EFFECTS OF GELLAN GUM, CITRIC ACID AND SWEETENER ON THE TEXTURE OF LEMON JELLY

Effects of various ingredients on the texture of lemon jellies prepared from gellan gum, citric acid and sweetener were investigated by rheological measurement and sensory evaluation. The data were analyzed by use of the modification of Scheffé's mixture experiment method in converse triangle experiment area. The contours of the response surface were drawn using the best model whose terms were searched by AIC statistic, and the approximate model was calculated to consider the contours. "Hardness" estimated by both methods was large in jellies with high content of gellan gum and low content of citric acid. The content of citric acid significantly influenced "smoothness" estimated by a subjective method. The influence of citric acid varied with the content of gellan gum. The correlation coefficients of evaluation between "hardness" and "lemon flavor" or "sourness" were negative.     

EFFECTS OF CONCHING TIME AND INGREDIENTS ON PREFERENCE OF MILK CHOCOLATE

The objective of this study is to determine how the conching time and the quantity of sucrose, lecithin, cocoa butter and whole milk powder affect consumer preference for milk chocolate. Untrained panelists performed a sensory study consisting of acceptability, preference and attribute intensity. Longer conching time produced significantly smoother chocolate with smaller particle size. The longest conche times had the smallest particle size and were the most mouthcoating. There was no change in flavor with conching. The longer conche times were preferred. Panelists preferred higher sucrose levels, and increasing sucrose decreased bitterness and increased chocolate flavor. Increasing lecithin increased smoothness, but less lecithin was preferred, possibly due to off-flavors at high levels of lecithin. Increasing cocoa butter yielded softer chocolate but did not affect bitterness. Panelists preferred 10% over higher levels of cocoa butter. More milk powder produced smoother chocolate with more caramel flavor and was preferred.

PRACTICAL APPLICATIONS

The perceived quality of milk chocolate is affected by conching time, sucrose, lecithin, cocoa butter and whole milk powder. Texture was affected the most by conching, milk powder, lecithin and cocoa butter. Flavor was affected the most by milk powder and sugar. The only variable that did not affect acceptability and preference of milk chocolate was time for underconched samples. While this study did not determine the optimum conditions for milk chocolate, the most preferred and/or acceptable samples were conched for at least 12 h, had 35 to 50% sucrose, 0–0.5% lecithin, 5–10% cocoa butter and 13–30% milk powder.     

冷冻面团的组分配比对其拉伸性能的影响

实验借助英国CNSFARNELL公司的QTSTextureAnalyser质构分析仪对影响冷面团稳定性的若干因素进行了深入研究。这些影响因素包括:冷冻面团中水分、盐、糖、单甘酯、SSL、磷酸二氢钙的添加量。根据所得到的图表和数据,得出结论:制作冷冻面团时各种原料和添加剂的添加量分虽为:水62%、食盐2%、糖15%、单甘酯0.3%、SSL0.3%、磷酸二氢钙0.3%时面团的拉伸性最佳。     

EFFECTS OF COTTAGE CHEESE WHEY ON THE PROPERTIES OF ICE MILK1

Liquid cottage cheese whey was used in the production of slightly acidic ice milk mixes at levels of 0, 16, 31, 46, and 61%. Because of precipitation problems, whey levels of 46 and 61% could not be used. Consistency index (K) of the ice milk mix was not significantly (p > 0.05) influenced by increasing the cottage cheese whey level from 0 to 31.0%, and all ice milk mixes evaluated exhibited pseudoplastic behavior (flow behavior indices or n value less than unity). Whey at an intermediate level (16%) resulted in slightly higher overrun compared with ice milk at 0 or 31% whey. Further, sensory ratings (flavor, texture, sourness) for ice milk with 16% whey were not different (p > 0.05) from those of control ice milk. While increasing the level of whey to 31% appeared to slightly reduce sensory acceptance of the ice milk, this apparent difference was not significant (p > 0.05). Overall, 46.0% of the panelists preferred the ice milk without whey compared with 32.5% for 16.0% whey and 21.5% for 31% whey formulation.     

EFFECTS OF EMULSIFIERS ON DOUGH RHEOLOGICAL PROPERTIES AND THE TEXTURE OF EXTRUDED NOODLES

The effects of six emulsifiers on the rheological properties of wheat flour doughs were evaluated using capillary and oscillatory rheometers. Sodium stearoyl 2-lactylate (SSL) and sucrose fatty acid ester 160 (SFAE 160) significantly increased the apparent viscosities (η), storage moduli (G") and loss modulus (G") of the doughs. The η, G' and G" increased with the concentrations of SSL from 0.5 to 1.5%. Lecithin, SFAE 110 and 20W (low HLB values) had the opposite effects. Extruded noodle with SSL had the highest tensile strength and cutting force among all treatments. Therefore, SSL could be used to produce the extruded noodles with higher elasticity. Lecithin, MG, SPAE 110 and 20W decreased the strength of the extruded noodles. There was a positive correlation between viscosity and shear modulus of the doughs and the strength of extruded noodles. Values of HLB emulsifiers used in this study were positively correlated with G' and η*.     

磷酸盐对西式蒸煮火腿质构影响研究

研究了不同添加量的磷酸三钠、六偏磷酸钠和焦磷酸钠3种磷酸盐对西式蒸煮火腿TPA特性（硬度、弹性、咀嚼性、凝聚性、回复性）的影响变化规律：随着磷酸盐添加量的增加，TPA特性（凝聚性除外）优化。3种磷酸盐对西式火腿质构影响的大小顺序：焦磷酸钠〉磷酸三钠〉六偏磷酸钠。通过感官评定与机械测试TPA特性之间的相关分析，结果表明感官评定和TPA特性间有较好的相关性。     

EFFECT OF VARIOUS DRYING METHODS ON TEXTURE AND COLOR OF TOMATO HALVES

Tomatoes were pretreated with osmotic solutions (NaCl and sucrose) at different concentrations and then dried using hot air (75C, 1.5 m/s), a vacuum (55C, 75 kPa) or hot-air drying followed by microwave treatment (400 W, 10 s). The effects of pretreatment and drying method on the drying kinetics were examined. A puncture test and scanning electron microscopy were used to analyze the effects of these processes on texture and microstructure. Hunter values ( L, a, b ) were used to measure color. Measurements showed that two osmotic solutions, S₃ (40% sucrose, 5% NaCl) and S₄ (40% sucrose, 10% NaCl), performed better, reducing drying times and having a positive effect on microstructure, but an adverse effect on hardness. Apart from the type of process, dehydration reduced firmness and collapsed the structure of tomato halves. The subsequent microwave treatment then caused further damage, especially on the surface of the dried samples, but enhanced their color when combined with appropriate osmotic treatment.

PRACTICAL APPLICATIONS

This study shows that the color and structural changes of tomato during drying can be reduced using appropriate procedure. This may find application in the production of dried tomato with better appearance and lower drying cost.     

NUTRITION OF THE COW AND ITS EFFECTS ON MILK QUANTITY AND QUALITY

The relationships between diet, metabolism within the rumen and milk secretion are considered and the bases of the effects of nutrition on milk quantity and quality are established. Practical situations under which such effects occur are reviewed, and emphasis is given to other factors which influence their quantitative importance.     

EFFECTS OF VARIOUS FRESH MEAT STORAGE METHODS ON THE COLOR OF COOKED GROUND PORK

The effects of microbial growth in raw materials on cooked pork color were investigated. In two trials with sow meat held aerobically at 2C for 3 weeks, microbial load reached spoilage levels (10⁷ cfu/g), pH increased to 6.46, and samples cooked to 71C had red exudate, shown by absorption spectroscopy to contain myoglobin and cytochrome c. Samples cooked to 82C also received high panel ratings for red color, due to red, flocculent precipitate in the exudate, but undenatured myoglobin levels were low. In sow meat held frozen or vacuum-packaged at 2C, pH after 3 weeks was 6.03 and 6.18, and plate counts were 10⁴ and 10⁷, respectively, but exudates after cooking were much less red. In five trials with fresh pork legs, total plate counts also reached 10⁷ cfu/g by 3 weeks storage, and pH increased to 6.37, but cooked samples were not red. Higher myoglobin levels in sow meat probably accounted for the red color and level of undenatured myoglobin remaining after cooking of high pH, spoiled samples.     

EFFECT OF MANGO PULP AND SOYMILK FORTIFICATION ON THE TEXTURE PROFILE OF SET YOGHURT MADE FROM BUFFALO MILK

The effect of the fat content in buffalo milk and proportions of buffalo milk, soymilk and mango pulp on textural characteristics of mango soy fortified yoghurt (MSFY) is reported. The TA-XT2 Texture Analyzer was used to measure the textural characteristics of MSFY prepared from blends containing varying proportions of buffalo milk (varying fat content), soymilk (8.2% total solids) and mango pulp (18% total solids). Texture profile data were used to develop regression models for dependent variables—hardness (HD), cohesiveness (CO), adhesiveness (AD), springiness (SP) and gumminess (GU), which were used to optimize the blend formula. The optimized values are 2.95% fat content in buffalo milk, 14.7% soymilk and 7.2% mango pulp in the blend for obtaining MSFY having textural characteristics similar to those of yoghurt having 6% fat. The MSFY prepared using optimized blend had HD (108 - 112 g), CO (0.41 - 0.42), AD (- 70.3 to - 72.9 g.s), SP (0.93 - 0.96) and GU (45.05 - 46.38 g).     

NUMERICAL MODELING AND SIMULATION ON THE SWALLOWING OF JELLY

Studies of the swallowing process are especially important for the development of care foods for dysphagia. However, the effectiveness of experiments on human subjects is somewhat limited due to instrument resolution, stress to the subjects and the risk of aspiration. These problems may be resolved if numerical simulation of swallowing can be used as an alternative investigative tool. On this basis, a numerical model is proposed to simulate the swallowing of a simple jelly bolus. The structure of the pharynx was modeled using a finite element method, and the swallowing movements were defined by pharynx posterior wall shift, laryngeal elevation and epiglottis retroflexion. The rheological characteristics of the jelly were investigated using an oscillatory rheometer and a compression test. A Maxwell three-element model was applied to the rheological model of the jelly. The model constants were obtained from compression tests because the mode of deformation and the stress level of the compression tests were similar to those of the swallowed jelly. The frictional relationship between the organs and the jelly was estimated experimentally from some frictional measurements between the jelly and a wet sloping surface. The results of the simulations for the soft and hard jellies showed different patterns of swallowing that depended on their hardness, and the soft jelly produced faster swallowing because of its flexibility.

PRACTICAL APPLICATIONS

The object of this study is to develop a numerical simulation model of swallowing. Numerical modeling is suitable for the quantitative analysis of the swallowing process and may also be expected to enable a systematic study of care foods that are safe and offer some degree of comfort to patients suffering from swallowing disorders. The computer simulation can be used for evaluation without dangerous risks to the patient.