Corn fiber gum: New structure/function relationships for this potential beverage flavor stabilizer

Corn fiber arabinoxylan is a hemicellulose B isolated from the fibrous portions (pericarp, tip cap, and endosperm cell wall fractions) of corn kernels by alkaline solution, often in the presence of hydrogen peroxide and is commonly referred to as “Corn fiber gum” (CFG). The unique polysaccharide, CFG, with its low solution viscosity has been proposed as a good stabilizer for oil-in-water emulsions and we have verified that in some model systems, it can out-perform the “gold standard” emulsifier, gum arabic. But the precise mechanism for the stabilization of oil-in-water emulsion is not well understood due to its structural and molecular complexity. It is unclear and even puzzling how a water-soluble, hydrophilic arabinoxylan could function as an emulsifier, since most emulsifiers have hydrophobic as well as hydrophilic surfaces and regions on the molecule. To understand the structural properties of CFG that may be responsible for its emulsifying properties, we have prepared a number of purified and modified CFG samples from different sources of corn fiber. We then studied their detailed structures and measured their ability to stabilize oil-in-water emulsions. The results show that “pure” CFG fractions often contain minor, but perhaps functionally important amounts of associated lipids and proteins. Understanding the critical structural elements required for optimal emulsification properties will allow future commercial producers of CFG to provide consistent quality and functionality in their products.     

Structural characteristics and in vitro digestibility of Mango kernel starches (Mangifera indica L.)

Structural characteristics and digestibility of starches isolated from the kernels of two mango cultivars (Chausa and Kuppi) were studied and compared with those of a commercial normal corn starch. Mango kernel starches showed an A-type X-ray diffraction pattern, with relative crystallinities of 35.4% and 38.3%, respectively for Kuppi and Chausa cultivars. The structural characterisation obtained, using high performance size exclusion column chromatography connected to multi-angle laser light scattering and refractive index detectors (HPSEC-MALLS-RI), revealed that the mango kernel starches had lower molecular weight (M_w) and radius of gyration (R_g) of amylopectin and amylose compared to those of corn starch. The M_w of amylopectin for Chausa and Kuppi starches were 179 × 10⁶ and 140 × 10⁶ g/mol, respectively. The amounts of readily digestible starch (RDS) and slowly digestible starch (SDS) were lower for mango kernel starch than those of corn starch. Resistant starch (RS) contents in the mango kernel starches (75.6% and 80.0%, respectively) were substantially higher than those of corn starch (27.3%). The glycemic index (GI) values for mango kernel starches were 48.8 and 50.9 (for Chausa and Kuppi, respectively), whereas that of corn starch was 74.8, indicating that the mango kernel starch granules were highly resistant to digestion with significant contents of RS.     

Effects of chemical composition variation on the dynamics of ruminal fermentation and biological value of corn milling (co)products

The objectives of this study were to evaluate the dynamics of gas production of several corn (co)products, to develop equations to predict the rate of ruminal fiber digestion, to estimate total digestible nutrients (TDN) and net energy for lactation (NE_L), and to assess the stochasticity of chemical composition and nutritive value variability. Four corn milling (co)products were evaluated in this study: high protein dried distillers grains (HP-DDG), corn bran (BRAN) and dehydrated germ (GERM), and a dried distillers grains plus soluble produced with a low-heat drying process (BPX). Alfalfa hay was used as an internal standard feed in the in vitro fermentation dynamics analysis. Standard chemical analyses, in vitro digestibility, and in vitro gas production techniques were used to obtain the necessary physicochemical characterization of feeds. The in vitro dry matter digestibility at 24 and 48 h of incubation decreased exponentially as acid detergent insoluble nitrogen increased. However, the degree of in vitro dry matter digestibility reduction was more accentuated at 24 than at 48 h of incubation. The difference among these feeds regarding the dynamics of the anaerobic fermentation within different substrates (intact feed, and fiber and defatted residues) was evaluated. Results suggested that the proportion of fiber digested in the rumen was affected by the degree of sample processing and fat removal. Fractional fermentation rate (kf) of neutral detergent residue (without sodium sulfite) and defatted fiber residue for BRAN, GERM, HP-DDG, and BPX was estimated to be 0.0635 and 0.0852 h⁻¹, 0.0803 and 0.0914 h⁻¹, 0.118 and 0.117 h⁻¹, and 0.0695 and 0.0844 h⁻¹, respectively. The most influential variables affecting kf_NDR of HP-DDG and BPX also affected the predicted TDN, suggesting that fiber quality is essential to ensure higher TDN values for these feeds. Our study indicated that it is possible to routinely quantify the rate of fiber digestion and this approach may be based on common analytical procedures namely estimates of neutral detergent fiber, acid detergent fiber, acid detergent insoluble nitrogen, ether extract, and acid detergent lignin. Our simulations of TDN values demonstrated that differences in fermentability and chemical composition of these corn (co)products might considerably affect the supply of energy to lactating dairy cow. The analytical methods developed in this study may serve as a valuable tool to assess nutrient quality and uniformity when samples differ in chemical composition.     

Molecular mass distribution of dextran in Brazilian sugar and insoluble deposits of cachaça

The dextran molecular mass distribution profile in 77 sugar samples from Brazil and twelve insoluble deposits (alcoholic flocks) samples from sugared cachaças (Brazilian sugar cane spirit) is described in terms of number-average molecular mass M_n, weight-average molecular mass M_w, Z-average molecular mass M_z, and polydispersity. The analyses were performed by size-exclusion chromatography, using a refractive index detector. In most of the sugar samples, it was possible to identify two major groups of dextrans with M_w averages of 5 × 10⁶ and 5 × 10⁴ Da. Based on the evaluated parameters, the dextran distribution profile is about the same in samples analyzed over five seasons, and, therefore, it is likely that the Brazilian product pattern will not change very much over the years. In insoluble deposits from sugared cachaças, dextrans with M_w values in the order of the 10⁵ Da were the most frequent ones, being present in 58% of the samples.     

Distribution of zearalenone in malted barley fractions dependent on Fusarium graminearum growing conditions

Zearalenone (ZON) distribution was measured in main fractions of malted barley, dependent on incubation time (17, 26, 34 days), water activity (0.95 and 0.98) and temperature (20 °C and 30 °C). Malted samples were sterilised and inoculated with Fusarium graminearum. ZON levels were higher (p < 0.01) in bran and germ than flour under almost all growing conditions. Incubation at 30 °C resulted in generally lower ZON levels in germ and bran, regardless of a_w and incubation time. After 34 days, ZON levels in flour from samples that were incubated at the higher temperature rose significantly. At 20 °C ZON concentration showed a bell-shaped concentration profile with increasing incubation time in bran and germ, whilst ZON levels in flour increased at a_w 0.98 and dropped at the lower a_w. The results indicate the importance of storage conditions for ZON levels in commercially relevant grain fractions of malted barley and help predict existing mycotoxin levels or manipulate storage conditions to reduce ZON content.     

EFFECT OF PARTICLE SIZE ON THE WATER SORPTION PROPERTIES OF CEREAL FIBERS1

Six particle size fractions were prepared by grinding and sieving stabilized hard red wheat bran, oat fiber, and corn bran. Water adsorption indices (WAI's) and effective diffusion coefficients (D_eff) were measured for all size fractions. WAI's of wheat bran decreased with particle size. WAI's of oat bran increased as particle size decreased and the WAI's of corn bran fractions did not vary as much as the other fibers. The D_eff's of wheat increased, of oat decreased, and of corn were about the same as the particle size decreased. The wheat D_eff was less than that of corn which was less than that of oats. Monolayer moisture content and bulk moisture content at high A_w were determined from moisture sorption isotherms measured on the smallest particles. There was no difference in the monolayer moistures but both corn and wheat brans adsorbed much more water at high A_w than did the oat bran. Effect of particle size on water sorption and, by inference, some types of functionality cannot be generalized and must be determined for each type of fiber.     

Effect of selected Hofmeister salts on textural and rheological properties of nonfat cheese

Three Hofmeister salts (HS; sodium sulfate, sodium thiocyanate, and sodium chloride) were evaluated for their effect on the textural and rheological properties of nonfat cheese. Nonfat cheese, made by direct acidification, were sliced into discs (diameter = 50 mm, thickness = 2 mm) and incubated with agitation (6 h at 22°C) in 50 mL of a synthetic Cheddar cheese aqueous phase buffer (pH 5.4). The 3 HS were added at 5 concentrations (0.1, 0.25, 0.5, 0.75, and 1.0 M) to the buffer. Post-incubation, cheese slices were air dried and equilibrated in air-tight bags for 18 h at 5°C before analysis. Small amplitude oscillatory rheology properties, including the dynamic moduli and loss tangent, were measured during heating from 5 to 85°C. Hardness was determined by texture profile analysis. Acid-base buffering was performed to observe changes in the indigenous insoluble (colloidal) calcium phosphate (CCP). Moisture content decreased with increasing HS concentration. Cheeses incubated in high concentrations of SCN⁻ softened earlier (i.e., loss tangent = 1) compared with other HS treatments. Higher melting temperature values were observed for cheeses incubated in high concentrations of SO₄²⁻. Hardness decreased in cheeses incubated in buffers with high concentrations of SCN⁻. The indigenous CCP profile of nonfat cheese was not greatly affected by incubation in Cl⁻ or SCN⁻, whereas buffers with high concentrations of SO₄²⁻ reduced the acid-base buffering contributed by CCP. The use of high concentrations (1.0 M) of SCN⁻ for incubation of cheeses resulted in a softer protein matrix at high temperatures due to the chaotropic effect of SCN⁻, which weakened hydrophobic interactions between CN. Cheese samples incubated in 1.0 M SO₄²⁻ buffers exhibited a stiffer protein matrix at high temperatures due to the kosmotropic effect of SO₄²⁻, which helped to strengthen hydrophobic interactions in the proteins during the heating step. This study showed that HS influenced the texture and rheology of nonfat cheese probably by altering the strength of hydrophobic interactions between CN.     

Effect of water activity and temperature on degradation of 5′-inosine monophosphate in a meat model system

The influence of water activity (a_w) (0.7,0.8 and 0.9) and temperature (80° and 120 °C) on the degradation of meat flavor precursor inosine monophosphate (IMP) was studied in a meat fiber model system. Breast and leg muscle from Indian domesticated layer chicken (Gallus gallus) were washed repeatedly with 0.1 mol/l phosphate buffer of pH 6 to obtain pigment free and with minimum content of natural IMP in muscle fiber. The freeze-dried breast and leg meat fiber had a protein content of 86.5±0.48% and 85.6±0.50%, respectively. The IMP contents (mg/100 g) of leg muscle fiber (7.3±0.60) was higher (P?0.05) than in the breast meat fiber (5.1±1.20). The degradation of IMP was temperature-dependent (P?0.05) in both types of meat fiber systems. In the samples of a_w 0.8, the IMP degradation in breast meat fiber system was lower (P?0.05) than in a_w at 0.7 and 0.9 samples, when treated at 80 °C, whereas, there was no significance difference (P>0.05) in the degradation of IMP at a_w 0.7 and 0.9 when heated at 120 °C. The degradation of IMP in leg meat fiber model system at higher a_w (0.9) was more (P?0.05) as compared to lower a_w (0.7 and 0.8) at 80 °C, while the samples treated at 120 °C, the degradation of IMP at a_w 0.8 and 0.9 was more (P?0.05) than at a_w 0.7.     

Some functional properties of oat bran protein concentrate modified by trypsin

Oat bran protein concentrate (OBPC) was prepared from oat bran, and hydrolyzed using trypsin. Protein hydrolysates of three different degrees of hydrolysis (4.1%, 6.4% and 8.3% respectively) were obtained. SDS-PAGE analysis demonstrated that oat globulin was the major protein component in OBPC. After trypsin treatment, acidic polypeptides were partly degraded into large peptides (M_r = 29,000–33,000) and small peptides (M_r < 20,000); however, basic polypeptides were almost intact. The functional properties of the resulting products were compared with those of control OBPC. Marked changes in the protein functionality were caused by proteolysis. The solubility, water-holding capacity, emulsifying activity and foaming ability of the hydrolysates gradually increased with the increase in DH. However, the oil-holding capacity, emulsifying stability and foaming stability of the hydrolysates reduced to a certain extent.     

Determination of physicochemical properties of sulphated fucans from sporophyll of Undaria pinnatifida using light scattering technique

The weight average molecular weight (M_w) of the intact sulphated fucans extracted with water from the sporophyll of Undaria pinnatifida without acid treatment was determined using the high performance size exclusion chromatography coupled to multiangle laser light scattering and refractive index detection (HPSEC-MALLS-RI) system. The effects of different heating conditions on the determination of M_w were investigated. The extracted intact fucoidans mostly consisted of carbohydrates (54.9%) and sulphate (41.5%) with monosaccharide composition of 78.8% fucose and 21.2% galactose. The M_w of the intact fucoidans was reduced from 23,600 to 5200 kDa when heated in boiling water for 1–15 min. Microwave heating for 30 s decreased the M_w of fucoidans to 2400 kDa despite no significant polymer degradation. The results indicate that the 30 s-microwave heating yielded a more accurate M_w value of the intact fucoidans than any other heat treatments used in this study.     

玉米纤维胶-乳清分离蛋白Maillard共聚物对姜黄素乳液稳定性和消化特性的影响

以玉米纤维胶（corn fiber gum,CFG）、乳清分离蛋白（whey protein isolate,WPI）为基质制备Maillard反应产物,探究不同热处理时间下CFG-WPI Maillard共聚物对乳液稳定性的影响;并进一步采用不同乳化剂制备包载姜黄素的乳液体系,并探究其消化特性。结果表明,CFG-WPI Maillard共聚物最佳制备条件为加热温度60 ℃、相对湿度79%、反应时间96 h。与单一CFG、WPI以及CFG-WPI混合物相比,CFG-WPI Maillard共聚物制备的姜黄素乳液粒径以及澄清指数较小,且对pH值、Ca2＋浓度等外界环境因子表现出较强的抵抗力,说明CFG-WPI Maillard共聚物制备的乳液稳定性最高。姜黄素乳液消化特性结果表明,CFG的加入有助于减缓脂质水解速率,与单一WPI相比,CFG以及CFG-WPI混合物制备的乳液中姜黄素的生物有效性较高。而对于共聚物构建的乳液体系而言,粒径是影响姜黄素乳液消化特性以及生物有效性的一个重要因素。本研究为了解CFG-WPI Maillard共聚物乳液的形成规律及消化特性提供了一定的参考,同时为CFG的增值利用提供了新途径。     

Molecular characteristics of partially hydrolyzed fucoidans from sporophyll of Undaria Pinnatifida and their in vitro anticancer activity

The effects of molecular characteristics on the anticancer activity of fucoidans were investigated after hydrolysis by copper acetate and then fractionation with 30 and 5 kDa membranes, which produced three fucoidan fractions: F_>30 K, F_5–30 K and F_<5 K. The F_>30 K and F_5–30 K consisted of mostly carbohydrate (58.2–61.3%) and sulphate (31.7–35.5%) with small amounts of proteins (1.2–6.4%). However, the major constituents of F_<5 K were sulphate (31.8%) and ash (37.5%) with smaller amounts of carbohydrate (15.5%) and protein (1.2%). The molecular weights (M_w) of F_>30 K, F_5–30 K and F_<5 K, obtained by a light scattering technique, were 262, 5.6 and 1.6 kDa, respectively. The observed anticancer activities were 18.0–28.5% for F_>30 K, 19.2–57.5% for F_5–30 K and 26.5–36.5% for F_<5 K, respectively, in the concentration range of 0.2–0.8 mg/mL. The results suggest that the anticancer activity of fucoidans could be considerably improved by lowering their M_w and by improving the binding properties of sulphate groups possibly through changing the molecular conformation.     

Isolation and characterization of galactomannan from Dimorphandra gardneriana Tul. seeds as a potential guar gum substitute

A galactomannan was obtained from mature seeds of Dimorphandra gardneriana Tul., the plant from which rutin is extracted. The galactomannan extraction was based on manual separation of the endosperm, water dissolution, centrifugation and precipitation with ethanol. The galactomannan yield obtained (31%) was similar to values reported for other Brazilian seeds and to that of guar gum. The polysaccharide from D. gardneriana seeds (GalDG) was characterized by gas–liquid chromatography (GLC), gel permeation chromatography (GPC), rheology and also by ¹³C and ¹H nuclear magnetic resonance (NMR). The monosaccharide composition in weight % was mannose 64.2, galactose 34.7 and glucose 1.1. Small amounts of protein and uronic acid were found, values being 1.75 and 2.8% (w/w), respectively. The mannose/galactose ratio of GalDG (1.84) is similar to values reported for galactomannans extracted from other Brazilian seeds, and is the M/G value closest to that of guar gum (1.6–1.8). The intrinsic viscosity of galactomannan from D. gardneriana (8.7 dL/g), in water at 25 °C, is lower than the [η] value of guar gum, but the absolute viscosity of the GalDG in aqueous solution at concentrations of 0.1 and 1% (w/v) is higher. The aqueous solution at 1% (w/v) behaves as a pseudoplastic fluid, but a Newtonian behavior was noted for the solution at 0.1%. The high average molar masses, M_w of 3.9 × 10⁷ g/mol and M_n of 1.9 × 10⁷ g/mol, determined by GPC are probably due to molecular aggregation. ¹³C and ¹H NMR spectra (DEPT 135 and HSQC) of GalDG solutions in D₂O were recorded. The patterns of mannose substitution in GalDG and guar gum are similar.     

Antioxidant activities of different fractions of polysaccharide conjugates from green tea (Camellia Sinensis)

Three fractions of water-soluble polysaccharide conjugates, coded as TPC-1, TPC-2, and TPC-3, were isolated and purified from low-grade green tea (Camellia sinensis) by absorbent chromatography and ion exchange chromatography. Their chemical and physical characteristics were determined by chemical methods, gas chromatography and size exclusion chromatography with laser light scattering. Deoxyribose assay, photoreduction of Nitro Blue Tetrazolium (NBT) assay and lipid peroxidation inhibition assay were applied to test the antioxidant activities of tea polysaccharide conjugates in vitro. The results indicated that the three polysaccharide conjugates were heteropolysaccharides bounded with protein. TPC-1 was composed of l-arabinose (Ara), d-ribose (Rib), d-xylose (Xyl), d-glucose (Glc), d-galactose (Gal) and d-mannose (Man). TPC-2 was only composed of four monosaccharides: Ara, Rib, Glc and Man. There was no Man detected in TPC-3. The protein contents of TPC-1, TPC-2, and TPC-3 were 2.8%, 3.8% and 4.0% and the molecular weights were 26.8 × 10⁴, 11.8 × 10⁴, 4.2 × 10⁴, respectively. TPC-3 showed the highest antioxidant activities among the three fractions of polysaccharide conjugates, with an IC₅₀ of 182 μg/ml for the deoxyribose assay, and 93 μg/ml for the photoreduction of NBT assay, values which were lower than those of TPC-1 and TPC-2 (P < 0.01). The effects of the molecular weight and protein content of the polysaccharide conjugates on the improvement of the bioactivities appeared to be significant.     

Identification of angiotensin I-converting enzyme inhibitory peptides from koumiss, a traditional fermented mare's milk

Angiotensin I-converting enzyme (ACE) inhibitory activities in untreated koumiss and koumiss digested with ACE, pepsin, trypsinase, and chymotrypsin were compared and analyzed. Four novel ACE inhibitory peptides (P_I, P_K, P_M, and P_P) were purified using ultrafiltration and high performance liquid chromatography (HPLC). The classification study showed that these 4 peptides were of the true inhibitor type. The amino acid sequences of these peptides are YQDPRLGPTGELDPATQPIVAVHNPVIV, PKDLREN, LLLAHLL, and NHRNRMMDHVH, respectively. Their individual IC₅₀ (50% inhibitory concentration) values were as follows: 14.53 ± 0.21 μM, 9.82 ± 0.37 μM, 5.19 ± 0.18 μM, and 13.42 ± 0.17 μM. From sequence analysis, we determined that P_I was part of β-casein in mare's milk. The 3 peptides P_K, P_M, and P_P did not correspond with any known milk protein. The results suggest that koumiss is rich in ACE inhibitory peptides, and the ACE inhibitors in koumiss are of the pro-drug type or a mixture of the pro-drug type and the true inhibitor type. These results may provide evidence about the beneficial effects of koumiss, especially on cardiovascular health.     

Short communication: Effect of increasing levels of corn bran on milk yield and composition

Thirty-nine lactating Holstein cows (23 multiparous and 16 primiparous) were randomly assigned to 1 of 3 dietary treatments in a crossover design. Dietary treatments differed by the proportion of corn bran [10, 17.5, and 25% dry matter (DM); designated as low, medium, and high] replacing corn silage and alfalfa. The corn bran coproduct contained 8.2% moisture and 12.9% crude protein, 30.4% neutral detergent fiber (NDF), and 45.0% nonfiber carbohydrate, 9.9% ether extract, and 0.70% P (DM basis). The low treatment consisted of 15.8% NDF from forage (fNDF) and 33.1% total NDF; the medium treatment consisted of 12.9% fNDF and 32.5% total NDF; and the high diet contained 9.9% fNDF and 31.8% total NDF. Dry matter intake was not affected by treatment. The percent milk fat decreased by 0.26% with the inclusion of corn bran from 10 to 25% of the diet DM, but total milk fat yield was not affected. In comparison, corn bran increased yield of milk protein 0.12 kg/d when bran increased from 10 to 25% of the diet DM. Total milk yield tended to increase when bran increased from 10 to 25% of the diet DM, but no differences were observed on 3.5% fat-corrected milk. Lastly, feed conversion significantly improved with increasing inclusion: 1.39, 1.39, and 1.55 ± 0.05 kg of milk/kg of DMI for low, medium, and high, respectively. Observed effects were likely due to the increase in energy intake associated with increasing levels of corn bran.     

Effects of replacing pork back fat with vegetable oils and rice bran fiber on the quality of reduced-fat frankfurters

The effects of substituting olive, grape seed, corn, canola, or soybean oil and rice bran fiber on the chemical composition, cooking characteristics, fatty acid composition, and sensory properties of low-fat frankfurters were investigated. Ten percent of the total fat content of frankfurters with a total fat content of 30% (control) was partially replaced by one of the vegetable oils to reduce the pork fat content by 10%. The moisture and ash content of low-fat frankfurters with vegetable oil and rice bran fiber were all higher than the control (P < 0.05). Low-fat frankfurters had reduced-fat content, energy values, cholesterol and trans-fat levels, and increased pH, cooking yield and TBA values compared to the controls (P < 0.05). Low-fat frankfurters with reduced-fat content plus rice bran fiber had sensory properties similar to control frankfurters containing pork fat.     

Decrease of available lysine in thermally treated gelatin followed by LC–UV: Influence on molar mass and ability to helixes’ formation

Available lysine (AL) content, weight-average molar mass (M_w) and kinetic of α helixes’ formation have been determined in thermally treated gelatin (75 °C) during 2, 6 and 8 days. Quantification of available lysine in gelatin sample by LC–UV has been developed. Thermal treatment during 8 days led to a decrease of AL content from 3.1 g/100 g of gelatin to 2.3 g/100 g of gelatin. In the same time, M_w increased from 6.7 × 10⁵ g mol⁻¹ to more than 2.0 × 10⁶ g mol⁻¹ and α helixes’ formation ability was strongly affected. Thermal treatment led to the reaction of available lysine group with other functions present in its environment. Intermolecular cross-links led to a high molar mass compounds’ formation and limited protein chain unfolding which is an essential step for helixes’ formation.     

Short communication: Little change takes place in Camembert-type cheese water activities throughout ripening in terms of relative humidity and salt

Water activity (a_w) affects the growth and activity of ripening microorganisms. Moreover, it is generally accepted that a_w depends on relative humidity (RH) and salt content; these 3 variables were usually measured on a given day in a cheese without the microorganism layer and without accounting for a distinction between the rind, the underrind, and the core. However, a_w dynamics have never been thoroughly studied throughout cheese ripening. Experimental Camembert cheeses were ripened under controlled and aseptic conditions (temperature, gaseous atmosphere, and RH) for 14 d. In this study, only RH was varied. Samples were taken from the cheese (microorganism layer)–air interface, the rind, and the core. The a_w of the cheese–air interface did not change over ripening when RH varied between 91 and 92% or between 97 and 98%. However, on d 5, we observed a small but significant increase in a_w, which coincided with the beginning of growth of Penicillium camemberti mycelia. After d 3, no significant differences were found between the a_w of the cheese–air interface, the rind, and the core. From d 0 to 3, cheese rind a_w increased from 0.94 to 0.97, which was probably due to the diffusion of salt from the rind to the core: NaCl content in the rind decreased from 3.7 to 1.6% and NaCl content in the core increased from 0.0 to 1.6%. Nevertheless, a_w did not significantly vary in the core, raising questions about the real effect of salt on a_w.     

Antihypertensive effect of corn peptides,produced by a continuous production in enzymatic membrane reactor,in spontaneously hypertensive rats

The aim of this study was to produce corn peptides (CP) with potent angiotensin converting enzyme (ACE)-inhibitory activity and to investigate antihypertensive effects in spontaneously hypertensive rats (SHRs). Results showed that the hydrolysate yield and quality were stable during continuous CP production using an enzymatic membrane reactor (EMR). The hydrolysate was then filtered through a 3 kDa cut-off membrane and the IC₅₀ value of permeate was decreased fourfold (IC₅₀ = 0.29 mg protein/ml). Gastric-intubation CP (M_w < 3 kDa) at a dose of 100 mg/kg bw revealed the best antihypertensive effects in both acute and long-term animal studies using SHRs’ models, the reductions in maximal systolic blood pressure (SBP) were 26.57 mm Hg and 34.45 mm Hg, respectively. Long-term antihypertensive effect of CP administration at a dose of 100 mg/kg bw was comparable to Captopril at 2 mg/kg bw dose. The CP significantly inhibited the ACE activities in SHRs’ lungs and testes (p < 0.01 ∼ p < 0.05) suggesting that these were CP’s target sites.