Emulsifying activity and emulsion stability of corn gluten meal

Corn gluten meal with good emulsifying activity and emulsion stability may have potential in food uses. Commercial corn gluten meal from various producers had a pH around 4 and showed no emulsifying activity. Reducing the particle size to below 15 µm or increasing the pH to 6.6 (with particle size above 53 µm) did not improve the emulsifying activity. When the particle size was reduced to below 44 µm and the pH was adjusted to 6.6 or above, good emulsifying activity and good emulsion stability could be obtained. The emulsifying activities of corn gluten meals (<44 µm) from four different producers at around pH 8 ranged from 49.3 to 51.5 and the corresponding emulsion stabilities ranged from 39.7 to 49.5. There was no significant variation in emulsifying activity between pH 6.9 and 7.8 when NaOH, LiOH and KOH were used to adjust the pH, but LiOH‐ and KOH‐adjusted meal at around pH 7.8 showed better emulsion stability than NaOH‐adjusted meal. Good emulsifying activity of corn gluten meal could be obtained in NaCl solutions at sufficiently high pH. Published in 2001 for SCI by John Wiley & Sons, Ltd.     

玉米多肽制备方法及其功能活性研究进展

玉米蛋白粉是玉米湿磨生产淀粉中的主要副产品,其低水溶性、必需氨基酸缺陷等因素限制了其在食品工业中的应用。水解玉米蛋白粉制备玉米多肽是其高附加值利用方式之一,可以极大提高玉米蛋白粉的功能性和生物活性。本文重点介绍了玉米多肽的主要制备方法以及玉米多肽在抗氧化、抗血糖、抗高血压、醒酒护肝等方面的生物学功能,归纳总结了现有研究存在的问题及未来的发展前景,对食品企业高效利用玉米蛋白粉开发生物活性肽、提升行业经济效益具有重要意义。     

玉米蛋白加工利用研究进展

在湿法玉米淀粉加工中,玉米蛋白存在于副产物玉米黄粉、玉米胚芽饼和玉米浆中。文章在分析玉米蛋白氨基酸组成等特性的基础上,综合分析玉米蛋白加工利用现状和玉米蛋白水解物的功能特性,指出玉米蛋白水解物在食品工业上应用的潜力。     

响应面法优化玉米蛋白挤出工艺

双螺杆挤出改性处理脱脂玉米蛋白粉。以脱脂玉米蛋白粉含水量、挤出温度、螺杆转速为响应因素,可溶性蛋白含量为响应值,采用响应面分析方法,确定脱脂玉米蛋白粉挤出改性的最佳工艺条件。结果表明：物料含水量68%、挤出温度163℃、螺杆转速30Hz(225r/min)时,挤出脱脂玉米蛋白粉中可溶性蛋白含量最高,为3.43%。采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)测定挤出改性后玉米可溶性蛋白的分子质量分布,结果显示其分子质量介于3500～14300D之间,且主要是分子质量为3500～6500D的多肽。改性后的玉米蛋白粉其理化性质都有了较明显的改善,说明双螺杆挤出改性玉米蛋白粉效果明显,切实可行。     

提取条件对玉米黄粉中淀粉含量影响的研究

采用分光光度法测定玉米黄粉中的淀粉含量,研究了α-淀粉酶用量、pH、水浴时间、水浴温度等提取条件对玉米黄粉中淀粉含量的影响。通过正交实验优化了玉米黄粉中淀粉测定最佳工艺条件为pH7.5、α-淀粉酶用量为20mg/g、水浴温度50℃、水浴时间50min。     

营养玉米饺子粉配粉工艺及品质特性研究

研究以玉米粉-膨化玉米粉为主,添加活性谷朊粉和大豆蛋白制备营养玉米饺子粉的工艺。通过单因素和正交试验,获取最佳配比为玉米原粉：玉米膨化粉：活性谷朊粉：大豆蛋白为51：34：10：5。在此条件下营养玉米饺子粉的感官评分最佳,蒸煮损失率为6．45％,延伸性为10．612mm,回复性为0．287。     

超声波法提取玉米醇溶蛋白的研究

玉米醇溶蛋白 (zein)具有良好的成膜特性 ,应用在食品、化工、医药和生物降解包装材料方面有着诱人的前景。本研究应用超声波技术从玉米蛋白粉 (CGM )中提取zein并脱色。脱色条件是 :无水乙醇、液料比为 6∶1(mL∶g)、超声时间为 5 0min ;zein最佳提取工艺为 :pH值 12、液料比 6∶1(mL∶g)、体积分数 80 %乙醇、超声时间为 3 0min ,提取率达到 2 7%以上 ,产品纯度为 88 3 % ,颜色淡黄。     

Response of lactating dairy cows to diets containing wet corn gluten feed or a raw soybean hull-corn steep liquor pellet

We evaluated effects of wet corn gluten feed (WCGF) and a novel product (SHSL) containing raw soybean hulls and corn steep liquor on performance and digestion in lactating dairy cows. In Experiment 1, 46 multiparous Holstein cows were assigned to control (C), WCGF (20% of diet DM), or SHSL (20% of diet DM). Diets were fed as a total mixed ration beginning after calving. The C diet contained (dry matter [DM] basis) 30% alfalfa hay, 15% corn silage, 32% corn, 9.3% whole cottonseed, 4.4% solvent soybean meal (SBM), and 3.3% expeller SBM. The WCGF replaced 10% alfalfa hay, 5% corn silage, and 5% corn grain, while expeller SBM replaced solvent SBM to maintain diet rumen undegradable protein. The SHSL replaced 10% alfalfa hay, 5% corn silage, 3% solvent SBM, and 2% corn. Dietary crude protein averaged 18.4%. Milk, energy-corrected milk (ECM), DM intake (DMI), and ECM/DMI were similar among diets during the first 13 wk of lactation. During wk 14 through 30 postpartum, WCGF and SHSL improved milk, ECM, milk component yield, and ECM/DMI. In Experiment 2, 6 cows were used to evaluate digestibility and rumen traits. Dry matter intake and total tract digestibilities of DM, fiber, and crude protein were not different among diets. Diets did not affect ruminal liquid dilution rate, pH, or concentrations of total volatile fatty acids or ammonia, but acetate:propionate was higher for C (3.38) than for WCGF (2.79) or SHSL (2.89). The WCGF and SHSL products can serve as alternative feedstuffs in diets fed to lactating dairy cattle.     

中性蛋白酶水解玉米蛋白粉制备可溶性肽最佳条件的研究

通过对酶法水解玉米粉蛋白制备多肽的工艺进行了研究,实验以水解度(DH)和氮溶解指数(NSI)为指标确定了最佳酶解工艺条件。结果表明,在pH7.5、酶解温度50℃、酶与底物比2%、底物浓度5%的条件下酶解4h,可使水解度和氮溶解指数分别达到22.74%和23.86%。     

Responses of dairy cows to supplemental rumen-protected forms of methionine and lysine.

Multiparous Holstein cows at six universities were utilized to examine effects of ruminally protected methionine and lysine on lactational performance. Three hundred and four cows began the study; 259 cows were included in the production analysis. Following a 21-d standardization period, cows received a basal diet of corn silage and ground corn supplemented with one of five dietary treatments, which were supplements of soybean meal or corn gluten meal, the latter with zero and three combinations of protected methionine and lysine (methionine; methionine and lysine; methionine and double (2x) lysine). Treatment effects were evaluated during early, mid, late, and total lactation (22 to 112, 113 to 224, 225 to 280, and 22 to 280 d postpartum, respectively). On a DM basis, ratios of forage to concentrate (50:50, 60:40, and 70:30) increased, and dietary CP (16.0, 14.5, and 13.0%) decreased during the three periods of lactation. Amount of amino acid supplementation also decreased (15, 12, and 9 g/d methionine; 20, 16, and 12 g/d lysine; and 40, 32, and 24 g/d 2x lysine) with period of lactation. Actual and least squares means for milk, FCM, and milk protein yields were greater for soybean than for corn gluten meal during early, mid, and total lactation. In addition, these variables responded linearly to lysine in early lactation. Response to lysine was quadratic during mid and total lactation for these variables. Differences in nutrient intake explained production responses to protein sources but not to lysine. Serum amino acid responses primarily reflected differences in dietary protein source and rumen-protected amino acid.     

Growth and nutrient digestion by dairy heifers fed semipurified diets

Holstein heifers, which weighed an average of 154 kg, were randomly assigned to three dietary treatments in a split plot in time design. Differences in diets were fiber source: solka floc, corn cobs, and corn silage. The major source of added protein was corn gluten meal. Total collection metabolism periods were the final 7 d of each of two 30-d periods. Several heifers had simple digestive disturbances, which appeared to be related to low ruminal pH, while consuming the solka floc diet. Average daily gains were .78, .83, and 1.02 kg/d for treatments solka floc, corn cobs, and corn silage, respectively. Gains were within the range of acceptable growth standards and were higher than reports in the literature for semipurified and purified diets. Protein in corn gluten meal appeared to be utilized efficiently by the heifers for growth. The solka floc and corn cob diets are acceptable for growing dairy heifers where a low mineral content is desired but normal growth rates need to be maintained. The solka floc diet might be improved by including a buffer to help stabilize rumen pH.     

Evaluation of DNA extraction methods for Bacillus anthracis spores spiked to food and feed matrices at biosafety level 3 conditions

The DNA extraction efficiency from milk, whey, soy, corn gluten meal, wheat powders and heat-treated corn grain that were spiked with Bacillus anthracis and Bacillus thuringiensis spores was determined. Two steps were critical: lysis of the spores and binding of the free DNA to the DNA binding magnetic beads in the presence of the interfering powders. For the guanidine-thiocyanate based Nuclisens lysis buffer from Biomerieux we found that between 15 and 30% of the spores survived the lysis step. As most lysis buffers in DNA/RNA extraction kits are guanidine based it is likely that other lysis buffers will show a similar partial lysis of the Bacillus spores. Our results show that soybean flour and wheat flour inhibited the DNA extraction process strongest, leading to unreliable DNA extractions when using too much of the matrix. For corn gluten meal, heat-treated corn grain and milk powders, DNA extraction efficiencies in the presence of 100mg and 10mg of powder resulted in 70%-95% reduced DNA recoveries. The inhibition was, however, reliable and intermediate compared to the inhibition by soy and wheat. Whey powder had the lowest inhibitory effect on DNA-extraction efficiency and recoveries of 70-100% could be reached when using 10mg of powder. The results show that reducing the amount of matrix leads to better DNA-extraction efficiencies, particularly for strongly inhibiting powders such as soy and wheat. Based on these results, a standard protocol to directly isolate DNA from micro-organisms present in complex matrixes such as food and feed powders was designed.     

居间驹形氏杆菌发酵大豆糖蜜生产细菌纤维素条件的优化

通过居间驹形氏杆菌(Komagataeibacter intermedius CGMCC12562)发酵生产细菌纤维素,以大豆糖蜜作主要发酵原料,优化发酵工艺参数,提高细菌纤维素产量。在单因素试验的基础上,筛选出对细菌纤维素产量影响较大的4个因素,即大豆糖蜜可溶性固形物含量、玉米蛋白粉、ZnSO_4及苹果酸添加量,并通过Design-Expert响应面分析对这4个因素进行优化,得到最优的培养基及发酵工艺为:大豆糖蜜可溶性固形物含量14.13°Brix、玉米蛋白粉添加量1.6%、ZnSO_4添加量0.11%、苹果酸添加量0.41%;在30℃、接种量10%、装料量16%、初始pH 6.0的条件下静置培养7d,细菌纤维素产量高达(15.68±0.82)g/L。     

玉米黄色素的提取工艺及应用研究现状

我国玉米产量大,玉米蛋白粉是玉米淀粉生产过程的下脚料,其中含有丰富的玉米黄色素,是玉米黄色素提取的理想原料。玉米黄色素可作为天然着色剂应用到食品工业。此外,因其有很强的抗氧化性,所以具有保护视力、抗癌、预防心血管疾病等生理功效。文章简述了玉米黄色素的组成和性质,并对其提取方法和应用现状进行了综述。     

Effect of rumen-protected lysine supplementation of diets based on corn protein fed to lactating dairy cows

This trial tested whether rumen-protected Lys (RPL) supplementation would improve the nutritive value of rumen-undegradable protein (RUP) from corn protein. Thirty-two lactating Holstein cows were blocked by days in milk and parity into 8 squares of 4 cows each in replicated 4 × 4 Latin squares. Treatments provided all supplemental crude protein from: (1) soy protein (67% expeller soybean meal plus 33% solvent soybean meal); (2) a blend of soy and corn protein (33% expeller soybean meal, 17% solvent soybean meal, 25% corn gluten meal plus 25% distillers dried grains with solubles); (3) corn protein (50% corn gluten meal plus 50% distillers dried grains with solubles); or (4) corn protein plus RPL [diet 3 top-dressed with RPL (125 g/d of AjiPro-L Generation 1, supplying an estimated 20 g of absorbable Lys/d)]. Diets contained (dry matter basis) 22% alfalfa silage, 43% corn silage, 18% ground high-moisture and dry corn, 2.4% mineral-vitamin premix, 1.5 to 3.9% soy hulls, 15% crude protein, 30 to 32% neutral detergent fiber and predicted to contain equal rumen-degradable protein, RUP, and metabolizable protein. Cows within squares were randomly assigned to treatment sequences and fed diets for 4-wk periods before switching; production data and blood samples were collected during last 2 wk of each period. Data were analyzed using the mixed procedures of SAS. Intake was highest on diet 1, intermediate on diets 2 and 3, and lowest on diet 4; body weight gain was highest on diet 3, intermediate on diets 1 and 2 and lowest on diet 4. Intakes and body weight changes were reflected by differences in milk/dry matter intake, which was highest on diets 2 and 4 and lowest on diet 3. Milk yield was lower on diet 3 (44.3 kg/d) than on diets 1, 2, and 4 (average 45.8 kg/d) and protein yield was highest on diets 1 and 2 (average 1.35 kg/d), intermediate on diet 4 (1.30 kg/d), and lowest on diet 3 (1.25 kg/d). No effects of diet were detected on ruminal metabolites. Free nonessential amino acids and total protein AA were elevated in blood plasma on diet 3, reflecting reduced utilization for milk protein synthesis. These results indicated that 50% dilution of soybean meal RUP with that from corn protein did not reduce yield and that supplementing RPL to the corn protein-based diet increased yield 1.1 kg of milk/d and 50 g of true protein/d.     

Dietary preference in dairy calves for feed ingredients high in energy and protein

In 3 experiments, we assessed preference of recently weaned dairy calves for (1) 8 high-energy feed types [barley meal, corn meal, corn gluten feed (CGF), oat meal, rice meal, sorghum meal, wheat meal, and wheat middlings meal]; (2) 6 high-protein feed types [corn gluten meal (CGM), wheat distillers dried grains, rapeseed meal, soybean meal (SBM), sunflower meal, and pea meal]; and (3) 4 mixtures (50:50) of the highest- and lowest-ranked high-energy and high-protein feeds, to assess whether calves maintain preference for feed ingredients that are included in a mixture. In all experiments, pairwise preference tests were conducted between all feed types (28 different pairwise preference tests in experiment 1, 15 tests in experiment 2, and 6 tests in experiment 3). Each pairwise preference test was conducted by offering ad libitum access to both feed types for 6 h. All tests were repeated with 20 Holstein calves. Before this study, calves were offered milk replacer at a rate of 4 L/d and a pelleted starter feed ad libitum. After weaning at 62 d of age, each calf was involved in a pairwise preference test at 3 and 5 d postweaning. A preference ratio was calculated for each calf in each test as (intake of feed type A)/(intake of feed type A + intake of feed type B). Preference for feed types was ranked across tests in each experiment using pairwise comparison charts. In experiment 1, the highest-ranked high-energy feed type was wheat meal and the lowest ranked were rice meal and CGF. In experiment 2, the highest-ranked high-protein feed type was SBM and the lowest ranked was CGM. According to the preference rankings from experiments 1 and 2, experiment 3 evaluated (50:50) mixtures of SBM + wheat meal, SBM + CGF, CGM + wheat meal, and CGM + CGF. The mixture of SBM + wheat meal was highest ranked, CGM + CGF was lowest ranked, and the mixtures containing one high-ranked and one low-ranked feed ingredient (SBM + CGF and CGM + wheat meal) were ranked equally. The results of this study indicate that young calves exhibit clear preferences for certain high-energy and high-protein feeds that may be considered highly palatable. Further, preference ranking of feed types provided as 50:50 mixtures was consistent with ranking of individual feed types, suggesting that palatability of mixed starter rations can be improved by inclusion of a preferred feed type.     

Extrusion Processing of Wet Corn Gluten Meal

Wet corn gluten meal (WCGM) is that which has not undergone the typical industrial flash drying process. The pH of WCGM was adjusted to 7.0. The samples were then frozen and the water removed by lyophilization. The moisture content of the freeze-dried samples was adjusted to 14, 20, and 26% dry basis and extruded at barrel temperatures of 120, 145, and 170°C with screw speeds of 100, 150, and 200 rpm. Changes in digestibility and water-holding capacity were measured, and the results were compared to similarly processed dry corn gluten meal (DCGM) at pH 7.0.     

镰刀菌毒素和改性蒙脱石吸附剂对全价饲粮发酵参数的影响

研究镰刀菌毒素和改性蒙脱石吸附剂(Calibrin-A,CA)对全价饲粮发酵pH、OM、NH_3-N和乳酸的影响。实验分为6个处理,对照组(Contr.)为基础饲粮,实验1组(25 Myco.)和实验2组(50 Myco.)分别用25%和50%的发霉玉米和发霉玉米蛋白粉代替基础饲粮中的玉米和玉米蛋白粉,实验3组(Contr.+CA)、实验4组(25 Myco.+CA)和5组(50 Myco.+CA)组分别在基础饲粮、实验1组和实验2组的基础上添加0.2%CA。采用复合菌种(乳酸菌、酵母菌、枯草芽孢杆菌分别为6.33×106、1.05×106、8.94×106cfu/g)对全价饲粮进行固态发酵,发酵开始前所有处理饲粮水分调节至50%。结果表明:1)本实验条件下,饲粮pH和OM含量随发酵时间显著下降(P0.05),而NH_3-N和乳酸水平随发酵时间显著升高(P0.001)。2)饲粮(0 d)的pH和NH_3-N水平均随镰刀菌毒素水平升高显著降低(P0.001)。发酵末期(18 d)对照组pH和NH_3-N显著低于两个毒素组(P0.001),乳酸含量则随毒素水平升高显著降低(P0.001)。发酵全程平均的pH和乳酸含量随毒素水平升高显著降低(P0.001);对照组发酵全程的平均OM显著低于50%毒素组(P=0.044)。对照组发酵全程的平均NH_3-N显著低于两个毒素组(P0.001)。3)添加CA的全程平均pH显著低于不添加CA组(P=0.018)。4)镰刀菌毒素和CA对发酵12 d(P=0.027)的乳酸具有显著的交互作用。5)pH与OM、OM与NH_3-N、NH_3-N和乳酸呈显著正相关(P0.05),而pH与NH_3-N、pH与乳酸、OM与乳酸呈显著负相关(P0.05)。本实验条件下镰刀菌毒素及其水平显著影响全价饲粮发酵参数pH、OM、NH_3-N和乳酸水平,添加CA显著影响发酵全程的平均pH,且镰刀菌毒素和CA对乳酸(12 d)具有显著的交互作用。     

玉米蛋白粉日粮纤维和能量对猪氮代谢的影响

平均体重 5 0 .9kg生长猪 ,采用全收粪法 ,6× 6拉丁方试验设计 ,测定不同种类的玉米蛋白粉日粮纤维和能量对生长猪氮代谢的影响。试验结果 :玉米蛋白粉 (CP :5 2 % )、玉米蛋白粉 (CP :47.4% )、玉米蛋白粉 (CP :32 % ) 3种日粮 ,氮的消化率分别为 87.9% ,88.9% ,89.7% ;总氮利用率分别为 5 2 .6 4% ,49.0 2 % ,37.86 % ;粪氮与日粮氮比值分别为 12 .0 % ,11.1% ,10 .5 %。玉米蛋白粉日粮的氮沉积量、氮消化率、总氮利用率与日粮的NDF ,ADF ,CF的消化率呈线性正相关。日粮的粪氮与日粮氮比值 ,同日粮的NDF ,ADF ,CF的消化率呈线性负相关 ,同日粮的NDF或CF含量呈线性正相关     

固态发酵玉米黄粉饲料复合菌种的筛选

运用平板点种法、点种刺激圈法和多菌种固体发酵法3种主要方法,筛选发酵玉米黄粉饲料的复合菌株。结果表明,枯草芽孢杆菌（Bacillussubtilis）、凝结芽孢杆菌（Bacilluscoagulans）和地衣芽孢杆菌（Bacilluslicheniformis）3种菌株以1∶1∶1的比例混合,按5% 的接种量接入发酵培养基,发酵效果较好,于30 ℃条件下发酵120 h,玉米黄粉饲料中可溶性蛋白含量由3.78%提高到14.26%。