Quality of Reduced-Fat Frankfurter Modified by Konjac–Starch Mixed Gels

ABSTRACT:  Konjac–potato starch mixed gels were incorporated into reduced-fat (18%) frankfurters and compared with reduced-fat (18% fat, C18) and high-fat (28% fat, C28) controls for textural, sensory properties, and storage stability. At the same konjac concentration, increasing starch level resulted in lower G' (storage modulus) and G" (loss modulus) of the konjac–potato starch mixtures leading to more elastic-mixed gels. No differences in textural hardness among gel-added treatments were noticed. C28 had the lowest sensory firmness and highest juiciness scores. C18 and gel-added treatments had similar juiciness and firmness scores, and all treatments did not differ in overall acceptability.     

Effects of feed moisture and extruder screw speed and temperature on physical characteristics and antioxidant activity of extruded proso millet (Panicum miliaceum) flour

The objective of this work was to determine the impact of extrusion variables [moisture (17–25%), screw speed (170–250 r.p.m.) and temperature (90–150 °C)] on the physical properties and antioxidant activity of proso millet extrudates. Extrusion variables were adjusted using an inscribed central composite rotatable design. Response variables were bulk density (BD), radial expansion ratio, water absorption index, water solubility index, hardness, colour (L*, a*, b*) and antioxidant activity. Moisture and screw speed were the most influential variables affecting millet extrusion: their linear, quadratic and interaction terms accounted for more than 50% of the variability in all responses except for b*. Expansion was greatest at severe conditions of low moisture and high screw speed. These conditions were also consistent with the highest antioxidant activity. This study demonstrated that high expansion and antioxidant activity can be obtained by extruding proso millet under low moisture and high screw speed conditions.     

Fat reduction in comminuted meat products-effects of beef fat, regular and pre-emulsified canola oil

The effects of fat reduction (25.0%, 17.5%, and 10.0%) and substituting beef fat with canola oil or pre-emulsified canola oil (using soy protein isolate, sodium caseinate or whey protein isolate) on cooking loss, texture and color of comminuted meat products were investigated. Reducing fat from 25 to 10% increased cooking loss and decreased hardness. Canola oil or pre-emulsified treatments showed a positive effect on improving yield and restoring textural parameters. Using sodium caseinate to pre-emulsify the oil resulted in the highest hardness value. Cohesiveness was affected by fat type and level. The color of reduced fat meat batters was darker for all, except the beef fat treatments. Using canola oil or pre-emulsified oil resulted in a significant reduction in redness. The results show that pre-emulsification can offset some of the changes in reduced fat meat products when more water is used to substitute for the fat and that pre-emulsification can also help to produce a more stable meat matrix.     

不同热处理方式对牛肉嫩度和挥发性风味物质的影响

为明确不同热处理方式对牛肉品质特性的影响,分别采用常规卤煮、微波和超声辅助卤煮等方式加工牛肉,对加热过程中（5、15、25、35 min）牛肉样品的水分含量、持水力、剪切力、质构特性、微观结构、挥发性风味及感官品质进行测定与分析。结果表明,经水浴加热5 min（W₅）的牛肉样品中的水分含量最高（62.9%）,而微波加热15 min（M₁₅）样品的持水力高达91.8%,其剪切力、硬度和咀嚼性较低,而弹性值最高（3.94 mJ）。微观结构显示,经微波加热15 min（M₁₅）和超声波辅助加热25 min（U₂₅）的牛肉肌纤维结构较为松散,与质构特性结果对应。经不同热处理方式加工后的牛肉中共检测出98种挥发性风味物质,其中壬醛、桉叶油醇、芳樟醇、丁香酚和茴香脑等阈值较低,为主要呈味物质。主成分分析（PCA）显示,不同热处理方式可显著改变牛肉的特征风味,其中W₅、W₁₅（水浴加热15 min）、M₅（微波加热5 min）、U₅（超声波辅助加热5 min）的主要挥发性风味物质相似,M₁₅、U₁₅（超声波辅助加热15 min）和W₂₅（水浴加热25 min）样品的主要挥发性风味物质相似。进一步结合感官评分,可知微波卤煮15 min后的牛肉品质最佳。     

红高葡萄一次无核化处理技术研究

本文以红高葡萄品种为材料,在不同时期用不同浓度赤霉素(GA3)和吡效隆(CPPU)一次处理,研究其对果实发育的影响.结果表明,各处理都使红高葡萄的无核率提高;GA3和CPPU混合使用此单独使用GA3的效果要好;其中在盛花期使用GA325mg/L+CPPU10mg/L一次处理无核率达100%.综合看来,一次处理的最佳方案为GA325mg/L+CPPU7.5～10mg/L在盛花期至盛花期后4d处理.     

热处理及不同浓度食盐对生鲜面条品质及货架期的影响

本文以复配水分活度调节剂为基本配方,探究热处理及不同浓度的食盐对生鲜面条水分含量、水分活度、水分分布、色泽、蒸煮以及质构、糊化特性的影响。试验结果表明:热处理和添加不同浓度的食盐降低了生鲜面的水分活度,当食盐的添加量为3%时,98 ℃热处理后生鲜面条的水分活度达到最低为0.884。热处理降低了生鲜面条中水分的自由度,增加了生鲜面条中结合水的含量;在不添加食盐的条件下,与未经热处理的样品相比,98 ℃热处理使生鲜面条的亮度从91.07提高至92.93,总色差ΔE从10.04降低为3.06。在88 ℃热处理条件下,随着食盐含量的增加,生鲜面条的硬度、拉断力和拉伸距离先增加后降低,当食盐的添加量为3%时,热处理后生鲜面条的硬度变化与未经热处理的生鲜面条硬度(4471.81 g)没有显著性差异,热处理使生鲜面条糊化特性中的峰值黏度降低,糊化温度升高。此外,热处理和一定浓度的食盐可延长生鲜面条的货架期,在食盐的添加量为2%,98 ℃热处理4 min的条件下制备的生鲜面条于25 ℃储藏其货架期可达96 h。     

Influence of Extrusion-Cooking Parameters on Some Quality Aspects of Precooked Pasta-Like Products

ABSTRACT:  The present article aims to evaluate some quality parameters and texture characteristics of precooked wheat pasta-like products. Using the methods for pasta and instant noodles the tested parameters were water absorption, starch gelatinization degree, cooking losses, and hardness. The texture profile was characterized using Zwick apparatus by cutting test with the head speed of 10 mm/min and expressed as hardness and firmness of hydrated products. SEM pictures were used to illustrate the internal structure of dry and cooked pasta-like products. Dough moisture content and process conditions influenced all tested quality parameters of the pasta-like products processed on a modified single screw extrusion-cooker TS-45 with L : D  = 16: 1. Good organoleptical quality (notes higher than 4 in a 5-point scale) and firm texture were observed for common wheat flour pasta processed at 30% m.c. Hardness and firmness of hydrated products lowered with a longer hydration time in hot water. The firmest texture and low stickiness was observed for products with a highest starch gelatinization degree.     

盐含量对泡辣椒发酵过程中质构劣化及相关理化指标变化的影响

该研究通过考察不同食盐含量下泡辣椒发酵过程中质构劣化与微生物数量、pH、水分存在状态以及总果胶酶活力变化之间的关系,研究食盐含量对泡辣椒质构品质形成的影响机制。结果表明,当食盐含量为4%～6%时,乳酸菌适度产酸,且高渗环境促进辣椒组织中的自由水渗出或转化为不易移动水,导致样品水分活度显著下降。同时,由于果胶酶活性受到显著抑制,细胞结构完整且水分结合能力增强,有助于样品硬度、咀嚼性和脆性的提升。当食盐含量＜4%时,体系中果胶酶活性高,导致样品质构劣化。而食盐含量＞6%时,高渗环境导致泡辣椒组织过度失水坍塌,硬度、咀嚼性和脆性均下降。因此,4%～6%的食盐含量可有效控制泡辣椒质构劣化。     

Texture of Glassy Corn Cakes as a Function of Moisture Content

Glass transition temperatures of yellow and white corn cakes were investigated within the moisture range of 2 to 32% (w/w) using dynamic differential scanning calorimetry. All measurements were conducted at 10°C/min heating rate, 30 sec equilibrium period, and 1°C amplitude. Effects of water plasticization on corn cakes were predicted by the Gordon-Taylor's equation. Moisture sorption isotherms were established using BET and GAB equations. Relationships were found among glass transition temperature, moisture content and cake texture. The loss of crispness of corn cakes occurred within the glassy state. The initial loss of crispness occurred around monolayer moisture content, and the complete loss of crispness occurred at about 9% moisture with the highest hardness.     

Quality and textural behaviour of par-baked and rebaked cake during prolonged storage

The effect of par-baking and refrigerator storage on the quality of cake was investigated. Quality evaluation of rebaked cakes was performed by using physical, chemical and instrumental texture profile analysis. Cakes were par-baked for 15, 20 and 25 min at 175 °C and then they were stored at refrigerator temperature (4 °C) for 30, 60 and 90 days, wrapped with two polyethylene bags. After storage, par-baked cakes were rebaked at 175 °C and were subjected to analysis. Par-baking and intermediate storage time had a significant effect on baking loss, crumb moisture content, colour, symmetry index and textural properties of cake. The increase in the par-baking time led to a decrease in the baking loss and an increase in the moisture content of cake. Specific volume, moisture content, L colour value and symmetry index significantly decreased with increasing intermediate storage time, while baking loss significantly increased. However, regarding the crumb hardness, cohesiveness, springiness, gumminess and chewiness, the results indicated that the best result was obtained when cakes were baked for 15 min at the par-baking stage. Overall, the cakes became firmer, less cohesive and less dry crumb as the intermediate storage time increased, whereas springiness increased.     

The utilisation of grapeseed oil in improving the quality of dry fermented sausages

This study aims to examine the scope of changes in colour, texture and sensory characteristics of fermented sausages by substituting 20% of backfat with grapeseed oil prepared as liquid (GS), encapsulated (EGS) and pre‐emulsified [with soy protein isolate (GSI) and alginate (GSA)], and their stability during 30 days of refrigerated storage. Protein and fat contents, pH and TBA values were not significantly different between products after production and storage. Treatments with added oil had higher weight loss (1.5–2.5%), while moisture content was significantly lowest in GS. Internal product colour evaluation showed the highest values of L*, b* and hue angle in GSI. GSI had the highest hardness and chewiness. Storage affected more surface than internal product colour, hardness was significantly changed only in GSI (lower) and EGS (higher), and increasing of TBA did not lead to significant differences between treatments. The study showed that GSA was the most promising of all treatments investigated.     

Effect of high pressure treatments combined with various levels of κ-carrageenan on cold-set binding in restructured pork

This study investigated the effects of high pressure processing and κ-carrageenan on cold-set binding in restructured pork meat. High pressure (>200 MPa) combined with carrageenan level higher than 1.5% caused increased breaking force and tensile strength ( P  < 0.05). Increasing the pressure level caused a continuous κ-carrageenan network in the junctions between meat particles, as confirmed by scanning electron microscopy imaging. With regard to the water binding properties, all treatments showed moisture content ranging between 74% and 76%. Increases in pressure levels and holding times tended to improve the water-holding capacity (WHC) of restructured pork; however, the κ-carrageenan concentration showed no relation with WHC. Cooking loss decreased significantly ( P  < 0.05) with increases in both pressure level and κ-carrageenan concentration. By increasing pressure levels, both the L ^*- and a ^*-values increased, but the b ^*-value showed no significant difference ( P  > 0.05) among the treatments, with the exception of 100 MPa for 30 min. The addition of κ-carrageenan had no effect on colour ( P  > 0.05). Therefore, the results indicate that pressure above 200 MPa and addition of 1.5% carrageenan has potential use in cold-set meat restructuring.     

A study of the quality characteristics of frozen Korean rice cake by using different thawing methods

The characteristics of frozen rice cakes after thawing them using different methods, such as standing at room temperature (NT), running water (RWT), pan-grill (PT), steam (ST), microwave (MWT), and superheated steam thawing (SHST), were compared. Frozen rice cakes treated by MWT or SHST showed the shortest thawing time of 3 min. The MWT treatment showed the largest thawing loss, while the ST treatment showed the highest moisture content. The ST, RWT, and MWT treatments showed the highest water activity values. The NT treatment exhibited the highest hardness values, whereas the ST treatment showed the lowest values, possibly due to the adverse effects of high temperature on them. Sensory evaluation showed differences in appearance, moistness, and tenderness according to the thawing method, but there was no significant difference in overall acceptability. This study suggests that the qualities of frozen rice cakes varied depending on the different thawing methods.     

植物乳杆菌接种量对低盐风干肠品质特性及风味特征的影响

探究不同接种量105、106、107 CFU/g（LP5、LP6、LP7）的植物乳杆菌对低盐风干肠品质特性及风味特征的影响。以低盐风干肠（食盐质量分数为1.75%）为对照组，在发酵第0、3、6、9天对4 组风干肠的pH值、水分含量、水分活度、剪切力、乳酸菌数和肠杆菌数进行测定；采用电子鼻与气相色谱-质谱技术，对第9天样品的风味特征进行分析。结果表明，随着发酵的进行，各处理组的水分含量和水分活度逐渐降低，剪切力逐渐上升；发酵结束时（第9天），所有处理组中LP6和LP7的水分含量和水分活度较高，LP7的肠杆菌数最低，各处理组的剪切力无显著差异（P＞0.05）。随着植物乳杆菌接种量的增加，低盐风干肠的pH值逐渐下降（除发酵第0天），乳酸菌数逐渐上升（除发酵第6天）。接种植物乳杆菌增加了酸和酯类物质整体含量，不同接种量低盐风干肠挥发性风味差异明显。结合感官评价结果确定接种量106 CFU/g的低盐风干肠的总体可接受性最佳，咸味酸味适中。     

Effect of temperature and initial moisture content on sorption isotherms of banana dried by tunnel drier

Sorption isotherms of intermediate moisture content (IMC) products are essential to predict shelf-life of packaged moisture-sensitive product by modelling moisture uptake during storage and distribution. The effect of temperature and initial moisture content (MC) of IMC banana on the relationship between MC and water activity were investigated. Raw bananas were dried in a tunnel dryer at 2% relative humidity (RH), 70 °C, and a 3.2 ± 0.2 m s^–1 air velocity. Drying procedure was carried out a number of times until various IMC levels were obtained (5%, 14%, 22% and 33% db for banana). Sorption isotherms of bananas were determined at 10, 20, 30 and 40 °C. The initial MC of IMC banana had no significant effect on the relationship between MC and water activity according to statistical analysis. All the sorption curves were found to be Type II. BET, GAB, modified GAB, Oswin, Halsey and modified Freundlich models were fitted to the data and it was found that the best results were obtained with a modified Freundlich equation. A secondary modified Freundlich model was built accounting for the effect of a _w and temperature on the sample MC.     

Application of Glazing for Bread Quality Improvement

Glazing is a surface coating method for enhancement of the quality factors of bakery products. This study was intended to investigate the effect of different bakery glazing groups such as natural, polyols, sugars, and hydrocolloids on Barbari flat bread. Some quality attributes of bread such as moisture content, water activity, specific volume and width/height ratio (0 day) and hardness, crumb, and crust moisture (0–12 days) were evaluated. Results showed that vegetable oil treated samples had the lowest water activity and moisture content. Also, xanthan treatment provided the greatest effect on the specific volume of fresh bread, which enhanced it from 3.94 to 5 cm³/g. Vegetable oil, glycerol, dextrose, liquid glucose, and guar treatments had more significant effect on width/height ratio in comparison to nontreated (unglazed) bread. Evaluation of crumb hardness and moisture during 12 days storage implicated water, egg yolk, starch, and propylene glycol treatments were able to diminish the bread staling and these treated samples had the lowest crumb hardness. Crumb moisture of Barbari bread was affected mostly by water and starch treatments at day 12. Finally, our finding approved that using of glazing as a novel method is an effective technique for improvement of overall quality of flat bread and its application is suggested for large-scale production of other bakery products.     

Optimization of the production of acetylated distarch adipates using the novel software 'MULTIPLEX'

Acetylated, cross-linked and pregelatinized cassava starches were produced in a single-screw extruder with different moisture contents (180, 220 and 260 g kg^–1), reagent (adipic acetic mixed anhydride) concentrations (4, 11 and 18 g kg^–1) and screw speeds (100, 130 and 160 r.p.m.). The acetylation, cross-linking and pregelatinization increased cold viscosity (CV), water absorption index (WAI) and gel hardness, it also reduced gel cohesiveness, paste clarity and retrogradation of the modified-starches compared with control samples (CSs). A novel microcomputer program called MULTIPLEX was developed for the optimization of the process. The optimization process maximized CV, WAI, gel hardness and paste clarity, and minimized gel cohesiveness and retrogradation of the modified-starches. The optimum conditions were moisture of 240 g kg^–1, reagent concentration of 4 g kg^–1 and screw speed of 100 r.p.m. Experimentally determined values for all responses found in products processed under the optimum conditions were very close to the predicted values and this confirmed the validity of predicted models.     

Sensory and physicochemical changes occurring during storage of Galician chorizo in oil

 Changes in the physicochemical and sensory properties of Galician chorizos stored in olive oil, sunflower oil or pork fat were monitored over a 19-week period. The results of analysis of variance showed that the storage medium had a significant effect on some variables. Specifically, moisture content, water activity, acid value and cohesiveness were lowest in chorizos stored in sunflower oil; acid value and pH were highest in chorizos stored in olive oil; external smoky and paprika odours were lowest, and after-taste intensity highest, in chorizos stored in pork fat. Acid value, peroxide index, hardness, colour, external odour intensity, perceived hardness and acid flavour all increased significantly during storage, while pH and water activity declined. In all three storage media, external rancid odour and rancid after-taste were first detected at week 17, when the peroxide index peaked. The overall rating was best for chorizos stored in sunflower oil. Received: 9 September 1997 / Revised version: 24 November 1997     

Sensory and physicochemical changes occurring during storage of Galician chorizo in oil

 Changes in the physicochemical and sensory properties of Galician chorizos stored in olive oil, sunflower oil or pork fat were monitored over a 19-week period. The results of analysis of variance showed that the storage medium had a significant effect on some variables. Specifically, moisture content, water activity, acid value and cohesiveness were lowest in chorizos stored in sunflower oil; acid value and pH were highest in chorizos stored in olive oil; external smoky and paprika odours were lowest, and after-taste intensity highest, in chorizos stored in pork fat. Acid value, peroxide index, hardness, colour, external odour intensity, perceived hardness and acid flavour all increased significantly during storage, while pH and water activity declined. In all three storage media, external rancid odour and rancid after-taste were first detected at week 17, when the peroxide index peaked. The overall rating was best for chorizos stored in sunflower oil. Received: 9 September 1997 / Revised version: 24 November 1997     

Stability and consumer acceptance of long-chain omega-3 fatty acids (eicosapentaenoic acid, 20:5, n-3 and docosahexaenoic acid, 22:6, n-3) in cream-filled sandwich cookies

ABSTRACT:  We formulated a filling for sandwich cookies containing 400 mg of eicosapentaenoic acid, 20:5, n-3 (EPA) + docosahexaenoic acid, 22:6, n-3 (DHA) encapsulated in a matrix of starch and gelatin. Cookies were stored at 2 different temperatures (18 °C and 35 °C) and under 2 different packaging conditions (atmospheric and vacuum packed) for 28 d. At regular intervals, cookies were analyzed for moisture, water activity, and concentrations of EPA, DHA, and dienes. Results showed that there were no significant losses of EPA and DHA during storage under the conditions of study. A maximum loss of 5% was observed after 28 d of storage. The concentration of dienes obtained under different conditions were low (< 25 mmol/kg) as compared to a salmon oil sample with appreciable signs of oxidation (600 mmol/kg). Sensory evaluation of cookies by an untrained panel of healthy consumers and ulcerative colitis patients revealed no aftertaste and high acceptability of the cookies. Our results demonstrated that it is possible to make shelf-stable fortified foods with high levels of long-chain ω3FA.