Antioxidant activity of barley as affected by extrusion cooking

Grit from different hulled barley cultivars was subjected to extrusion cooking and the effect of extrusion moisture and temperature on the antioxidant properties was studied. A significant decrease in the total phenolic content (TPC) and total flavonoid content (TFC) was observed upon extrusion and a further decrease of 8-29% in TPC and 13-27% in TFC was observed when both the feed moisture and extrusion temperature were increased. The antioxidant activity (AOA) increased significantly upon extrusion and this increase was the highest (36-69%) at 150 °C and 20% feed moisture. The increase in feed moisture and temperature significantly increased the metal chelating activity. The reducing power decreased significantly upon extrusion as compared to their corresponding control samples. Extrusion lead to a greater increase in non-enzymatic browning (NEB) index however, increasing the moisture content of feed decreased the NEB index by 3-29% (at 180 °C) and 1-17% (150 °C), while increasing the temperature increased the NEB significantly.     

Dietary fiber profile of barley flour as affected by extrusion cooking

Barley grains, Phoenix and CDC-Candle, were extruded in a twin-screw extruder at 90−140 °C and 20–50% moisture level. Effects of extrusion conditions on total (TDF), soluble (SDF), and insoluble dietary fiber (IDF) were determined. The content of SDF and TDF increased upon extrusion cooking of both types of barley flours. The changes in IDF content were found to be variety-dependent. Only a minor decrease in IDF content of CDC-Candle barley was found, but an increase in IDF content of Phoenix was observed at all extrusion temperatures. The increase in SDF, in both barleys, could be due to the transformation of some IDF into SDF during extrusion and the formation of additional SDF by transglycosidation. The increase in IDF in Phoenix flour could be due to the formation of retrograded amylose [resistant starch (RS3)] during extrusion cooking and subsequent cooling.     

Effects of oat lipids on groat meal pasting properties

The Australian oat cultivar Yarran is unacceptable for human food use due to poor flavour, colour and texture. It has a high lipid content which contains a high proportion of oleic acid. It was compared with an acceptable variety, Mortlock, which has a characteristically lower lipid content with a lower proportion of oleic acid, to study the effect of lipid content on pasting properties of the oat meal. The lipids of both varieties were extracted with petroleum ether and were added back into the defatted meals in sequential amounts. These meals were then tested for viscosity parameters. Both lipid content and composition significantly influenced the meal pasting properties. The peak viscosity and time to peak viscosity were negatively correlated with lipid content whereas setback and pasting temperature increased with increased lipid content. The lipids from Yarran and Mortlock had different effects on the pasting properties. The Mortlock lipid increased the final viscosity (FV) of the defatted meal of Yarran but showed little effect on the FV of its own cultivar. However, the results indicated that the lipid content/composition, although affecting pasting characteristics substantially, were not as important as other meal properties in controlling acceptability for human food use. © 1999 Society of Chemical Industry     

Changes of phosphorus and trace elements species in rye and oat flakes and oat porridge induced by simulated digestion

Fractionation of chemical species of phosphorus, manganese, iron, nickel, copper, zinc and molybdenum in rye and oat flakes and porridge made of oat flakes was studied by size exclusion chromatography coupled to inductively coupled plasma mass spectrometry. The effect of in vitro simulated digestion of the samples was elucidated by comparison of the digestates and the extracts of the samples (in the Tris–HCl buffer solution, pH = 7.5). The procedure of simulated digestion included two steps: the pepsin-catalysed hydrolysis in diluted hydrochloric acid (pH = 1.7) followed by the pancreatin-catalysed hydrolysis at pH = 7.5. The enzyme-catalysed digestion of the samples results in alteration of iron, copper and zinc species distribution. The species of phosphorus in original cereal samples are distributed between two fractions: a medium-molecular mass fraction (15 kDa) and a low-molecular mass fraction (2 kDa). This pattern is also kept basically in the sample digestates. In digested samples, the majority of soluble iron is bound in a medium-molecular mass fraction (20 kDa), while in the extracts only traces of iron were found in a high-molecular mass fraction. Approximately 90% of the soluble zinc in the digestates of cereal flakes is represented by non-bound zinc ions. The bound zinc is mostly concentrated in a low-molecular mass fraction (1–2 kDa) together with some copper and almost all nickel. The low-molecular mass fractions (1–2 kDa) of nickel, copper and zinc present in extracts of original samples correspond quite well to those in the respective digestates. Molybdenum species occurs in another low-molecular mass fraction.     

Changes in milk protein fraction as affected by subclinical mastitis

From cows that had both healthy quarters and quarters with subclinical mastitis [somatic cell count (SCC) 84,000 vs. 293,000/ml in bucket milk], foremilk, bucket milk, and stripping and residual milks were collected. Young milk was obtained 1.5 h later following a repeated oxytocin injection. Compared with milk from healthy quarters, milk from quarters with subclinical mastitis showed elevated SCC, plasminogen, and protein and had increased activity of n-Acetyl-beta-D-glucosaminidase (NAGase) and plasmin, as well as elevated portions of whey proteins and gamma-casein in the total protein. The SCC and the other mentioned parameters were also higher in the foremilk and the stripping and residual milks compared with bucket milk, independent of the udder health status; however, decreased values were found for total protein. Young milk showed an increase of SCC and n-Acetyl-beta-D-glucosaminidase activity compared with bucket milk. Because of lower levels of total plasmin and gamma-casein, we concluded that this young milk was newly synthesized milk containing some casein degradation products and that proteolysis of casein continued in the udder until the next milking. The n-Acetyl-beta-D-glucosaminidase activity was shown to be a better indicator for subclinical mastitis and correlated better with protein degradation than did SCC.     

燕麦发芽过程中营养成分变化

为了探究燕麦发芽过程中主营养成分的变化,对燕麦在20℃发芽8 d过程中主要营养成分的变化进行测定。结果表明:燕麦发芽过程中,游离氨基酸、还原糖、磷脂在发芽4 d时含量最高,分别为250 mg/100g、5.3 mg/g、10.2 g/100g;蛋白质、生物碱在发芽6 d时最多,为20.5%、54.6 mg/100g;总酚发芽7 d时最高,为1.73 mg/g;维生素C在8 d时含量高达31.2 mg/g。燕麦发芽后主要营养物质在4~6 d营养价值最高,为最佳使用时间。     

Changes in milk composition as affected by subclinical mastitis in sheep

The mechanism of the effects of glandular-level subclinical mastitis in dairy sheep on milk yield and on its composition as expressed in curd yield was studied. Thirty-six Israeli-Assaf dairy sheep with one udder half infected with identified coagulase-negative staphylococci and the contralateral gland free of bacteria were chosen. The milk yield of the infected halves was significantly lower than that of the uninfected ones (0.36 vs. 0.76 kg/milking). The somatic cell count and N-acetyl-beta-D-glucosaminidase activity were significantly higher in the infected halves than in the uninfected ones. The plasminogen activator and plasmin (PL) activities were significantly higher in the infected glands than in the uninfected ones, whereas plasminogen (PLG) activity and the ratio PLG:PL were significantly lower in the infected glands. Concentrations of Ca2+ did not differ, whereas Ca2+ activity was significantly lower and proteose peptone concentration was 2.4 times as high in the infected glands than in the uninfected ones. Curd yield was significantly lower in the infected glands than in the uninfected ones.     

Changes in milk composition as affected by subclinical mastitis in goats

The mechanism of the effects of subclinical mastitis (SM) at the glandular level in dairy goats on milk yield and its composition as expressed in curd yield (Yc) was studied. Twenty-five Israeli goats of various crossbreeds were chosen; one udder half was naturally infected with identified coagulase-negative staphylococci, and the contralateral gland was free of bacteria. The milk yield of the infected halves was significantly lower than that of the uninfected ones. Somatic cell count and N-acetyl-beta-D-glucosaminidase activity were significantly higher in the infected halves. The lactose concentration in the infected glands was significantly lower than that in the uninfected ones, casein concentrations did not differ, and the whey protein and albumin concentrations were significantly higher in the infected glands. Plasmin activity was significantly higher in the infected glands, whereas plasminogen activity was undetectable. Concentrations of Ca2+ did not differ, whereas Ca2+ activity was significantly lower in the infected glands. The proteose peptone concentration was 1.5 times as great in the infected glands as in the uninfected ones. The Yc was significantly lower in the infected halves, and clotting time was significantly longer. The mechanisms of the effects of SM on milk yield and Yc in goats and sheep are discussed and compared.     

Changes in leaf protein lipids in vitro

The lipids were responsible for the development of rancidity in leaf protein concentrates from wheat, kale, maize and red clover on prolonged exposure to air. Phospholipids were shown to oxidise more rapidly than neutral fats. The enzyme systems causing changes in the leaf protein concentrate were inactivated by heating the protein in nitrogen at 100°, but non-enzymic oxidation of the lipids continued. Addition of ascorbic acid failed to prevent oxidation, but dried ‘amla’ (Emblica officinalis) fruit reduced oxidation considerably. Dried ‘amla’ leaf powder was more effective and ‘jantar’ (Sesbania aegyptica) leaf powder was less effective.     

Changes in quality characteristics of fresh-cut jujubes as affected by pressurized nitrogen treatment

When fresh-cut jujubes are subjected to pressurized nitrogen treatments, the nitrogen gas dissolves into water and forms clathrate hydrates which ultimately lead to restriction in water mobility. Fresh-cut jujubes were, respectively, treated with 1.0 MPa nitrogen, 1.5 MPa nitrogen, 1.9 MPa nitrogen and 1.9 MPa air for 30 min at 4 °C and without pressurized treatment(control) and then stored at 4 °C and 80 % relative humidity (RH) for 12 days. Physiological, textural, chemical, and microbial attribute were determined every 2 days. Results indicated that pressurized nitrogen treatments carried out at 1.5 MPa successfully inhibited respiration, water loss, softening, chlorophyll degradation, and color change. The treatments also significantly reduced loss of ascorbic acid and soluble solids. Treated fresh-cut jujubes carried significantly less microbial population. Thus, it was concluded that pressurized nitrogen treatment was beneficial to preserve quality of fresh-cut jujubes.     

Changes in volatile flavour compounds in field pea cultivars as affected by storage conditions

The impact of storage conditions on volatile flavour profile of field pea cultivars was evaluated. Seeds were kept at 4 °C, room temperature (approximately 22 °C) and 37 °C for 12 months. Headspace solid‐phase microextraction gas chromatography–mass spectrometry was used for extraction and identification of volatile flavour compounds (VFCs). Significant (P < 0.01) differences in the concentration of VFCs were observed during storage. All cultivars kept at 22 and 37 °C had higher mean value of aldehydes compared to those kept at 4 °C. Alcohols, hydrocarbons, ketones, terpenes and esters were higher in samples stored at 4 °C compared to those at higher temperatures. 1‐Hexanol, hexanal, styrene, 2‐butanone, dimethyl sulphide, 3‐carene, ethyl acetate and 2, 3‐diethyl‐5‐methyl pyrazine were the most abundant compounds found in peas. Results from this study could be useful in identifying improved conditions of storage to enhance flavour properties of peas.     

莜麦中蛋白与多糖成分对四氧嘧啶致糖尿病小鼠血糖、血脂影响的比较

目的:比较莜麦中蛋白和多糖成分对四氧嘧啶致糖尿病小鼠血糖、血脂的影响。方法:通过注射四氧嘧啶建立糖尿病小鼠模型,用相同剂量的莜麦蛋白和多糖分别灌胃糖尿病模型小鼠和正常小鼠,并设正常对照组及模型对照组,观察小鼠的体重及血糖值的变化情况。10d后,眼眶采血测定血糖(GLU)、总胆固醇(CHOL)、三酰甘油(TG)及高密度脂蛋白(HDL)水平。结果:莜麦蛋白和莜麦多糖都具一定的降血糖功效,且莜麦多糖的降糖功效优于莜麦蛋白;莜麦蛋白和多糖均能维持血清中三酰甘油处在相对较低的水平,且莜麦蛋白较莜麦多糖更能改善总胆固醇及高密度脂蛋白的相对含量,使其趋于正常值。结论:莜麦多糖控制糖尿病小鼠血糖值的作用较莜麦蛋白更快,更明显,而莜麦蛋白改善血清中总胆固醇及高密度脂蛋白的功效更突出。     

Changes in the apparent viscosity profiles of casein suspensions as affected by plant enzymes

The aim of this work was to study the degree of hydrolysis and changes in the apparent viscosity of casein suspensions as a result of various enzymes addition. Suspensions with 3, 12 and 15 g/100 mL of casein, at pH 5.2, 6.0 and 6.5 were prepared in buffer solutions. Previous standardization; plant (papain and bromelain) and animal (chymosin) enzymes were added to hydrolize the casein suspensions. A control with no enzyme addition was used. The rheological behaviour was determined using a rotational rheometer (Haake RV20), with a cone and plate geometry. The Casson and the power law equations were applied to the data. The degree of hydrolysis was a function of the enzyme, pH and casein concentration, presenting chymosin the highest values. All enzymes showed the highest activity at acidic pH. Also, some substrate inhibition was observed. All samples behaved as non-Newtonian, shear-thinning systems with a yield stress value. In all cases, a significant increase in the viscosity was observed when shifting from 3 to 12 g/100 mL. Further increase in concentration caused an opposite effect. Changes in pH of the casein suspensions affected the viscosity, presenting maximum values at pH 6.0. The Casson equation fitted the results better than the power law model.     

Changes in the body immunological status of peptic ulcer patients as affected by dietotherapy

The findings are presented characterizing the immunologic status of peptic ulcer patients during dietetic treatment. The immunologic shifts detected on admission to hospital (increased reactivity of T cells to specific antigen, immunoglobulin imbalance, changed concentrations of some complement components in the blood serum) were found to normalize under the effect of diets. The authors consider that dietetic treatment should be an obligatory component of the comprehensive management of peptic ulcer patients.     

挤压预处理后小麦面筋蛋白酶解特性的变化

小麦面筋蛋白经挤压预处理后,利用复合蛋白酶(Protamex)和木瓜蛋白酶(Papain)酶解。与未挤压的酶解产物相比较,经挤压预处理后的酶解产物水解度明显提高(77%～122%),鲜味明显增强,但蛋白质回收率有所下降。挤压预处理后的小麦面筋蛋白酶解产物高分子组分减少,低分子组分显著增加,面筋蛋白酶解液中的鲜味物质以小分子肽和游离氨基酸为主。     

Changes in the non-structural carbohydrates associated with the field drying of oat forage

Two trials were conducted to determine the sugars, fructans and starch in oat plants (Avena sativa L) and the changes occurring in these carbohydrate fractions during field drying in the haymaking process. The composition of oat herbage in non-structural carbohydrates varied markedly between years; the contents of sugars, fractals and starch in both leaf blade and non-leaf blade materials being nether in 1990–1991 than in 1991–1992. Field drying produced a significant decrease (P < 0.05) in the amount of soluble carbohydrates. For the whole aerial plant parts, the decline in the fructans concentration ranged between 42.8 and 38.2% and that of sugars between 16.5 and 5.8%. The total losses of sugars and fractions in hay, expressed as losses of dry matter, ranged from 88 to 63 g kg^?1 depending on the year.