EVALUATION OF DIETARY FIBER IN POTATO CRISPS: INFLUENCE OF THE ANALYTICAL METHOD USED

Dietary fiber in ready salted potato crisps was determined by two methods, i.e., the official AOAC method, and the modified method of Englyst, recommended in the U. K. The ultimate aim was to compare the results and to evaluate the advantages and limitations of each method for the analysis of this food in order to obtain a figure to be included on the package. The AOAC method is an enzymatic-gravimetric procedure to determine the total dietary fiber (TDF). The Englyst method consists of an enzymatic-chemical extraction and fractionation of the nonstarch polysaccharides (NSP) and their subsequent determination as neutral sugars by GLC. We modified the original chromatographic method. The AOAC method gave a value of 5.39 g/100g (dry matter) for TDF, and the Englyst method of a value of 1.70 g/100g (dry matter) for NSP. It is assumed that the gravimetric method gives a higher fiber value than the Englyst method due to a contribution from retrograded starch. For this particular food, the AOAC method is faster and much easier to carry out and does not overestimate dietary fiber, if the resistant starch is regarded as part of it.     

Chemical composition and dietary fibre of yellow and green commercial soybeans (Glycine max)

Proximate composition and dietary fibre (as non-starch polysaccharides) of yellow soybeans (from conventional, ecological, transgenic and non-transgenic crops) and green soybeans (from conventional and ecological crops) has been studied. Dietary fibre, fat and ash were significantly higher in yellow than in green samples, but moisture and available carbohydrates were significantly lower in yellow soybean than in green ones. Few statistical differences were found for protein between different samples. Soybean seeds were rich in dietary fibre (yellow: 13.7–16.5 g/100 g, green: 9.19–9.45 g/100 g). This component was evaluated as insoluble and soluble fibre, and subsequently, the neutral sugars and uronic acids were determined by gas liquid chromatography and spectrophotometry, respectively. Insoluble fibre became the predominant fibre fraction in yellow and green soybeans (74–78%), and was mainly composed of glucose, uronic acids, galactose, arabinose and xylose. Soluble fibre was between 22% and 26% in both kinds of samples and the principal monomers were uronic acids, galactose and arabinose. The major difference between total dietary fibres of yellow and green commercial samples was the proportion of galactose, which was an important constituent in yellow soybeans (21%) and a minor one in green soybeans (5%).     

Pea pod, broad bean pod and okara, potential sources of functional compounds

Disposal of by-products generated by plant food processing represent an important problem in the industry, but these by-products are also promising sources of compounds which may be used for their technological or nutritional properties, and today they are considered as a possible source of functional compounds. This work has contributed to the knowledge of three legume by-products, pea pod (Pisum sativum L.), broad bean pod (Vicia faba L.) and okara from soybean (Glycine max L.). These three by-products have in common that their major fraction is dietary fibre (pea pod: 58.6 g/100 g; okara: 54.3 g/100 g; broad bean pod: 40.1 g/100 g). Sucrose, glucose and fructose are the most important soluble sugars in both pods; however α-galactosides (stachyose and raffinose) are in greater concentration in okara. Protein is also a considerable component, although in higher amount in okara than in pods. Okara presents a large quantity of fat however both pods show similar low contents. Linoleic acid is the most important fatty acid; oleic acid is remarkable in okara and pea pod and linolenic acid in broad bean pod. Mineral amount is major in by-product pods than in okara, and the most important minerals are potassium, calcium and iron.     

Physicochemical characterisation of dietary fibre components and their ability to bind some process-induced mutagenic heterocyclic amines,Trp-P-1, Trp-P-2, AαC and MeAαC

The physicochemical properties of potato fibre, wheat bran and oat samples were investigated, along with their binding capability to heterocyclic amines (HCAs). Potato fibre displayed highest total dietary fibre content (71.8/100 g dry weight basis, dwb), followed by wheat bran (57.2/100 g dwb) and oat sample 2 (53.0/100 g dwb). Oat samples 1, 3 and 4 displayed considerably lower dietary fibre content (20.5–28.8/100 g, dwb). Oat samples 3 and 4 displayed highest soluble fibre content (70–83%), and oat sample 3 also displayed highest swelling and water retention capacity (WRC). Dietary fibre samples, except samples 3 and 4, displayed improved binding to HCAs as sample weight increased. The behaviour of wheat bran and potato fibre was similar to oat samples 1 and 2. Binding of MeAαC was comparatively greater than that of other HCAs. Dietary fibre fractions with high insoluble fibre and functional groups of HCAs may significantly contribute to the binding capacity.     

Effect of high-fat diets supplemented with okara soybean by-product on lipid profiles of plasma,liver and faeces in Syrian hamsters

The main components of okara, a by-product from soybean, are dietary fibre and protein. In this study we fed okara based diets with different amounts of fibre, protein and isoflavones to determine their effect on the lipid profile in the plasma, liver and faeces of an animal model. Male golden Syrian hamsters were fed high-fat diets supplemented with okara for 3 weeks. The supplemented diets contained 13% or 20% of okara fibre (OK-13 and OK-20), low-protein okara with 13% of fibre (OK1-13), and isoflavone-free okara with 13% of fibre (OK2-13). Okara supplemented diets did not produce significant differences in the feed intake or body weight gain (p > 0.05). The plasma levels of triglycerides, VLDL- plus LDL cholesterol and total cholesterol in hamsters fed OK-20 decreased significantly (p < 0.05) with respect to the 20% control group (C-20). However, no significant differences (p > 0.05) were found in LDL- and HDL-cholesterol plasma levels in all experiments. Total lipids, triglycerides, total and esterified cholesterol concentrations in liver were reduced by OK-20 diet. Regarding the hamsters fed OK-13 diets, the mean values of the total lipid, triglyceride and cholesterol in the plasma and liver decreased as compared to the control (C-13), but the differences were not statistically significant. All of the okara diets assayed increased the faecal excretion of total lipids, triglycerides, free cholesterol and total nitrogen (p < 0.05) compared to their respective controls. Our results suggest that the main components of okara, dietary fibre and protein, could be related with the total lipids and cholesterol decrease in the plasma and liver, as well as with the faecal output increase in high-fat fed hamsters. Okara might play an interesting role in the prevention of hyperlipidemia and could be used as a natural ingredient or supplement for functional food preparation.     

Adding value to hard date (Phoenix dactylifera L.): Compositional,functional and sensory characteristics of date jam

Second-grade dates (with a hard texture) from three potential Tunisian cultivars (Deglet Nour, Allig and Kentichi) showed the same sugar (∼73.30–89.55 g/100 g dry matter), fibre (∼7.95–18.83 g/100 g dry matter) and total phenolics (∼280.6–681.8 mg of GAE/100 g) content as dates of high quality. Deglet Nour and Kentichi varieties were characterised by a high content of sucrose and low reducing sugar content; contrary to Allig and the majority of other date varieties tested. This work intended to add value to these raw materials by using them in jam production. The corresponding jams were characterised in terms of chemical composition, physical (texture and water retention capacities) and sensory properties. Results showed a significant effect of the date variety on the composition and physical characteristics of date jams. Indeed, Allig jam was richer in reducing sugars and was characterised by its higher firmness and water retention capacity. To test the acceptability of these new products, we compared them with quince jam (the most consumed in Tunisia). Results showed that Allig and Kentichi jams presented a higher overall acceptability. However, quince and Deglet Nour jams did not show any significant differences (P > 0.05). Results from this work revealed essential information that could promote the commercialization of dzate jam.     

Compositional and functional characteristics of dates,syrups, and their by-products

Three native sun-dried date varieties from Oman (namely Mabseeli, Um-sellah, and Shahal), as well as their syrups and by-products (press cake and seed) were examined for their proximate composition, dietary fibre, total phenolics, and total antioxidant activity. Carbohydrate was the predominant component in all date varieties, syrups, and their by-products, followed by moisture, along with small amounts of protein, fat, and ash. Press cakes had the highest protein content, ranging in concentration from 3.62 g/100 g in Shahal to 5.23 g/100 g in Mabseeli, whereas fat was the highest in seeds and ranged from 5.02 g/100 g in Mabseeli to 5.90 g/100 g in Um-sellah. Seeds and press cakes were found to be good sources of dietary fibre, varied between 77.75 and 80.15 g/100 g fresh weight and between 25.39 and 33.81 g/100 g fresh weight, respectively. Among dates, syrups, and their by-products, seeds had the highest contents of total phenolics (3102–4430 mg of gallic acid equivalents/100 g fresh weight) and antioxidant activity (580–929 μmol of Trolox equivalents/g fresh weight). The results obtained suggest that date by-products (particularly seeds) serve as a good source of natural antioxidants and could potentially be considered as a functional food or functional food ingredient.     

Effects of incorporation of integral raw materials and dietary fibre on the selected nutritional and functional properties of biscuits

With the aim to develop nutritionally and functionally improved biscuits, standard wheat flour based recipe was supplemented with inulin (Raftilin) (10.5%) in combination with one of the following raw materials: soy flour, amaranth, carob (24.5%), apple fibre or oat fibre (16.5%). Various nutritional parameters such as proteins, fat, ash, carbohydrates total minerals, protein digestibility and energy value were determined in modified biscuits. Dietary fibre content, polyphenolic content and bioavailability and antioxidative activity were also assessed in the view of estimating the functionality of investigated samples. In order to evaluate the impact of technological procedure (baking) on analysed parameters, all experiments were conducted in dough samples as well. Supplementation with soy flour resulted in significant increase (p < 0.05) in protein content and digestibility (from 10.04 to 14.49 mg/100 g and from 68.9% to 81.5%, respectively). The increase of total dietary fibre content in relation to the reference sample ranged from 30.9% (sample with amaranth) to 130.6% (sample enriched with oat fibre). Best results regarding total phenolic content and antioxidative activity were achieved by incorporation of carob and apple fibre into the reference sample. Supplementation with inulin resulted in significant decrease of the total energy value of modified biscuits (from 445 to 412 kcal/100 g dry matter).     

Compositional and nutritional evaluation of several lupin seeds

Lupin seeds of different species representing diverse varieties of sweet lupin grown in Poland were investigated. The chemical compositions of lupin isolates and amino acid composition of the proteins, as well as the nutritive values were estimated. No significant differences (P ? 0.05) were observed among lupin isolates in their dry matter, crude fibre or alkaloid contents. The highest protein content (465 ± 11 g/kg d.m.) was found in seeds from lupins belonging to Lupinus luteus (P ? 0.01), while the highest oil content (ca. 115 g/kg d.m.) was found in Lupinus albus (P ? 0.05).     

Comparison of Taiwan paddy- and upland-cultivated taro (Colocasia esculenta L.) cultivars for nutritive values

Taro (Colocasia esculenta L.), an important food staple for millions of people, is grown exclusively in the tropical and semitropical regions of the world. It is cultivated mainly in developing countries, rarely on large plantations but on small farms with little technology. The purpose of this study was to investigate the effect of cultivars and field preparations of taro corms on the nutrient content and protein nutritional quality. Three local cultivars of taro corms were grown by paddy and upland cultivation in Taiwan. The results showed that taro contained 63.6%–72.4% moisture, and upland-cultivated taro corms retained a higher moisture content compared to paddy taro. Results revealed that taro corms also contained 21.1%–26.2% starch and 1.75%–2.57% crude protein and provided total energy in the range of 97.1–118.3 kcal/100 g fresh taro. Taro corms had reasonably high contents of potassium and magnesium, whose ranges were 2251–4143 and 118–219 mg/100 g dry matter, respectively. Upland-cultivated taro tended to have higher mineral content than paddy taro. Taro corms are moderately good sources of water-soluble vitamins, such as thiamin, riboflavin and ascorbic acid, compared to other tropical roots. A higher soluble sugar content in upland-cultivated taro corms was found than in paddy taro. The cultivar Mein contained higher soluble fibre levels than two other cultivars. Total oxalate and phytic acid levels of taro corms were in the range of 234–411 and 139–169 mg/100 g dry matter, respectively, which included 60%–75% of water-soluble oxalate. Essential amino acid contents of taro proteins from both paddy and upland cultivation were fairly similar to the FAO reference pattern, except for the contents of sulfur-containing amino acids, tryptophan, and histidine.     

Tocols in caneberry seed oils

The compositional analysis of tocols in oils extracted from Korean caneberry seeds was compared with commercial soybean, corn, olive, canola, perilla, and grape seed oils. The oils from caneberry seeds of six different species were extracted using either a chloroform–methanol–water system or hot hexane. Tocols from all of the oils were analysed using isocratic HPLC. The contents of total tocopherols in the caneberry seed oils were about 75–290 mg/100 g oil, whereas tocotrienols were not detected. γ-Tocopherol was the most abundant tocopherol (31.8–239 mg/100 g oil) in the caneberry seed oils, followed by α-tocopherol (7.6–58.2 mg/100 g oil). The contents of total tocols in soybean, corn, olive, canola, perilla, and grape seed oils were 99.9, 61.1, 28, 27, 45.4, and 52.2 mg/100 g oil, respectively. Total tocol content was higher in most of the caneberry seed oils including the refined ones than in the commercial vegetable oils.     

Carotenoid composition and vitamin A activity of medicinally important green leafy vegetables

Carotenoid composition of green leafy vegetables (GLVs, n = 30) with medicinal value was analyzed by HPLC; vitamin A activity (as retinol equivalent, RE) of provitamin A carotenoids was calculated. Results show that among GLVs studied, the level of β-carotene (50–130 mg/100 g dry wt) was higher in nine GLVs than other carotenoids while lutein (50–187 mg/100 g dry wt) and zeaxanthin (1–5 mg/100 g dry wt) were higher in 12 GLVs than other xanthophylls. α-Carotene was detected only in nine GLVs, ranging from 1 to 37 mg/100 g dry wt. Interestingly, Chenopodium album, Commelina benghalensis and Solanum nigrum were found to contain higher levels of both lutein and β-carotene in the range of 84–187 and 50–115 mg/100 g dry wt, respectively. The values of retinol equivalents (RE) ranged from 641 to 19101 and were higher (>10,000) in six GLVs of the 30. The results demonstrate that GLVs studied contained higher levels of RE and lutein.     

Optimization of phenolics and dietary fibre extraction from date seeds

This work was conducted to optimise extraction conditions of phenolics and dietary fibre from date seeds. The effects of solvent to sample ratio, temperature, extraction time, number of extractions and solvent type on phenolic extraction efficiency were studied. At two-stage extraction, each stage 1 h duration at 45 °C with a solvent to sample ratio of 60:1, is considered optimum. Acetone (50%), and butanone were the most efficient solvents for extraction and purification, increasing the yield and phenolic contents of seed concentrate to 18.10 and 36.26 g/100 g, respectively. The total dietary fibre of seeds (57.87 g/100 g) increased after water and acetone extractions to 83.50 and 82.17 g/100 g, respectively. Nine phenolic acids (free and liberated) were detected in seeds with p-hydroxybenzoic (9.89 mg/100 g), protocatechuic (8.84 mg/100 g), and m-coumaric (8.42 mg/100 g) acids found to be among the highest. After extraction and purification, total phenolic acid content increased significantly from 48.64 to 193.83 mg/100 g. Protocatechuic, caffeic and ferulic acids were the major phenolic acids found in the concentrates. Based on this study, we believe date seed concentrates could potentially be an inexpensive source of natural dietary fibre and antioxidants and possibly used as a functional food ingredient.     

Quality characteristics of biscuits prepared from finger millet seed coat based composite flour

Finger millet seed coat is an edible material and contains good proportion of dietary fibre, minerals and phytochemicals. The seed coat matter (SCM) forms a by-product of millet milling, malting and decortication industries and can be utilised as composite flour in biscuit preparation. The SCM from native, malted and hydrothermally treated millet contained 9.5–12% protein, 2.6–3.7% fat and 40–48% dietary fibre, besides 3–5% polyphenols and 700–860 mg/100 g of calcium. The biscuits prepared using the composite flour were of crisp texture and exhibited breaking strength of 1480–1690 g compared to control biscuits (1560 g). The biscuits were of mild grey colour (ΔE = 40–50) and exhibited higher protein, dietary fibre and calcium contents. The sensory evaluation of the biscuits indicated that 10% of SCM from native and hydrothermally processed millet and 20% from malted millet could be used in composite biscuit flour.     

Chemical composition and non-volatile components of Croatian wild edible mushrooms

The chemical composition (dry matter, crude protein, crude fat, total carbohydrates, and ash) and non-volatile components content (soluble sugars, free amino acids, and 5′-nucleotides) of 10 popular Croatian wild edible mushroom species (Agaricus campestris, Boletus edulis, Calocybe gambosa, Cantharellus cibarius, Craterellus cornucopioides, Entoloma clypeatum, Flammulina velutipes, Macroleptiota procera, Morchella elata, and Pleurotus ostreatus) were determined. All investigated mushrooms were found to be good sources of proteins and total carbohydrates, with contents varying in the ranges of 27.95–38.89, and 42.62–66.78 g/100 g, respectively. In addition, the fat contents were very low 1.34–6.45 g/100 g. B. edulis (19.87 mg/g) showed the highest concentration of essential amino acids and M. elata (14.25 mg/g) the lowest concentration. Monosodium glutamate-like components and total flavour 5′-nucleotides were the highest in C. cornucopioides (45.85 and 13.88 mg/g, respectively), and lowest in F. velutipes (7.63 and 1.05 mg/g, respectively). Equivalent umami concentration values in 10 Croatian wild edible mushrooms ranged from 73.78 to 1186.45 g MSG/100 g dry weight, and overall, all these mushrooms possessed highly umami taste.     

Mineral content of tropical fruits and unconventional foods of the Andes and the rain forest of Colombia

A total of 68 species of starchy foods, tropical fruits, leaves and tubers (101 samples), were collected on the foothills of the Colombian Andes and in the rain forests of the Colombian Pacific coast. Their edible portion was analyzed for mineral content (Ca, P, Mg, K, Na, Cl, S, Mn, Zn, Fe, Cu, Se, Co, Ni). The foods were generally high in K (36–1.782 mg K/100 g edible portion) and low in sodium (<45 mg Na/100 g edible portion). The tree foliages had the highest contents in most of the elements, especially in calcium (280–1242 mg Ca/100 g edible portion, i.e., up to 62 g Ca/kg dry matter) and iron (0.7–8.4 mg Fe/100 g edible portion). Correlations (P < 0.001) were observed between total ash and many elements, especially Ca and Mg (r =  0.77 and 0.73, respectively). High correlations were also obtained between Ca and Mg (r = 0.93).     

Near-infrared spectroscopic analysis of macronutrients and energy in homogenized meals

Near-infrared (NIR) reflectance spectroscopy was evaluated as a rapid and environmentally benign technique for the simultaneous determination of macronutrients and energy in commercially available, packaged meals. Reflectance spectra (400–2498 nm) of homogenized meals were obtained with a dispersive NIR spectrometer. Protein and moisture were measured by AOAC reference methods, total fat by a semi-automated acid hydrolysis, solvent extraction, gravimetric method and total carbohydrate calculated. Energy was calculated using Atwater factors. Using multivariate analysis software, PLS models (n = 113–115 products) were developed to relate NIR spectra of homogenized meals to the corresponding reference values. The models predicted components and energy in validation samples (n = 37–38 products), overall, with r² of above 0.96. Ratios of deviation to performance were between 3.6 and 6.6, and indicated adequacy of the models for screening, quality control, or process control. Performance of the models varied substantially when used to predict sub-groups of meals within the validation set.     

Indigestible fraction of okara from soybean: composition,physicochemical properties and in vitro fermentability by pure cultures of <Emphasis Type="Italic">Lactobacillus acidophilus</Emphasis> and <Emphasis Type="Italic">Bifidobacterium bifidum</Emphasis>

Major non-digestible components of soybean seeds and okara were determined by an in vitro enzymatic-physiological method, alternative to dietary fibre. Total indigestible fraction was higher in okara (41.6%) than in seeds (28.5%), and consisted of soluble and insoluble fractions, mainly composed of non-starch polysaccharides, klason lignin and resistant protein. Total protein was lower in okara (32.29%) than in seeds (46.97%), as were oil (14.72% okara–20.89% seeds) and ash contents (3.18% okara–4.60% seeds). In vitro digestibility of protein was lower for okara (84.3%), than for soybean seed (91.8%). Moreover, okara showed high swelling (10.54 ± 0.14 mL/g d.w.) and water retention capacity (8.87 ± 0.06 g/g d.w.) and was fermented in vitro to a greater extent by Bifidobacterium bifidum (29.8%), than by Lactobacillus acidophilus (8.3%). For its composition, physico-chemical properties and bifidogenic capacity in vitro, okara is a potential candidate to be a prebiotic fibre-rich ingredient of new functional foods.     

Effect of cooking and sterilisation on the composition of amino acids in immature seeds of flageolet bean (Phaseolus vulgaris L.) cultivars

The aim of the work was to evaluate the amino acid content and protein quality in products of immature bean seeds with a dry matter content of 40%. The investigation included raw seeds, fresh seeds after cooking to consumption consistency and seeds after canning. Raw seeds of the cultivar Alamo contained more amino acids in 100 g fresh matter than the seeds of the cultivars Flaforte and Mona. Cooking and sterilisation brought about decreases in the content of all the amino acids in the investigated cultivars; 1–50% and 9–60% respectively. Higher losses being noted in sterilised seeds. If the results were expressed in 16 g N, the differences in amino acid content were much smaller. The amino acid content of Mona was lower than that of the remaining cultivars. The cooking of seeds did not bring about changes in relation to the raw material (except tyrosine which showed a decrease 35–45%); however, sterilisation affected the content of most amino acids (from −45 to +17%). Compared with the standard (FAO/WHO/UNU, 2007), the limiting amino acid was cystine with methionine (amino acid score 70–83). Of the seeds prepared for consumption, sterilised bean seeds had a higher EAA index value, while of the cultivars, the seeds of Alamo had the highest value (147–162).     

Identification and characterisation of low-molecular-weight phenolic compounds in bayberry (Myrica rubra Sieb. et Zucc.) leaves by HPLC-DAD and HPLC-UV-ESIMS

Leaves of each of two bayberry cultivars, Biqi and Dongkui, were divided into three categories by age, namely immature, intermediate, and mature. Phenolic compounds were analysed by the methods of HPLC-DAD and HPLC-UV-ESIMS. Gallic acid and EGCG were identified positively, and 13 other compounds (flavan-3-ol monomers, prodelphinidin oligomers, and flavonol glycosides) were partially identified. Gallic acid (7.5–87.8 mg/100 g) was the only phenolic acid detected and flavan-3-ols were abundant. Myricetin deoxyhexoside (535.4–853.0 mg/100 g) was the major flavonol glycoside. Among the three categories, immature leaves of both cultivars recorded the highest level of total phenolics, irrespective of whether they were measured by the Folin–Ciocalteu method (19404.0 mg/100 g in Biqi and 19626.0 mg/100 g in Dongkui) or as the sum of individual phenolic compounds (2255.9 mg/100 g in Biqi and 1797.1 mg/100 g in Dongkui). The results showed that bayberry leaves are a potentially rich source of beneficial phenolics.