Chemical and nutritional evaluation of two amaranth (Amaranthus cruentus)-based infant formulas

The objective of this study was to calculate, prepare and evaluate the Protein Efficiency Ratio (P.E.R.) and Net Protein Utilization (N.P.U.) of two infant formulas made with amaranth (Amaranthus cruentus). Both formulas were formulated to match a previously developed and tested soy-oats infant formula. No significant differences were found between the three formulas with respect to corrected Protein Efficiency Ratio (P.E.R.) and Net Protein Utilization (N.P.U.) values. Only the product made with the 1-R fraction of amaranth was found to have a significantly lower P.E.R. than casein.Paper presented at the Annual Convention of the Institute of Food Technologists, Anheim, California, U.S.A., June, 1990.     

Improving effect of lyophilization on functional properties of resistant starch preparations formed by acid hydrolysis and heat treatment

In this study, effects of lyophilization on the functional properties of acid modified and autoclaved corn starch preparations were investigated. RS contents and pasting properties of these starch preparations were also determined. Significant increases in solubility were observed as the hydrolysis level of the lyophilized samples increased. All of the acid-modified gelatinized–autoclaved–lyophilized samples had higher water binding values than those of native starch and heat treated oven-dried native starch. Acid-modified gelatinized–autoclaved–lyophilized samples (with storage at 95°C: GASL or without storage: GAL, before lyophilization) improved emulsion properties of soy protein solution significantly. Acid modification seems to be a prerequisite to achieve improving effect of lyophilization. While native starch did not contain any RS, the level increased to 8.1% due to gelatinization, autoclaving and oven-drying (Control 2). The RS content of Control 2 was higher than that of gelatinized–autoclaved–lyophilized native starch (N-GAL, 2.9%). The samples stored prior to lyophilization had higher RS contents as compared to the corresponding unstored samples. The highest RS content (12.4%) was observed in 2h-GASL sample. Cold viscosity was observed in the RVA curves of N-GASL, 2h-GASL, N-GAL and 2h-GAL samples. A possible mechanism/model is suggested to explain the lack or existence of a cold viscosity.     

In vitro starch digestibility and predicted glycaemic indexes of buckwheat,oat, quinoa,sorghum, teff and commercial gluten-free bread

The in vitro starch digestibility of five gluten-free breads (from buckwheat, oat, quinoa, sorghum or teff flour) was analysed using a multi-enzyme dialysis system. Hydrolysis indexes (HI) and predicted glycaemic indexes (pGI) were calculated from the area under the curve (AUC; g RSR/100g TAC*min) of reducing sugars released (RSR), and related to that of white wheat bread. Total available carbohydrates (TAC; mg/4 g bread “as eaten”) were highest in sorghum (1634 mg) and oat bread (1384 mg). The AUC was highest for quinoa (3260 g RSR), followed by buckwheat (2377 g RSR) and teff bread (2026 g RSR). Quinoa bread showed highest predicted GI (95). GIs of buckwheat (GI 80), teff (74), sorghum (72) and oat (71) breads were significantly lower. Significantly higher gelatinization temperatures in teff (71 °C) and sorghum flour (69 °C) as determined by differential scanning calorimetry (DSC) correlated with lower pGIs (74 and 72). Larger granule diameters in oat (3–10 μm) and sorghum (6–18 μm) in comparison to quinoa (1.3 μm) and buckwheat flour (3–7 μm) as assessed with scanning electron microscopy resulted in lower specific surface area of starch granules. The data is in agreement with predictions that smaller starch granules result in a higher GI.     

小麦叶片表皮蜡质成分及含量分析

为了解小麦叶片表皮蜡质晶体结构及成分,以具有白霜状表型的小麦品系310为材料,在抽穗期选取小麦倒二叶,用扫描电镜观察叶片蜡质晶体结构,并采用气相色谱/质谱(GC-MS)分析其蜡质组分,以峰面积为指标,定量计算各蜡质组分的含量。结果表明,小麦叶片上表皮的蜡质晶体呈现致密的片状结构,下表皮呈现管状结构。抽穗期叶片的蜡质总含量为9.204±0.650μg·cm-2。其中,脂肪醇含量最高,为3.690±0.485μg·cm-2,占蜡质总量的40.37%;烷烃次之,含量为3.040±0.678μg·cm-2,占蜡质总量的32.88%;醛、酸、二酮分别为0.524±0.032μg·cm-2、0.469±0.040μg·cm-2、0.951±0.064μg·cm-2,分别占蜡质总量的5.65%、5.18%和7.12%;未鉴定出的成分为0.815±0.140μg·cm-2,占蜡质总量的8.79%。在叶片表皮蜡质总化合物中,C28醇分布最多,占化合物总量的32.16%;其次为C29烷烃,占化合物总量的18.72%。     

Modifications of physicochemical and functional properties of amaranth protein isolate (Amaranthus cruentus BRS Alegria) treated with high-intensity ultrasound

The present study investigated the effects of high-intensity ultrasound (HIUS) on the physicochemical and functional properties of amaranth protein isolates (API). Aqueous dispersions of API (10%) were continuously treated for 15 or 30 min with ultrasound equipment (100 W, 30 kHz) at 30, 60, and 90% amplitudes. The electrophoresis technique demonstrated no changes in the molar masses of the proteins. However, HIUS significantly increased the surface free sulfhydryl groups (SH) and changed the surface hydrophobicity, indicating a breakdown of internal links that maintained the native API structure. Ultrasound reduced the size of the particles in the aqueous dispersions of API, suggesting the dissociation of aggregates from API. The results showed that the solubility in most HIUS-treated API was significantly (p < 0.05) higher than that of the native proteins at pH 7. The energy density of 50 J/cm³ provided the best-combined properties of emulsion formation and stability. These results suggest that HIUS is a useful technology to improve the functional properties of amaranth proteins.     

Effect of emulsifiers on complexation and functional properties of oxidized white sorghum (Sorghum bicolor) starch

The effect of addition of three commonly used emulsifiers namely GMS (glycerol monostearate), SSL (sodium stearoyl lactylate) and DATEM (diacetyl tartaric acid esters of monoglycerides) on complexation, thermal, pasting and textural properties of OWSS (oxidized white sorghum starch) was studied. The study is of interest as both oxidized starches and emulsifiers are present as co-ingredients in different food products and thus their complexation could affect the textural characteristics of foods. The complexation index (CI) reduced on oxidation of sorghum starch. The CI for native white sorghum starch (NWSS) was in the order GMS > SSL > DATEM whereas for OWSS, CI was in the order GMS > SSL > DATEM. Presence of emulsifiers significantly reduced gelatinization enthalpies of starches. Types I and II amylose–lipid complexes were observed in NWSS and OWSS on addition of GMS. Pasting temperature of NWSS increased while peak viscosity reduced on addition of SSL and GMS. Cold paste and setback viscosities of OWSS increased significantly (p ≤ 0.05) on addition of emulsifiers. Emulsifiers reduced firmness and rupture strength of NWSS and OWSS gels. Increase in firmness of gels on storage increased in NWSS and decreased in OWSS on addition of emulsifiers. Elasticity of OWSS on cold storage was higher in the presence of SSL and GMS.     

Effects of heat,drought and their combined effects on morphological structure and physicochemical properties of rice (Oryza sativa L.) starch

High temperature (HT) and drought stress (WS) severely affect rice quality by altering the starch structure in rice. The morphological and physicochemical properties of starches isolated from two rice varieties grown under three stress treatment (HT, WS and WS + HT) during the grain filling stage were investigated. The results showed that WS increased amylose content (AC%) and the proportion of large starch granules (LSG) and made the surface of the starch granule smooth and flat. As a result, a lower relative crystallinity, surface order, swelling power, setback viscosity and gelatinization enthalpy were caused. HT decreased AC% and milled rice rate, but increased chalky rice rate, the number of LSG and the large air space and pits on the surface of the starch granules. As a result, a higher relative crystallinity, surface order, swelling power, setback viscosity and gelatinization enthalpy were caused. Similar results were observed under the treatment of WS + HT, indicating that there is a mild antagonistic effect on rice starch when the HT and WS occur simultaneously.     

Properties of thermoplastic starch from cassava bagasse and cassava starch and their blends with poly (lactic acid)

Cassava bagasse is an inexpensive and broadly available waste byproduct from cassava starch production. It contains roughly 50% cassava starch along with mostly fiber and could be a valuable feedstock for various bioproducts. Cassava bagasse and cassava starch were used in this study to make fiber-reinforced thermoplastic starch (TPS_B and TPS_I, respectively). In addition, blends of poly (lactic acid) and TPS_I (20%) and TPS_B (5, 10, 15, 20%) were prepared as a means of producing low cost composite materials with good performance. The TPS and PLA blends were prepared by extrusion and their morphological, mechanical, spectral, and thermal properties were evaluated. The results showed the feasibility of obtaining thermoplastic starches from cassava bagasse. The presence of fiber in the bagasse acted as reinforcement in the TPS matrix and increased the maximum tensile strength (0.60 MPa) and the tensile modulus (41.6 MPa) compared to cassava starch TPS (0.40 and 2.04 MPa, respectively). As expected, blending TPS with PLA reduced the tensile strength (55.4 MPa) and modulus (2.4 GPa) of neat PLA. At higher TPS_B content (20%) the maximum strength (19.9 MPa) and tensile modulus (1.7 GPa) were reduced about 64% and 32%, respectively, compared to the PLA matrix. In comparison, the tensile strength (16.7) and modulus (1.2 GPa) of PLA blends made with TPS_I were reduced 70% and 51% respectively. The fiber from the cassava bagasse was considered a filler since no increase in tensile strength of PLA/TPS blends was observed. The TPS_I (33.1%) had higher elongation to break compared to both TPS_B (4.9%) and PLA (2.6%). The elongation to break increased from 2.6% to 14.5% by blending TPS_I with PLA. In contrast, elongation to break decreased slightly by blending TPS_B with PLA. Thermal analysis indicated there was some low level of interaction between PLA and TPS. In PLA/TPS_B blends, the TPS_B increased the crystallinity of the PLA component compared to neat PLA. The fiber component of TPS_B appeared to have a nucleating effect favoring PLA crystallization.     

Compositional,functional and storage properties of flours from raw and heat processed African breadfruit (Treculia africana Decne) seeds

African breadfruit (Treculia africana Decne) seeds were either boiled or roasted and then milled into flour. Chemical composition, functional properties and storage characteristics of raw and treated flours and the effect of partial proteolysis on selected functional properties of the raw flour were determined. Raw flour contained 20.1% crude protein, 2.5% total ash and 13.7% fat. Heat processing significantly (p<0.05) improved in vitro protein digestibility, and water and fat absorption capacities but decreased bulk density, nitrogen solubility, emulsion and foaming properties, trypsin inhibitor, and phytic acid and polyphenol contents of the samples. Boiling proved more effective than roasting for improving protein digestibility, emulsion capacity and foam stability and reducing antinutritional factor levels. Partial proteolysis increased nitrogen solubility, bulk density and water and fat absorption capacities but decreased foam capacity at hydrolysis levels greater than 35%. Fatty acid and peroxide values of the samples increased during storage. Compared to raw samples, heat processed samples had significantly (p<0.05) lower and more acceptable peroxide values and free fatty acid contents and higher and more stable water (3.0 g/g sample) and fat (2.4 g/g sample) absorption capacities.     

Improved functional properties of pasta: Enrichment with amaranth seed flour and dried amaranth leaves

The present investigation evaluated the effects of dried amaranth leaves (DAL) and amaranth seed flour (AF) as ingredients for pasta production and their contribution to antioxidant activity. Cooking quality, proximal and aroma analysis, antioxidant capacity and sensory evaluations were performed. The results demonstrated that pastas with amaranth ingredients had decreased cooking time, increased cooking loss percentage, and decreased luminosity values compared with semolina control pasta. Pastas with both AF and DAL demonstrated the highest protein, crude fiber and ash contents. The addition of DAL resulted in higher contents of iron, zinc, magnesium and potassium compared with the control pasta. TC, FRAP and ORAC assays showed that the pastas exhibited an important reduction in antioxidant capacity by cooking process. Formulas with DAL showed the higher antioxidant capacity values after cooking. The addition of AF and DAL has proved to increase the functional benefits of the pasta.     

Near infrared spectra indicate specific mutant endosperm genes and reveal a new mechanism for substituting starch with (1→3,1→4)-β-glucan in barley

Near Infrared Reflectance spectroscopy was tested as a screening method to characterise high lysine mutants from a barley collection by classification through Principal Component Analysis (PCA). Mean spectra of the samples within each cluster identified gene-specific patterns in the 2270–2360 nm region. The characteristic spectral signatures representing the lys5 locus (Risø mutants 13 and 29) were found to be associated with large changes in percentage of starch and (1→3,1→4)-β-glucan. These alleles compensated for a low level of starch (down to 30%) by a high level of (1→3,1→4)-β-glucan (up to 15–20%), thus, maintaining a constant production of polysaccharides at 50–55%, within the range of normal barley.The spectral tool was tested by an independent data set with six mutants with unknown polysaccharide composition. Spectral data from four of these were classified within the high (1→3,1→4)-β-glucan BG lys5 cluster in a PCA. Their high (1→3,1→4)-β-glucan and low starch content was verified. It is concluded that genetic diversity such as from gene regulated polysaccharide and storage protein pathways in the endosperm tissue can be discovered directly from the phenotype by chemometric classification of a spectral library, representing the digitised phenome from a barley gene bank.     

Characterisation of starch during germination and seedling development of a rice mutant with a high content of resistant starch

To acquire a better understanding of whether RS influences the dynamics of in vivo starch digestion and seed vigour, the high-RS rice mutant RS4 (RS ca. 10%) and the wild type R7954 were used to investigate total amylase activity, seedling vigour, starch content and starch granule structure during germination. RS4 exhibited similar seed vigour to R7954. Amylose and amylopectin in R7954 showed synchronous degradation throughout the whole process, while amylopectin was hydrolysed significantly faster than amylose in RS4 during the earlier germination stages. The starch residues of RS4 after germination (GD) lost endotherm peaks and showed a special X-ray diffraction pattern with only two peaks at around 16.90° and 21.62°, probably due to remnants of amylopectin and its tight crosslinking with the cell wall. The remaining starch after 10 GD, primarily amylopectin may make a critical contribution to total resistant starch content. These results indicated that RS had no negative impact on seed vigour in rice lines, although RS cannot be hydrolysed by α-amylase from human and animal in vitro. By appropriately increasing the special amylopectin fraction, a new breeding programme of high RS crops and improvement in the eating quality of high RS rice varieties might be achieved.     

An evaluation of the effect of Bacillus cells and Bacillus spores in association with cowpea granules as starter cultures for the fermentation of African oil bean (Pentaclethra macrophylla Bentham) to `ugba'

Studies on the improvement of the traditional production of `ugba',a protein-rich fermented African oil bean seed product, were undertaken,by developing starter cultures of Bacillus subtilis cells andspores in association with cowpea granules. The viability of the cellsin association remained stable at 94.5% for 6 months at 30 <sup>°</sup>C and for up to 10 months at 4 <sup>°</sup>C while the viability of the sporesin association remained stable at ca. 96% for up to 10 months at both4 and 30 <sup>°</sup>C. The starter cultures resulted in high increases inprotease activity from ca 2.8 mg N/min to about 51.6 ± 0.4 mg N/minin 48 h and a corresponding increase in amino-nitrogen content of ca2.0 ± 0.2 mg N 100 g dry matter (DM) to ca 18.5 ± 0.3 mg N/100g (DM) during the same period. Changes in the protease activity of thenatural process were gradual and increased from 3.0 mg N/min to 38.0 ±0.8 mg N/min after 5 days of fermentation. The maximum amino nitrogencontent of `ugba' produced by the starter cultures (18.5 ± 0.3 mgN/100 g DM) after 2 days was significantly (p < 0.05) higher than themaximum amino nitrogen content (12.5 ± 0.8 mg N/100 g DM), of `ugba'obtained by the natural process. `Ugba' produced by the starter cultureswere well accepted and compared favorably with the natural product.     

In vitro starch digestibility and predicted glycaemic indexes of buckwheat,oat, quinoa,sorghum, teff and commercial gluten-free bread

The in vitro starch digestibility of five gluten-free breads (from buckwheat, oat, quinoa, sorghum or teff flour) was analysed using a multi-enzyme dialysis system. Hydrolysis indexes (HI) and predicted glycaemic indexes (pGI) were calculated from the area under the curve (AUC; g RSR/100g TAC*min) of reducing sugars released (RSR), and related to that of white wheat bread. Total available carbohydrates (TAC; mg/4 g bread “as eaten”) were highest in sorghum (1634 mg) and oat bread (1384 mg). The AUC was highest for quinoa (3260 g RSR), followed by buckwheat (2377 g RSR) and teff bread (2026 g RSR). Quinoa bread showed highest predicted GI (95). GIs of buckwheat (GI 80), teff (74), sorghum (72) and oat (71) breads were significantly lower. Significantly higher gelatinization temperatures in teff (71 °C) and sorghum flour (69 °C) as determined by differential scanning calorimetry (DSC) correlated with lower pGIs (74 and 72). Larger granule diameters in oat (3–10 μm) and sorghum (6–18 μm) in comparison to quinoa (1.3 μm) and buckwheat flour (3–7 μm) as assessed with scanning electron microscopy resulted in lower specific surface area of starch granules. The data is in agreement with predictions that smaller starch granules result in a higher GI.     

Effects of amylose content,cooling rate and aging time on properties and characteristics of rice starch gels and puffed products

This study aimed at investigating the effects of amylose content (AC) of 0.12–19.00% w/w on dry basis, cooling rate (1, 3, 5, and 9 °C/min), and aging time (24, 48, and 72 h) on structure, physical properties and sensory attributes of rice starch-based puffed products. They had an influence upon the crystalline type, and the relative crystallinity (RC). The thermal and physical properties of starch gels were also determined. Amorphism was found for starch gels with 0.12% AC. The polymorphisms (B and V) and differential scanning calorimetric endotherms were found for those with AC ≥4.00%. The RC, retrogradation enthalpy (ΔH_r) and gel hardness increased with AC and aging time. The cooling rate did not affect RC, but increased ΔH_r and gel hardness. The higher AC and aging time resulted in higher hardness, fracturability, crispiness and bulk density, but lower expansion ratio and less oiliness of the puffed products. The hardness, fracturability, crispiness and bulk density of puffed products were well correlated with the RC of starch gel.     

Changes in the thermal and structural properties of maize starch during nixtamalization and tortilla-making processes as affected by grain hardness

The objective of this work was to evaluate the changes in the thermal and structural properties of maize starch during nixtamalization and the tortilla-making process and their relationship with grain hardness. Three maize types with varying hardness (hard, intermediate, soft) were processed by three nixtamalization processes (classic, traditional and ecological). Starch from the three maize types showed an A-type pattern and two endotherms corresponding to gelatinization and melting of the Type I amylose-lipid complexes. After cooking and steeping, in intermediate and soft grains the partial gelatinization and the annealing affected the starch properties and promoted the formation of amylose-lipid complexes. These effects were not observe in hard grains. The increase in melting enthalpy and the intensity of the peak 2θ∼20° from nixtamal to tortillas demonstrated the formation of amylose-lipid complexes. A third endotherm above 114 °C in some treatments of nixtamal and tortilla starch demonstrated the transformation of some amylose-lipid complexes in a most ordered structures (Type II complexes). The V-type polymorph structure found in native starch, nixtamal, and tortilla corresponds to a coexistence of Type I and Type II complexes. Formation of amylose-lipid complexes in tortillas had a partial effect on decreasing starch retrogradation (r = −0.47, P < 0.05).