed the highest levels of AF (2 mg kg^?1) and OA (4 mg kg^?1) and all levels of AF + OA in period I. However, in period II a significant decrease in body energy deposition was observed at all levels of toxins except 1 mg kg^?1 OA. A significant increase in maintenance energy (ME_m/W^0.75 day^?1) requirement was recorded in hens fed 2 mg kg^?1 AF, 4 mg kg^?1 OA and all levels of AF + OA. It is suggested that AF and OA either singly or in combination affect not only protein and energy utilisation in laying hens but also energy partitioning i.e. egg and body energy deposition and maintenance energy requirement. However, the combination of toxins (AF + OA) has more severe adverse effects on all parameters than the individual toxins because of their synergistic toxicity effect. Copyright © 2007 Society of Chemical Industry     

Effect of various levels of aflatoxin and ochratoxin A and combinations thereof on protein and energy utilisation in broilers

Studies were conducted to evaluate protein and energy utilisation in broilers fed diets containing various levels of aflatoxin (AF; 0, 0.5, 1 and 2 mg kg^?1) and ochratoxin A (OA; 0, 1, 2 and 4 mg kg^?1) either singly or in different combinations. Total protein efficiency (TPE) was reduced by 50.97, 76.52 and 132.75% at 2 mg kg^?1 AF and 2 and 4 mg kg^?1 OA respectively. Co‐toxicity at two levels, 1 mg kg^?1 AF + 2 mg kg^?1 OA and 2 mg kg^?1 AF + 4 mg kg^?1 OA, resulted in significant reductions of 78.58 and 127.43% respectively in TPE. AF at all three levels and OA at 2 and 4 mg kg^?1 caused significant decreases in net protein utilisation (NPU). Co‐toxicity at all three levels led to significantly lower NPU. The reduction in NPU ranged from 18.68% at 0.5 mg kg^?1 AF to 75.12% at 2 mg kg^?1 AF + 4 mg kg^?1 OA. Significant reductions in metabolisable energy (ME) content were recorded at 1 and 2 mg kg^?1 AF and all three levels of OA. ME content was reduced drastically when both toxins were fed simultaneously. It is suggested that both AF and OA adversely affect energy and protein utilisation in broilers, and this effect is exacerbated when both toxins are fed simultaneously. © 2002 Society of Chemical Industry     

Effect of microbial transglutaminase on autolysis and gelation of lizardfish surimi

In the absence of microbial transglutaminase (MTGase), the textural properties of lizardfish surimi (Saurida spp) improved when pre‐incubated at 4 and 25 °C for 24 and 4 h, respectively. MTGase optimally catalyzed incorporation of monodansylcadaverine (MDC) into surimi at 40 °C. Addition of MTGase appeared to reduce autolytic activity at 25 and 40 °C, but had no effect on autolytic activity at 65 °C. Breaking force and deformation of lizardfish surimi significantly improved when 0.1 unit MTGase g^?1 surimi (1.8 g kg^?1) was added and pre‐incubated at either 25 or 40 °C. Textural properties improved concomitant with cross‐linked polymers of myosin heavy chain and tropomyosin, but not actin. Addition of MTGase also improved the storage modulus (G′). The gel network of surimi mixed with MTGase and pre‐incubated at 40 °C readily formed during the pre‐incubation period, while formation of the gel network began at 48.1 °C in the absence of MTGase. Copyright © 2005 Society of Chemical Industry     

Dietary acrylamide exposure among Finnish adults and children: the potential effect of reduction measures

A deterministic exposure assessment using the Nusser method that adjusts for within-subject variation and for nuisance effects among Finnish children and adults was carried out. The food consumption data covered 2038 adults (25–74 years old) and 1514 children of 1, 3 and 6 years of age, with the data on foods’ acrylamide content obtained from published Finnish studies. We found that acrylamide exposure was highest among the 3-year-old children (median?=?1.01?µg?kg^?1?bw^?day^?1, 97.5th percentile?=?1.95?µg?kg^?1?bw^?day^?1) and lowest among 65–74-year-old women (median?=?0.31?µg?kg^?1?bw^?day^?1, 97.5th percentile?=?0.69?µg?kg^?1?bw^?day^?1). Among adults, the most important source of acrylamide exposure was coffee, followed by casseroles rich in starch, then rye bread. Among children, the most important sources were casseroles rich in starch and then biscuits and, finally, chips and other fried potatoes. Replacing lightly roasted coffee with dark-roasted, swapping sweet wheat buns for biscuits, and decreasing the acrylamide content of starch-based casseroles and rye bread by 50% would result in a 50% decrease in acrylamide exposure in adults. Among children, substituting boiled potatoes for chips and other friend potatoes and replacing biscuits with sweet wheat buns while lowering the acrylamide content of starch-based casseroles by 50% would lead to acrylamide exposure that is only half of the original exposure. In conclusions, dietary modifications could have a large impact in decreasing acrylamide exposure.     

Fat reduction in emulsion sausage using an enzyme‐modified potato starch

BACKGROUND: A heat‐stable amylase‐modified potato starch (MPS) was prepared and used as a fat replacer in reduced‐fat emulsion sausages. The effects of fat level (50, 150 and 300 g kg^?1) and MPS addition (20 and 40 g kg^?1) on energy, colour, sensory, and textural properties of emulsion sausages were investigated. RESULTS: The addition of 20 or 40 g kg^?1 of MPS in reduced‐fat sausage (50–150 g kg^?1 fat) reduced total energy (15.1–49.4%), increased lightness, but lowered redness of the products (P < 0.05). The 150 g kg^?1 or 50 g kg^?1 fat sausages containing 20 g kg^?1 MPS had a similar hardness to the 300 g kg^?1 fat control (P > 0.05). Sensory evaluation indicated that the presence of MPS in reduced‐fat sausages increased (P < 0.05) the product's tenderness. CONCLUSION: Overall, the 150 g kg^?1 fat emulsion sausages with 20 g kg^?1 MPS were comparable to the 300 g kg^?1 fat control sausage in colour, texture profile, and sensory properties, but was lower in energy, suggesting that the MPS can be used as a potential fat replacer in sausage products. Copyright © 2008 Society of Chemical Industry     

Development of low-fat and low-calorie beef sausage using modified starch as fat replacement agent

BACKGROUND: The effects of modified waxy maize starch (MWMS, 10–32.5 g kg^?1) as a replacement for varying levels of oil or both oil and wheat flour (WF) on the chemical and technological characteristics of 60% beef sausages were investigated. RESULTS: Addition of MWMS increased water‐holding capacity and decreased moisture content and both cooking and purge losses. Incorporation of MWMS improved organoleptic acceptance compared with control sausages. CONCLUSION: Sausage formula 5 (F5), containing 20 g kg^?1 MWMS and 50 g kg^?1 WF, was better (P < 0.05) than all other formulae. The total caloric content of the sausages decreased significantly with decreasing fat level (P < 0.05); for example, the decrease in fat content of 57.4% in F5 led to a significant decrease in energy value of 34.9% (P < 0.05). Copyright © 2011 Society of Chemical Industry     

Quality characteristics of a non‐fermented dry‐cured sausage formulated with lemon albedo

Dry‐cured sausages were treated with two types of dehydrated lemon albedo (raw and cooked) at five concentrations (0–100 g kg^?1 in 25 g kg^?1 increments). Several physical and chemical analyses were made during the drying stage, and compositional, textural and sensory analyses were conducted on the finished products. The addition of albedo improved the nutritional properties as a result of fibre addition and may have beneficial effects due to the presence of active biocompounds as evidenced by a decrease in residual nitrite levels and delayed oxidation (based on TBARS values). The sensory properties of samples that resembled the control sausages were those that contained up to 50 g kg^?1 dehydrated raw albedo and 75 g kg^?1 dehydrated cooked albedo. Copyright © 2004 Society of Chemical Industry     

A rheological characterisation of mashed potatoes enriched with soy protein isolate

The effect of the addition of soy protein isolate (SPI) (0, 15, 30, 45 and 60 g kg⁻¹) on viscoelastic properties, large deformation measurements and microstructure of fresh (FM) and frozen/thawed (F/TM) mashed potatoes was investigated. Rheological data showed weak gel behaviour for both FM and F/TM potatoes without and with added SPI together with a significant decrease of system viscoelasticity (G′ and G″) with increasing SPI volume fraction, primarily attributed to the no interaction between the amylose/amylopectine matrix and the dispersed SPI particles or aggregates as revealed by scanning electron microscopy (SEM). Micrographs also showed that SPI formed white coarse aggregates. A freeze/thaw cycle produced a more significant decrease in viscoelastic functions, due to superior aggregation of denatured SPI and reduced water activity. In F/TM samples, high correlations between small and large deformation measurements were found. Results may be useful for technological applications in SPI-enriched mashed potatoes.     

Rheological,thermal and sensory properties of whey protein concentrate/pectin‐fortified mashed potatoes made from dehydrated flakes

The effect of different amounts of whey protein concentrate (50–150 g kg^?1), low and high methoxyl pectin (5–15 g kg^?1) on the rheological, thermal, structural properties and sensory quality of mashed potatoes prepared from dried mashed potatoes flakes was investigated. The response surface technique was used to analyse the effects of whey protein concentrate and pectin simultaneously on the consistency index, flow behaviour index, apparent viscosity and Casson plastic viscosity. Both whey protein concentrate and pectin decreased the consistency of the mashed potatoes weakening its structure in all concentrations assayed. Results suggest that whey protein concentrate interacts with high methoxyl pectin through non‐covalent interactions. Based on the sensory evaluation results, up to 100 g kg^?1 whey protein concentrate with 15 g kg^?1 of low methoxyl pectin and 15 g kg^?1 of high methxyl pectin could be incorporated to dried mashed potatoes flakes without losing significantly the sensory quality of the product.     

Composition,variation of nutritional contents in leaves,seed protein,fat and fatty acid profile ofchenopodium species

The foliage of Chenopodium belonging to 10 species were analysed for selected nutritional and antinutritional components. The overall range of moisture was 757-910 g kg^?1, carotenoid 78-190 mg kg^?1, vitamin C 0.5-2.4 g kg^?1, protein 26-64 g kg^?1, nitrate 2.6-5.0 g kg^?1 and oxalate 9-39 g kg^?1 (fresh wt). Variation of all the six parameters with respect to leaf position from the apex showed the highest amount of carotenoid at 7-8, vitamin C at 9-10, protein at 5-6 and nitrate in the youngest leaves, followed by a continuous decrease with age (increasing position). However, oxalate contents always tended to increase with leaf position (age). The protein, fat and fatty acid composition in seeds of eight species were also analysed. Protein varied from 106 to 142 g kg^?1 and fat from 30 to 62 g kg^?1; palmitic, oleic and linoleic were the major fatty acids in the oils.