Extruded Potato Peel Functional Properties Affected by Extrusion Conditions

Extrusion cooking of potato peel waste from processing plants to im-prove food safety affects functional properties of these peels as a high-fiber ingredient in foods. The effects of barrel temperature (104°C and 143°C) and feed moisture (31, 33.5, and 36% d.b.) on extruder performance and physical and functional properties of peels were studied. Torque and die pressure decreased with barrel temperature; all variables affected melt temperature. Samples were darker at the higher temperature. Expansion, Hunter a, and powder bulk density decreased with both variables. Hydration capacity increased with feed moisture. Extruded peels differed from commercial fiber products in color, but hydration capacity was similar among extruded peels and cereal brans.     

EFFECT of EXTRUSION ON TRYPSIN INHIBITOR CONTENTS of SOY-SWEET POTATO MIXTURES

Mixtures of soy and sweet potato ( Ipomoea batatas ) (L.) Lam), flours containing 18%, 25% and 30% moisture, respectively, were extruded in a single screw extruder. Results showed that inactivation of trypsin inhibitor was enhanced by both reductions in feed moisture and soy flour contents of sample mixtures. Hence subsequent extrusion was carried at 18% feed moisture with variable feed ratio, screw rotation speed and die diameter, using a central composite rotatable, near orthogonal experimental design. Results further showed that the effect of increasing the ratio of soy in the mixture was linearly significant (p > 0.05). Optimum Trypsin Inhibitor (TI) inactivation value of 3.40 mg/g was predicted at a feed composition of 80% sweet potato, 9 mm die diameter and 154 rpm, respectively.     

薯类原料膨化特性及其膨化粉品质特性

本实验以4 种薯类全粉（马铃薯、紫马铃薯、甘薯、紫甘薯）为原料,考察了不同薯类原料样品的膨化特 性,并采用质构仪、快速黏度分析仪及稳定性分析仪对不同薯类膨化粉的品质特性进行研究。结果表明：4 种薯类 原料中,马铃薯类原料膨化特性显著优于甘薯类原料,其中马铃薯样品膨化度、糊化度以及水溶性指数较高,容积 密度较低,膨化性能最好;相关性分析表明,不同薯类原料膨化特性的差异与物料基本组分的变化率有关;马铃薯 类原料坚实度、稠度、低谷黏度、回生值及回生值/峰值黏度显著低于甘薯类原料,说明马铃薯类膨化粉熟化度高、 口感好,其中马铃薯样品显著优于紫马铃薯（P＜0.05）;稳定性分析仪图谱及稳定性动力学指数均显示马铃薯类原 料的分散稳定性显著优于甘薯类原料,其中马铃薯样品显著优于紫马铃薯（P＜0.05）。综上可知,4 种薯类原料中, 马铃薯类原料膨化特性及其膨化粉品质特性整体显著优于甘薯类原料,其中马铃薯样品性能最佳。     

Physical, chemical and nutritional quality of extruded corn germ flour and milk protein blends

An expanded nutrient snack was prepared by extrusion cooking of defatted corngerm flour added with increasing amounts of milk proteins. Two extrusion temperatures (150 and 170°C) were considered. Physical, chemical and nutritional characteristics of the final product were evaluated. The products extruded at 150°C showed better expansion and crispness than the ones obtained at 170°C. A small addition of milk protein (5%) improves the organoleptic characteristics of the extrudates produced at 150°C. On the contrary the addition of milk protein has a negative influence on the product expansion and consistency of the samples extruded at 170°C.     

Physical Properties of Extruded Products as Affected by Cheese Whey

Corn, rice and potato flour were extruded with sweet whey solids (SWS) or whey protein concentrate (WPC) using low and high shear extrusion processing conditions. WPC added at product content of 25% had minimal effect on the texture of extruded products. Expansion and breaking strength were improved in some processes through changes in extrusion shear and moisture. Whey product incorporation resulted in reduced specific mechanical energy input to the process. Increasing whey product concentration beyond 25% reduced expansion and water absorption indices significantly, affecting textural hardness. Product quality characteristics were directly related to the whey product content.     

Effect of extrusion on the antioxidant capacity and color attributes of expanded extrudates prepared from purple potato and yellow pea flour mixes

Abstract: Foods with antioxidant capacity provide protection against cardio‐vascular, certain forms of cancers, and Alzheimer's diseases caused by oxidative damages and contribute health benefits. The effect of extrusion cooking on the antioxidant capacity and color attributes of extruded products prepared from 3 selected formulations of purple potato and yellow pea flours using a co‐rotating twin screw extruder were studied. Expansion ratios of the extruded products varied from 3.93 to 4.75. The total antioxidant capacities (TAC) of the extruded products, using DPPH assay, were 3769 to 4116 μg trolox equivalent/g dry weight sample and not significantly different (P > 0.05) from their respective raw formulations. The total phenolic contents (TP) of the extruded products varied from 2088 to 3766 μg of gallic acid equivalent/g dry weight sample and retained 73% to 83% of the TP from the raw formulations after extrusion. The total anthocyanins contents (TA) in the extrudates were 0.116 to 0.228 mg of malvidin‐3‐glucosides/g dry weight sample. Compared with their raw formulations, significant losses (60% to 70%) of the TA in the extruded products occurred due to extrusion cooking. Browning indices and color attributes such as brightness, chroma, and hue angle agreed with degradation of anthocyanins in the extruded products. However, extrusion cooking retained antioxidant capacities of the raw formulations in the extruded products either in their natural forms or degraded products with radical scavenging activity. This study demonstrated the potential for the production of puffed extruded food products with the improved antioxidant content from colored potatoes and pulse formulations.     

Stability of zearalenone during extrusion of corn grits

The effects of extrusion cooking on the stability of zearalenone (ZEN) in spiked (4.4 microg/g) food-grade corn grits were investigated using a twin screw extruder. A ground rice culture material containing a high level of ZEN was used to spike the corn grits. The extrusion variables were screw type (mixing and nonmixing), temperature (120, 140, and 160 degrees C), and moisture content (18, 22, and 26%). Both unextruded and extruded samples were analyzed for ZEN by high-performance liquid chromatography. Extrusion cooking of the corn grits resulted in significant reductions of ZEN in grits extruded with either mixing screws or nonmixing screws, but use of mixing screws was somewhat more effective (66 to 83%) overall than nonmixing screws (65 to 77%). Greater reduction of ZEN was observed at either 120 or 140 degrees C than at 160 degrees C. The moisture content of corn grits was not a significant factor affecting reduction of ZEN during extrusion with either mixing or nonmixing screws.     

Influence of modified starches on the stability of beef jerky analogs during storage

ABSTRACT: Textural stabilization of extruded beef jerky analogs (BJA) by using modified starches was studied. From a series of modified starches studied, Frigex W and Instant Pure Flo were identified to show very reduced retrogra-dation, both in gels and after extrusion. These starches were used as textural stabilizers for BJA, an extruded product obtained from potato granules and ground beef. The partial substitution of potato granules with modified starches, at a level of 5% of the formulation, led to increased moisture sorption capacity of the analogs. After a storage period of 1 mo, the samples that contained modified starch had a degree of swelling with 30% higher and much lower elastic modulus as compared to those that contained only potato starch.     

Improving the nutritional performance of gluten-free pasta with potato peel autohydrolysis extract

The potato processing industry produces peels, a good source of fibres, minerals and antioxidants, which could be recovered and used in the production of added-value products, such as gluten-free (GF) foods especially designed for the celiac population.This work is focused on the application of the bioactive fraction extracted from potato peels into GF pasta. Subcritical water extraction (autohydrolysis, AH) was performed on potato peel, and the obtained AH liquid extract was characterized in terms of total phenolic content and antioxidant activity. The selected AH temperature (220 °C at 2.2 MPa) was applied to peels from Kennebec, Neiker and Agria potato varieties, and the Agria extract was selected for application in GF pasta, as this was the one with higher antioxidant activity.The impact of Agria potato peel autohydrolysis extract on the nutritional composition and cooking quality of pasta was assessed. Results confirmed that the GF pasta enriched with potato peel extract presented suitable technological properties, coupled with attractive colour and with increased total phenolic content and antioxidant activity, which can contribute to improve the offer of GF products in the market.     

The physico-chemical characteristics of extruded snacks enriched with tomato lycopene

Adding tomato derivatives to traditional starchy extruded snacks can improve their nutritional properties by adding lycopene and fibre; however the physico-chemical properties of these products must also be considered. Ingredients and extrusion parameters, including temperature, alter these properties, but their effect on lycopene content is not known. In this study, crisp low density extruded snacks were manufactured from corn, wheat and rice, with or without dried tomato skin or paste powder extruded at temperatures of 140, 160 or 180 °C. Lycopene content and the physico-chemical properties (expansion, density, hardness, colour parameters and percentage of moisture loss) of the extruded products were measured. Lycopene retention was higher in products containing tomato skin powder and significantly lower when wheat flour was used to make the snacks. Increases in the processing temperature improved the physico-chemical characteristics of the snacks but had no significant effect on lycopene retention (P > 0.05).     

湘味甘薯挤压膨化食品配方研究

以甘薯全粉和小麦粉为主要原料,研制一种新型湘味甘薯挤压膨化熟食。从甘薯全粉、小麦粉、物料水、食盐添加量等方面对湘味甘薯挤压膨化熟食产品品质的影响进行研究,试验得出湘味甘薯挤压膨化熟食的最佳配方为：36.77%甘薯全粉、36.77%小麦粉、18.57%水、6.98%食盐、0.91%复合料。     

Nutritional Quality of Hard-to-cook and Processed Cowpea

Hard-to-cook (HTC) defect was induced in cowpea seeds by storing at 37°C and 85% relative humidity (RH) for 6 wk. HTC and control (stored at 7°C, 60% RH) seeds were boiled for 45 and 90 min or ground to flour. Flour was cooked as paste or extruded (20% H₂O, 150°C). Overall dietary quality was estimated as Feed Efficiency and Relative Response Ratio. Protein quality was determined as Nitrogen Efficiency and Relative Nutritive Value. Overall and protein nutritional quality were generally higher for control than for HTC cowpea diets. Processing affected control and HTC seeds differently. Boiling either control or HTC whole seeds improved both overall and protein quality compared to raw seeds, while extrusion substantially increased the quality of control seeds but reduced the quality of HTC seeds. Cooking as paste improved protein and overall quality of control seeds but not protein quality of HTC seeds.     

Extrusion cooking of barley flour and process parameter optimization by using response surface methodology

BACKGROUND: The nutritional profile of barley places it in a prime position for development of a new extruded–expanded snack food with health benefits. It was therefore the aim to investigate the effect of extrusion processing variables on system parameters (specific mechanical energy, die pressure and die melt temperature) and physical properties (expansion, bulk density, texture and color) of barley flour extrudates and to optimize processing conditions for production of extruded snack food from barley flour by response surface methodology. RESULTS: Barley flour with 219.7 g kg^?1 moisture content was extruded at different die temperatures (140–160 °C) and screw speeds (150–200 rpm) through a co‐rotating twin‐screw extruder. The system parameters as well as product responses were mainly dependent on temperature, whereas the screw speed imparted a lesser effect. Extrudates produced under extrusion conditions of 160 °C, 150 and 200 rpm and at 164 °C and 150 rpm had higher preference levels of appearance, taste, texture and overall acceptability than that of other selected extrudates for sensory analysis. The optimal conditions for minimum bulk density and desired textural characteristics and color of extrudates correspond to a temperature of 156 °C and screw speed of 166 rpm. CONCLUSION: The results suggested that use of barley flour in extruded snack products offers a desirable variation in diet and can take advantage of the nutritional quality of barley. Copyright © 2008 Society of Chemical Industry     

Physical properties, molecular structures, and protein quality of texturized whey protein isolate: effect of extrusion moisture content

To explore the complex relationship between processing conditions and functional and nutritional properties of food products containing whey protein isolate (WPI), we investigated the effect of extrusion texturization at various temperatures (50, 75, and 100°C) and varying moisture levels of the feed (20, 30, 40, and 50%) on changes in the composition, molecular structure, and protein quality of the extrudates. Bradford assay methods were used to determine protein solubility of the extruded WPI as a function of changing level of moisture. Protein compositional changes as a function of extrusion conditions were quantitatively characterized and analyzed by sodium dodecyl sulfate-PAGE and reversed-phase-HPLC techniques. We showed that at a given temperature, increasing the extrusion moisture content resulted in a slight increase in the overall protein water solubility (at 50 and 75°C), averaging approximately 5% per 10% increase in moisture content. A reduction in β-lactoglobulin content was observed at 50°C with increasing moisture content, indicative of the sensitive nature of β-lactoglobulin to extrusion treatment, whereas the amount of α-lactalbumin remained unchanged at all moisture contents used at a set temperature. The protein quality of the extruded WPI, determined chemically by available sulfhydryl and primary and secondary amines, remained relatively unchanged as a function of moisture level. Circular dichroism and intrinsic tryptophan fluorescence spectroscopic studies revealed considerable structural changes, both at the secondary structural level and the tertiary contacts as a function of increasing temperature, and higher moisture levels can slightly preserve secondary structures but not the tertiary contacts of the protein molecules. Atomic force microscopy provided direct visualization of the fine difference of the protein particles caused by changing extrusion moisture contents, which is in close agreement with the results obtained using other techniques in this work.     

挤压处理对马铃薯全粉加工特性及微观结构的影响

采用挤压法对马铃薯全粉进行挤压处理,考察挤压温度、物料水分质量分数对马铃薯全粉加工特性及马铃 薯全粉面团弹性的影响,通过单因素试验确定最佳挤压工艺参数,采用扫描电子显微镜、差示扫描量热仪、快速黏 度测定仪、X射线衍射仪等仪器,对挤压处理前后马铃薯全粉的微观结构、热力学性质、糊化特性及结晶度变化等 进行对比分析。结果表明：当挤压温度为150 ℃、物料水分质量分数为35%时,马铃薯全粉的加工特性综合比较最 优,溶解度较高,持水性最好,冻融稳定性较好,此时马铃薯全粉面团弹性最好;挤压处理后的马铃薯全粉表面微 观结构出现褶皱,比表面积增加;热稳定性减弱,凝胶性减弱,不易回生;挤压处理使马铃薯全粉的结晶度下降。     

Heated Ascorbic/Citric Acid Solution as Browning Inhibitor for Pre-Peeled Potatoes

Treatment of pre-peeled potatoes with heated ascorbic acid (AA)/citric acid (CA) solution to extend shelf-life was investigated. Potatoes were abrasion or high pressure steam peeled, heated for 5–20 min in 1% AA + 2% CA at 45–55°C cooled, and then dipped for 5 min in browning inhibitor (BI) solution containing 4% AA +1% CA +1% sodium acid pyrophosphate. Combined treatment inhibited potato discoloration for 14 days at 4°C compared to 3–6 days with BI treatment alone. Raw material and treatment conditions were selected to minimize graying and textural abnormalities encountered with some treatments. Treatment with heated AA/CA may be an alternative to use of sulfites to control browning in pre-peeled potatoes.     

挤压重组紫薯米工艺优化 及其抗氧化活性研究

以籼米为主要原料,并添加紫薯粉制备挤压重组紫薯米。主要选取紫薯粉添加量、挤压温度、物料水分含量3个试验因素,以花色苷含量、质构品质和感官评分作为综合指标,进行单因素及响应面优化试验。获得最佳工艺参数为:紫薯粉添加量为10%、挤压温度为80 ℃、水分含量为26%。该工艺条件下获得的挤压重组紫薯米呈现亮紫色,且综合得分最高为71.08±0.79分。体外抗氧化活性试验结果表明,挤压重组紫薯米对DPPH和ABTS的清除率分别为86.71%、87.55%,显示其良好的抗氧化特性。     

几种物料挤压加工过程中的丙烯酰胺形成规律研究

研究了玉米粉、小麦粉、马铃薯粉、小米粉、豌豆粉等几种谷物与杂豆粉经过挤压加工后的丙烯酰胺含量,结果表明马铃薯-小麦混合粉挤出物中丙烯酰胺的含量最高。并以马铃薯-小麦混合粉为基础原料,研究了添加大豆脱脂蛋白、淀粉、蔗糖等对挤压加工过程中丙烯酰胺形成的影响。结果表明大豆脱脂蛋白、淀粉、蔗糖等组分对马铃薯-小麦混合粉挤出物的丙烯酰胺含量均有显著影响(p<0.05)。其中,添加大豆脱脂蛋白8%、淀粉5%、蔗糖12%时,挤压产品中丙烯酰胺含量均达最大值。     

Effects of replacing soybean meal with raw or extruded blends containing faba bean or lupin seeds on nitrogen metabolism and performance of dairy cows

The objective was to test the effects of replacing soybean meal in dairy cow diets with either raw or extruded faba bean:linseed or lupin:linseed blends on intake, milk yield and composition, N partitioning, and ruminal and plasma parameters. Our main hypotheses were that N from extruded blends was less degradable in the rumen than N from raw seeds, and that a higher extrusion temperature favored ruminal protection of proteins and milk protein yield, and lowered urinary N excretion. Eight Holstein cows fitted with ruminal cannulas were used in two 4 × 4 Latin square design experiments conducted in parallel. In both experiments, cows were fed diets with a crude protein content of 14.6%, containing 60% of forage (dry matter basis). Treatments differed by the composition of the concentrates: control in both experiments was based on soybean meal, and experimental treatments were based on proteaginous:linseed (90:10%) blends consisting of faba bean blends (first experiment) or lupin blends (second experiment) presented either raw, extruded at 140°C, or extruded at 160°C. Intake, milk yield and composition, ruminal pH, volatile fatty acids and ammonia kinetics, digestibility, N partitioning, Maillard compounds in feed and feces, plasma AA, and ¹⁵N natural enrichment were measured. Data were analyzed using ANOVA according to the MIXED procedure of SAS (version 9.4, SAS Institute Inc., Cary, NC). Ammonia content in ruminal fluid did not significantly change when soybean meal was replaced by either raw or extruded faba bean, but tended to be higher with lupin. Milk yield was increased by 2.6 kg with faba bean blend extruded at 140°C compared with faba bean blend extruded at 160°C. Milk fat and milk protein concentrations were decreased by 3.1 and 2.3 g/kg, respectively, with lupin blends compared with soybean meal. Nitrogen partitioning between milk, feces, and urine did not change. Nitrogen apparent digestibility decreased by 3 g/100 g of N between faba bean blend extruded at low and at high temperatures. The content of Maillard compounds in feces was higher with blends extruded at 160°C than with raw or extruded at 140°C blends within both experiments. Total plasma AA tended to be higher with extruded blends than with raw in the faba bean experiment. Both extrusion temperatures appeared to protect dietary proteins from ruminal degradability, but proteins seemed to be overprotected at 160°C.     

Effect of formulation and processing parameters on acrylamide formation: A case study on extrusion of blends of potato flour and semolina

Acrylamide formation in extruded snacks prepared using blends of potato flour:semolina in ratios ranging from 30:70 to 70:30 showed maximum acrylamide formation in the 70:30 blend. The extrusion was carried out at a screw speed of 120 rpm, temperature of 170 °C and moisture content of 18%. Further, the influence of extrusion processing parameters on the acrylamide formation in extruded snacks prepared from a 70:30 blend of potato flour:semolina was investigated using response surface methodology (RSM). The feed moisture was varied from 12.6% to 19.4%, die temperature from 163 to 197 °C and screw speed from 106 to 173 rpm. The extrudates so obtained showed acrylamide content ranging from 704 to 1560 μg/kg. The effect of different additives such as citric acid, calcium salts, amino acids, vitamins and their combinations on the mitigation of acrylamide formation showed calcium chloride at 50 μmol/g flour blend to reduce acrylamide formation by 65% without altering the sensory properties of the extrudates.