Characterization of the Jagged Stress-strain Relationships of Puffed Extrudates using the Fast Fourier Transform and Fractal Analysis

The jaggedness of the stress-strain relationship of two kinds of puffed extrudates stored under different humidity conditions was assessed by the power spectrum of the Fast Fourier Transform and the Natural Fractal dimension of normalized compression curves. Both analyses, performed with a micro-computer, provided a consistent measure of jaggedness. The apparent Fractal dimension, obtained using the Blanket algorithm, was the most convenient measure of overall ruggedness since it was expressed by a single number. The power spectrum that resulted from the Fourier transform, however, could be used to identify the length scale of structural features where fracture takes place, and its shape could be more directly related to structural features and textural properties.     

Crunchiness Loss and Moisture Toughening in Puffed Cereals and Snacks

Upon moisture uptake, dry cellular cereals and snacks loose their brittleness and become soggy. This familiar phenomenon is manifested in smoothing their compressive force–displacement curves. These curves’ degree of jaggedness, expressed by their apparent fractal dimension, can serve as an instrumental measure of the particles’ crunchiness. The relationship between the apparent fractal dimension and moisture content or water activity has a characteristic sigmoid shape. The relationship between the sensorily perceived crunchiness and moisture also has a sigmoid shape whose inflection point lies at about the same location. The transition between the brittle and soggy states, however, appears sharper in the apparent fractal dimension compared with moisture plot. Less familiar is the observation that at moderate levels of moisture content, while the particles’ crunchiness is being lost, their stiffness actually rises, a phenomenon that can be dubbed “moisture toughening.” We show this phenomenon in commercial Peanut Butter Crunch® (sweet starch‐based cereal), Cheese Balls (salty starch‐based snack), and Pork Rind also known as “Chicharon” (salty deep‐fried pork skin), 3 crunchy foods that have very different chemical composition. We also show that in the first 2 foods, moisture toughening was perceived sensorily as increased “hardness.” We have concluded that the partial plasticization, which caused the brittleness loss, also inhibited failure propagation, which allowed the solid matrix to sustain higher stresses. This can explain other published reports of the phenomenon in different foods and model systems.     

常见6种杂粮与2种主粮的抗氧化活性比较研究

目的：比较常见6种杂粮：荞麦(甜荞、苦荞)、小米、糜米(粳性、糯性)、玉米、薏米、燕麦与2种主粮：大米、小麦食用部分的总酚、黄酮含量及其存在形式和抗氧化活性差异,并分析总酚、黄酮含量与抗氧化活性之间的相关性。方法：采用Folin-Ciocalteu法测定总酚含量,NaNO2-Al(NO)3测定黄酮含量;DPPH自由基法、ABTS+ ·法、β-胡萝卜素-亚油酸乳化液法和还原力法评价样品的抗氧化能力。结果：总酚含量由高至低为：苦荞、甜荞、燕麦、薏米、玉米、小米、粳性糜米、小麦、糯性糜米、大米,并且除小米、糯性糜米外其他样品提取物的多酚主要以自由态存在,占总酚的64.18%～98.70%;黄酮含量最高的为薏米、燕麦次之,且均多以自由态存在;杂粮的抗氧化活性高于主粮,其中苦荞清除DPPH自由基能力、ABTS+ ·能力和总还原力最强,甜荞次之,而小米抑制β-胡萝卜素褪色能力最强;同时,抗氧化活性与总酚含量之间具有良好的线性关系,与黄酮含量的相关性不明显。结论：杂粮的总酚含量及总抗氧化活性高于主粮,其中苦荞最为突出,因此,推荐增加日常杂粮食用量以弥补主粮膳食中多酚物质含量过低的不足。     

Mathematical Characterization of the Compressive Stress-Strain Relationships of Spongy Baked Goods

The compressive stress-strain relationships of selected breads, English muffins and sponge cake were determined with a Universal Testing Machine and described mathematically in terms of a three-parameter empirical model. These parameters gave account of the overall mechanical resistance of the sponge, the existence of a shoulder in its stress-strain curve and the strain level at which densification of the sponge becomes the dominant deformation mechanism. They were also sensitive indicators of the changes that were observed in the stress-strain relationship as a result of successive compression and could be used to distinguish between the deformation patterns of the various products.     

"双曲生料发酵"酿制混合谷物酒的研究

实验研究了一种新的生料发酵方法.结果表明:在大米、玉米、高粱与小麦原料的混合生料发酵过程中加入另一种自制的芳香酒曲,酒的香味和品质得到明显改善,出酒率保持在高水平上.发酵温度,料水比影响发酵时间和出酒率.     

Ascorbic Acid Fortification Reduces Anthocyanins in Extruded Blueberry-Corn Cereals

ABSTRACT: Corn meal was mixed with ascorbic acid (0%, 0.1%, and 1%, wt/wt) and sucrose (15%) or lowbush blueberry concentrate (17%), and twin-screw extruded to produce ready-to-eat breakfast cereals. Consumers evaluated selected samples using just-right scales. Extrusion decreased anthocyanins in blueberry cereals; ascorbic acid was retained better in cereals containing blueberry concentrate than in the sweetened corn cereals. Blueberry concentrate decreased expansion ratio and increased bulk density. Based on sensory scores, blueberry extrudates with 0.1% ascorbic acid could be acceptable if sweetness is increased.     

粮谷中三环唑残留量的液相色谱-质谱/质谱检测

本文建立了玉米、大麦、糙米、大米、小麦五种粮谷基质中三环唑残留量的液相色谱-质谱／质谱检测方法。样品经丙酮涡旋振荡提取,再经中性氧化铝固相萃取柱净化后,由液相色谱-质谱／质谱检测,外标法定量。方法的定量限为0.01 mg/kg,标准品浓度在2.5 ng/mL~80 ng/mL呈良好的线性关系,相关系数大于0.99。 粮谷样品在0.01、0.02和3.00 mg／kg添加水平的回收率范围分别为72.1%~95.6%,73.0%~95.4%,80.1%~99.2%,相对标准偏差范围在2.2%~7.4%。本方法方便、快速、溶剂消耗低、灵敏度高、回收率稳定,可以满足进出口粮谷中三环唑残留量的检测需求。     

阿拉伯木聚糖对谷物食品的品质影响研究进展

阿拉伯木聚糖是谷物中广泛存在的一种非淀粉多糖,具有独特的物理化学性质和营养价值,对谷物产品的加工和最终产品的品质有较大的影响。作者综述了阿拉伯木聚糖对谷物产品加工性能的影响及其机制,同时分析了其对最终产品品质的影响,以期为高品质谷物食品尤其是全谷物食品的开发提供依据。     

谷物中伏马菌素B1酶联免疫分析法的建立

以匙孔血蓝蛋白(KLH)为载体,采用碳化亚二胺法人工合成伏马菌素B1(FB1)抗原FB1-KLH,免疫大白兔获得特异性良好的抗FB1 多克隆抗体;在多克隆抗体的基础上建立伏马菌素B1 的间接竞争酶联免疫吸附分析方法,该方法IC50 为11.7μg/L,最低检出限1.1μg/L,平均批内和批间变异系数分别为5.8%、10.2%;分析不同溶剂对标准曲线和加标回收率的影响,确定PBS 溶液为样本最佳提取溶剂;在玉米、小麦、大米、高粱谷物样本中添加50～500μg/kg 的FB1 标准品,平均回收率在70.5%～105.6% 之间。将该方法应用于40 份谷物样本中FB1 的检测,检测结果与高效液相色谱的相关系数(R2)为0.9547。该方法简单、灵敏、快速、准确,适用于谷物中FB1 的检测。     

杂粮营养工程米的干燥及蒸煮特性研究

干燥参数的合理控制对杂粮营养工程米的品质有重要影响。通过单因素及正交试验,确定杂粮营养工程米的干燥工艺参数为热风温度50℃、风速0.4m/s、装载厚度1.0kg/m2。同时,对干燥后的成品进行蒸煮特性研究,结果表明：杂粮营养工程米浸泡20～40min,再按1:1(m/m)的米水比进行加热蒸煮,加热停止后,保温15～30min,可得食味较佳的杂粮营养工程米饭。     

Extrudate Cell Structure-Texture Relationships

Corn-based extrudates that ranged widely in mean cell size and density were produced by varying extrusion moisture and RPM and also by the addition of rice flour, citric acid, tricalcium phosphate, sodium bicarbonate, and gluten. Cell sizes were measured using an Olympus image analysis system and mechanical properties, including breaking stress and plateau stress values achieved during compression, were measured using an Instron. Breaking and plateau stresses were negatively dependent on mean cell size and positively dependent on density in pure corn samples but the form of the relationship was altered by the presence of additives in the extrudates.     

Cell Size Distributions of Puffed Corn Extrudates

The cell size distributions of various experimental puffed corn extrudates were determined by image analysis, applied to longitudinal and transversal cross sections. Individual cell cross-sectional area was used as the size measure. All the cell size distributions, regardless of specimen orientation, composition and extrusion conditions, were described mathematically by both the log-normal and Rosin-Rammler distribution functions. The distributions mean size, degree of skew-ness or the corresponding distribution functions constants, were characteristic of the extrudate type and its particular cellular structure.     

Bioavailability for Rats of Vitamin E from Fortified Breakfast Cereals

Bioavailability of vitamin E in three fortified breakfast cereals and dose-response relationships among dietary vitamin E and selected biochemical indices were investigated using a rat depletion-repletion model. Response criteria included concentrations of α-tocopherol in plasma, red blood cells, liver, heart, and adipose tissue, and plasma pyruvate kinase activity. Bioavailability of vitamin E in whole grain cereal and corn flakes was generally comparable to that of the tocopheryl acetate standard. Bioavailability of vitamin E in bran flakes was lower than that of the standard based on four of the criteria. A food matrix effect in bran flakes resulted in the lower bioavailability.     

马铃薯膨化饼的研制

对马铃薯膨化食品的配料和生产工艺进行研究,结果表明,原料成分比为70%薯泥(水分含量为80%)、薯粉为4%、糯米粉为8%、粳米粉为18%,干燥后的坯料水分含量在5%～8%,油炸温度为240℃,所得产品呈黄色,膨化效果好且有干爽的马铃薯风味。     

稻谷堆的压缩密度与体变模量的测定与分析

利用应变控制式三轴仪对稻谷堆的压缩密度与体变模量进行了测定,并分析了围压对稻谷堆压缩密度的影响以及围压和含水率对稻谷堆体变模量的影响。结果表明:同一含水率(11.50%、13.14%、14.47%、15.86%、17.37%)下,稻谷堆的压缩密度随着围压(23~188 kPa)的增大而增大,其变化范围分别为0.664 6~1.067 9 g/cm3、0.670 8~1.081 5 g/cm3、0.678 1~1.084 2 g/cm3、0.681 4~1.142 3 g/cm3、0.686 1~1.168 8 g/cm3;稻谷堆的体变模量随着围压(23~188 kPa)的增大而增大,其变化范围分别为311.52~495.06kPa、294.73~487.80 kPa、291.61~450.05 kPa、210.34~430.04 kPa、160.16~301.07 kPa;同一围压下,稻谷堆的体变模量随着含水率的增大而减小,并可拟合出回归方程k=-aW2+bW-c,式中:W为含水率,k为体变模量,且a,b,c随着围压的不同而变化。     

早餐谷物研究进展Ⅲ.挤压过程中原料成分变化

该文详细论述早餐谷物原料中主要成分,如蛋白质、淀粉、脂类物质、膳食纤维及其它成分在挤压过程中所发生变化。     

Effects of Dietary Fiber from Shredded and Puffed Wheat Breakfast Cereals on Intestinal Function in Rats

Rats were fed a semi-purified diet containing 63% puffed wheat (PW) or 63% shredded wheat (SW) breakfast cereals for 6 wk. A 16% unprocessed wheat bran (WB) diet was used as control. The neutral detergent fiber (NDF) content was 3.2%, 1.9%, and 1.9% in diets PW, SW, and WB, respectively. Feces were collected during three 96-hr periods: fecal weight and volume were lower (P < 0.001), fecal density was higher (P < 0.001), and intestinal transit time was longer (P < 0.01) in group PW than in groups SW and WB. Results indicate that the dietary fiber content of puffed wheat breakfast cereals is lower than that of shredded wheat breakfast cereals.     

高效液相法同时检测谷物中玉米赤霉烯酮和赭曲霉毒素A

该研究开发一种快速、灵敏同时检测玉米、小麦和稻米中玉米赤霉烯酮(zearalenone,ZEN)和赭曲霉毒素A(ochratoxin A,OTA)的高效液相色谱检测方法。将样品采用乙腈/水(80/20,体积比),200 r/min,30℃振荡提取30 min后,经Oasis PRiME HLB固相萃取柱净化后,上样检测。该方法ZEN和OTA检测限(limit of detection,LOD)为3.7μg/kg和0.11μg/kg,定量限(quantification Limit,LOQ)为12.25μg/kg和0.38μg/kg,线性范围分别为10μg/kg^2000μg/kg和0.2μg/kg^200μg/kg,加标样品中不同浓度的ZEN和OTA回收率为83.0%~101.3%,日内精密度和日间精密度分别为3.12%~7.03%和3.57%~9.3%。该方法适用于玉米、小麦和稻米中ZEN和OTA的同时检测。     

量子点标记免疫层析试纸条快速检测谷物中赭曲霉毒素A

目的:根据竞争抑制免疫层析原理,构建一种基于量子点标记的免疫层析试纸条用于检测谷物中赭曲霉毒素A(Ochratoxin A,OTA)的残留量。方法:通过活化酯法将羧基功能化的量子点(Quantum dot,QD)与赭曲霉毒素A多克隆抗体(Antibody,Ab)偶联制备量子点抗体偶联物(QD-Ab);通过分别添加不同量的QD-Ab和工作液,优化量子点标记免疫层析试纸条的工作条件;通过商品化试剂盒验证该方法的有效性。结果:当QD与Ab的摩尔比为1:10时,QD-Ab荧光特性最佳;在QD-Ab和工作液添加量分别为1、10 μL时,量子点标记免疫层析试纸条结果最佳;量子点标记免疫层析试纸条的检测限为0.5 μg/L,谷物样品中的检测限为5 μg/kg,整个检测过程不超过10 min;量子点标记免疫层析试纸条特异性良好且具有有效性。结论:该方法操作简便、检测快速、结果准确灵敏,易于判断,可以满足谷物中赭曲霉毒素A残留量现场快速检测的要求。     

降低挤压杂粮营养工程米黏附性的工艺优化

通过单因素试验和响应面分析确定挤压杂粮营养工程米黏附性的优化工艺参数。结果表明,螺杆转速32.6r/min、机筒温度分布109.3～119.3～129.3℃、物料加水质量分数为22.6%,在此优化条件下,挤压杂粮营养工程米黏附性的优化值为－ 375.278178g·s。验证实验表明,黏附性实验值与优化值接近,且优于市售普通大米(－ 394.678g·s),接近于市售魔芋挤压工程米(－ 346.487g·s),说明该优化结果可靠。通过感官评定,其综合食用品质接近市售普通优质大米,优于市售魔芋挤压工程米。