玉米芯的营养成分分析

本文主要分析了甜玉米、超甜玉米、两种糯玉米煮熟前后共8个样品的玉米芯的营养成分。实验结果表明,除水分外,纤维素、淀粉是玉米芯的主要成分,其中甜玉米芯的纤维素含量最高,可达0-3g佗;糯玉米芯淀粉含量比非糯型高50％,经蒸煮之后,糊化作用导致糯玉米芯的的淀粉损失率为50％;玉米芯的多酚含量≤1．34μg／g,而黄酮的含量最高可i态到0．05mg／g;8种玉米芯的氨基酸含量基本接近,其中以谷氨酸和脯氨酸含量最高,蛋氨酸和络氨酸含量最低,熟的甜玉米芯所含的氨基酸总量最高,为14．94mg／g,必需氨基酸含量占31．88％;玉米芯中矿质元素丰富,cu含量最高,为5．61-24．23mg／g,其次则是K和Mg。     

果胶酶处理对甜玉米芯可溶性糖含量的影响

为提高甜玉米芯总糖产量,对甜玉米芯进行果胶酶水解。采用单因素实验考察酶添加量、pH、温度以及时间对果胶水解度的影响,采用响应曲面法分析建立二次回归模型。结果表明,果胶水解的最佳条件为:酶添加量88 U/g,温度60 ℃,pH5.0,时间90 min,此时果胶水解度为43.82%±0.02%。分别取果胶酶处理前后甜玉米芯进行可溶性糖含量对比分析,果胶酶处理前可溶性糖含量为53.16%±0.02%,果胶酶处理后为62.89%±0.03%,可溶性糖含量提高了9.73%。     

水稻秸秆和玉米芯栽培料对棕色蘑菇子实体营养成分的影响

测定水稻秸秆和玉米芯2 种栽培料上生长的棕色蘑菇和双孢菇子实体中营养成分和氨基酸含量。采用蛋白营养评价方法,对2 种蘑菇的营养价值进行全面评价。结果表明,水稻秸秆栽培料上生长的棕色蘑菇粗纤维和游离氨基酸含量较高,分别为12.46%和12.11%;玉米芯栽培料上生长的棕色蘑菇粗蛋白质含量高达45.03%;同种栽培料条件下棕色蘑菇粗蛋白质、灰分、粗纤维含量均高于双孢菇,但总糖、游离氨基酸及可溶性蛋白含量比双孢菇低。2 种栽培料上生长的棕色蘑菇必需氨基酸种类齐全,玉米芯栽培料上生长的蘑菇氨基酸和必需氨基酸总量都高于水稻秸秆栽培料生长的蘑菇,其氨基酸含量比例都接近世界卫生组织/联合国粮食及农业组织推荐的理想模式,其第一限制氨基酸都为蛋氨酸＋半胱氨酸,亮氨酸都为第二限制氨基酸;比较2 种栽培料条件下的子实体蛋白质氨基酸评分、化学评分和营养指数,棕色蘑菇指标均比双孢菇高,且水稻秸秆为栽培料时,棕色蘑菇与双孢菇差异更显著。结果说明,玉米芯为栽培料上生长的棕色蘑菇营养价值优于水稻秸秆。     

脂肪酸的生理作用及其对其他营养成分的影响

详细讨论了脂肪酸的生理作用及其蛋白质,碳水化合物,维生素,矿物质等营养成份的影响。     

木聚糖酶对玉米芯酶水解过程的影响

研究了稀酸预处理过的玉米芯酶水解过程中,木聚糖酶的补充对葡萄糖、木糖得率的影响。结果表明:玉米芯的酶水解过程中,添加适量的木聚糖酶,可提高葡萄糖和木糖的生成速度,但是,酶解24h之后,木聚糖酶的这种强化作用基本消失,此时葡萄糖和木糖生成速度基本上与初始酶用量无关。在总蛋白质含量不变的情况下,采用含等量蛋白质的纤维素酶和木聚糖酶所构成的混合酶系,明显地比单一等量蛋白质的纤维素酶提高了单位蛋白质的产糖率,有利于降低酶解成本。在纤维素酶量为5~35FPU/g(干原料)范围内,适宜的木聚糖酶添加量为60IU/g(干原料);在其他条件相同情况下,分别采用35FPU/g(干原料)的纤维素酶和混合酶系[15FPU/g(干原料)的纤维素酶与60IU/g(干原料)木聚糖酶混合]时,72h时的糖得率(葡萄糖和木糖)几乎相等,因此,采用纤维素酶和少量的木聚糖酶的混合酶系可明显地降低纤维素酶的使用量,降低酶解成本。      

发酵玉米芯对异育银鲫生产性能及鱼体品质的影响

研究了饲料中添加不同水平发酵玉米芯对异育银鲫生长性能、鱼体品质的影响.结果表明:在异育银鲫饲料中添加5%发酵玉米芯,其增重率、总消化率、蛋白质消化率和鱼体粗灰分、钙含量与对照组比差异不显著(P>0.05);随着发酵玉米芯添加水平的提高,增重率、总消化率、蛋白质消化率和鱼体粗灰分、钙含量与时照组比均变化显著(P<0.05).     

食品添加剂对黑糯玉米芯色素稳定性的影响

研究了室温环境下常用食品添加剂对黑糯玉米芯色素稳定性的影响.结果表明:室温环境下,乳酸的pH值越小,色素的稳定性越好,乳酸溶液的温度对色素的稳定性影响不大,光照能加快乳酸中色素的降解;葡萄糖、蔗糖、NaCl、黄原胶、可溶性淀粉对色素有增色作用,山梨酸钾对色素的稳定性影响不大,H2O2、Vc、光照、温度、CMC对色素有减色作用.     

薇甘菊栽培的巨大口蘑营养成分研究

本研究对薇甘菊栽培的巨大口蘑营养成分进行了研究,结果表明:每100 g干的巨大口蘑子实体中总糖、多糖、粗纤维、粗脂肪、粗蛋白、灰分含量分别为54.24 g、13.42 g、5.52 g、1.60 g、15.55 g、6.21 g。巨大口蘑中含有17种人体所需的氨基酸,氨基酸总量为15.13 g/100 g,其中必需氨基酸占氨基酸总量的40.38%,必需氨基酸与非必需氨基酸的比值(E/N)为0.68,符合FDA和WHO提出的理想蛋白质必需氨基酸含量达40%以上,E/N在0.6以上的要求。矿质元素K、Na、Ca、Mg、Cu、Zn、Fe、Mn含量分别为27.58 g/kg、0.24 g/kg、0.23 g/kg、0.90 g/kg、69.72 mg/kg、55.52 mg/kg、51.46 mg/kg、10.05 mg/kg。有毒重金属铅、镉、总砷的含量低于食用菌质量安全要求的重金属含量限量标准。总汞含量有少许超标。这一研究结果为薇甘菊栽培巨大口蘑的进一步开发和利用提供了理论依据,也为薇甘菊的综合防治提供了新方法。     

猪肚菇子实体多糖的分离纯化及抗氧化活性测定

目的：研究多猪肚菇子实体多糖的抗氧化活性。方法：用热水浸提新鲜猪肚菇子实体,乙醇沉淀多糖,Sevag 法去除多糖中的蛋白,DEAE-52 纤维素柱层析、Sephadex S-200 凝胶柱层析进一步纯化,然后进行抗氧化活性测定。结果：DEAE 柱层析纯化后得到两种多糖组分A 和B,Sephadex S-200 凝胶柱层析证实A 为单一组分,组分A 的抗氧化活性测定结果显示其具有抗氧化活性,且抗氧化活性随其质量浓度的升高而升高。结论：分离纯化后的猪肚菇多糖具有抗氧化活性,且活性呈现剂量效应,随质量浓度升高而升高。     

古尼虫草菌丝体维生素E的初步分析

古尼虫草与传统名贵中药冬虫夏草类似,具有多种活性物质及广泛的药理作用,是一种重要的虫草属真菌.分别用30 %、50 %、80 %乙醇溶液和乙酸乙酯作为提取液,从古尼虫草菌丝体中提取维生素E,并用乙酸乙酯萃取的方法进行初步分离,硅胶薄层层析和紫外分光光度法分析粗产物中的维生素E.结果表明,提取物质的总量与提取液的乙醇含量有关,提取液的有机溶剂比例越高,提取到维生素E量越高,但提取的维生素E的纯度越低.初步确定乙酸乙酯为提取虫草维生素E的最适溶剂.     

古尼虫草多糖对衰老模型小鼠的影响

研究古尼虫草多糖的抗衰老作用.将健康小鼠随机分为空白组、模型组、低剂量组、中剂量组和高剂量组,将模型组、低剂量组、中剂量组和高剂量组用D-半乳糖造亚急性衰老小鼠模型;低剂量组、中剂量组和高剂量组的小鼠建模11 d后每天灌胃50%古尼虫草多糖溶液,剂量分别为100 mg/kg、200 mg/kg和400 mg/kg;45 d后观察脑组织中以及血清中超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)活力,丙二醛(MDA)含量.结果表明,古尼虫草多糖可提高小鼠脑组织和血清中SOD(P＜0.01)和GSH-Px(P＜0.01)活力,明显抑制小鼠脑组织和血清中MDA(P＜0.01)的形成.因此,古尼虫草多糖有很好的抗衰老作用.     

Identification and antioxidant activity of anthocyanins extracted from the seed and cob of purple corn (Zea mays L.)

The total anthocyanin content (TAC) and the antioxidant activity of the seed and cob from Chinese purple corn (Zea mays L., cv Zihei) extracts were determined by pH-differential method, and DPPH, FRAP, and TEAC methods, respectively. TAC in purple corn cob anthocyanins (PCCAs) extract was higher than TAC in purple corn seed anthocyanins (PCSAs) extract. Compared to bulylated hydroxytoluene (BHT), PCCAs and PCSAs possessed significantly higher antioxidant activities, according to the DPPH, FRAP and TEAC assays. A satisfactory correlation between TAC and antioxidant activity was observed. Result indicated that cyanidin-3-glucoside, pelargonidin-3-glucoside and peonidin-3-glucoside were components in PCSAs extracts, and seven kinds of anthocyanin had been detected and six kinds of anthocyanin in PCCAs extracts were separated and identified them as cyanidin-3-glucoside, pelargonidin-3-glucoside and peonidin-3-glucoside, and their respective malonated counterparts as their anthocyanins using HPLC–MS analysis.Industrial relevanceIn the last decades, in interest in anthocyanin pigments has increased because of their possible utilization as natural food colorants and especially as antioxidant and anti-inflammatory agents. Purple corn is a pigmented variety of Z. mays L., originally cultivated in Latin America. Now, this corn variety is mainly grown in China, especially in Shanxi and Anhui Province, could be new and interesting sources to obtain extracts rich in anthocyanins for their use in food, pharmaceutical and cosmetic industries. Our results indicated that the seed and cob of purple corn possessed excellent antioxidant activity, which could lead to increased application of these natural food colorants by the food industry.     

玉米胚芽水分含量对其油脂品质的影响

研究了玉米胚芽水分含量对其油脂品质的影响。通过调整玉米胚芽中水分含量,提取其中油脂,研究玉米胚芽水分含量变化对其油脂脂肪酸组成、理化指标、主要有益微量伴随物的影响。结果表明:玉米胚芽水分含量变化对其油脂脂肪酸组成和甾醇含量基本没有影响,但随着玉米胚芽水分含量提高,其油脂酸值、过氧化值、色泽都会升高,生育酚含量下降,并且α-生育酚和γ-生育酚含量变化与玉米胚芽油色泽红值具有良好的相关性。     

Effect of irradiation and germination on selected nutrients of corn

The effect of germination on potential nutrients (mineral matter, protein, lipids, fibre, carbohydrates and total energy) and an antinutrient (phytate) of corn, was studied. The influence of irradiation (5–20 krad) and germination on the vitamin contents (ascorbic acid, riboflavin) was also investigated. Comparison of the coefficients of variability revealed striking differences in the contents of these nutrients as a result of germination. Total mineral matter increased from 1·15% to 1·40%, protein from 9·6% to 14·0%, lipids from 4·36% to 4·60% and fibre from 0·71% to 0·82% whereas phytate decreased from 200 to $\text{105}\text{mg}\text{100}\text{g}$ and carbohydrates from 85·5% to 70·0%. Radiation and germination significantly affected the ascorbic acid and riboflavin contents of corn (p < 0.05). A maximum value of ascorbic acid ($\text{19·4}\text{mg}\text{100}\text{g}$) was observed in the 10 krad treated seeds as compared with $\text{14·3}\text{mg}\text{100}\text{g}$ in the control after 120 h of germination. Similarly, riboflavin increased from an initial value of 1·5 μg/g to 13·1 μg/g in the 20krad sample as compared with 6·0 μg/g in the unirradiated control.     

甜玉米籽粒及其芯风味成分分析

采用顶空-固相微萃取和气相色谱-质谱联用技术,对市售的鲜甜玉米及其玉米芯中挥发性风味成分进行研究。以甜玉米的挥发性风味成分中相对含量较多的物质作为评价指标,在一定的顶空固相微萃取条件下,对其主要成分进行鉴定和分析。萃取条件为:样品在萃取瓶中于60℃预热35 min,采用以碳分子筛/聚二甲基硅氧烷为涂层的萃取头在60℃下萃取35 min。结果表明,本试验在玉米中共检测鉴定出24种挥发性物质、在玉米芯中共检测鉴定出20种挥发性物质,其中与甜玉米气味相关的成分主要是相对分子质量为80～140的C4～C9挥发性羰基化合物、酯类、醇类、芳香族化合物、呋喃类、烃类物质,这些挥发性成分的协同作用构成了鲜甜玉米的特征风味。     

H2O2催化预处理对玉米芯酶解的影响

木糖通常经半纤维素水解而得,而富含半纤维素的玉米芯细胞中同时也含有木质素与纤维素,与半纤维素紧密缠绕．阻碍了其水解,因此预处理便成了生产木糖过程中的一个必要的步骤。经实验优化所得预处理最佳工艺条件为：室温,固一液比1：20,pH5．0,H2O2量3．05％,Fe^2＋添加量0．15g,处理时间2．56h。在此条件下H2O2催化预处理后,用木聚糖酶进行酶解,木糖和葡萄糖得率分别比未处理的0．1895、0．1672g／g玉米芯提高到0．2676、0．2930g／g玉米芯。而经木聚糖酶和纤维素酶（双酶）进行酶解后又分别提高到0．2856、0．3321g／g玉米芯,证明H2O2催化预处理是一种有效可行的预处理方法     

国产玉米毛油主要脂肪酸含量的分析

经过对全国各区域2 246个玉米毛油样品进行脂肪酸组分检测,分析研究了玉米毛油中主要脂肪酸组分的含量范围,其中棕榈酸11.5%~13.5%、硬脂酸1.5%~2.0%、油酸28.0%~34.0%、亚油酸50.0%~57.0%、亚麻酸0.50%~0.80%,检测结果符合国标中的质量指标要求。通过比较,国产玉米毛油的主要脂肪酸组分含量范围较为集中,有利于企业进行油种的识别和对产品质量进行控制和改善。     

Thermal degradation kinetics of aqueous anthocyanins and visual color of purple corn (Zea mays L.) cob

Purple corn cob was the byproduct during the corn processing. Thermal degradation kinetics and Hunter color parameters (a, b, C, h° and ΔE) of aqueous anthocyanins from purple corn cob were studied at selected temperatures (70 °C, 80 °C and 90 °C) at pH 4.0. The results indicated that the thermal degradation of anthocyanin and Hunter color C, a and ΔE parameters followed the first-order reaction kinetics, while Hunter color h° and b parameters followed zero-order reaction kinetics. The calculated values of activation energies (Ea) were 18.3, 35.9, 37.1, 31.6, 34.9 and 30.0 kJ/mol for anthocyanins, C, a, ΔE, h° and b parameters, respectively. The higher Ea indicated that greater temperature sensitivity of visual color as compared to anthocyanins content. The degradation of anthocyanins showed positive correlation with C (R² > 0.909), a (R² > 0.860) and ΔE (R² > 0.940), while the degradation of anthocyanins showed negative correlation with h° (R² > 0.828) and b (R² > 0.735) during heating.

Industrial relevance

Purple corn cob was the byproduct during the corn processing. Purple corn cob is dark purple to almost black color due to its high content of anthocyanins, which makes this byproduct a good source of anthocyanins. In this study, the excellent linear correlation between Hunter color parameters (a, b, C, h° and ΔE) and content of anthocyanins showed that the Hunter color parameters may also be used instead of anthocyanins content during heating. The advantage of using the visual Hunter color parameters may be measured as on-line quality control parameters during thermal processing of food industry.