PHYSICAL,CHEMICAL AND SENSORY PROPERTIES OF SUGAR‐FREE JELLY*

The increase in diabetes and obesity has increased the demand for sugar‐free/low‐calorie products. Three jelly formulations were prepared using sucralose, low‐methoxyl pectin and maltodextrin with either xanthan gum or locust bean gum (LBG) used singly or in combination and stored at 4C or 43C for shelf life evaluation. Jelly treatments were evaluated for chemical, physical and sensory properties. The combination of xanthan gum and LBG significantly reduced syneresis compared with either gum used singly. The combination of xanthan gum and LBG resulted in significantly higher firmness and springiness values than using xanthan gum or LBG alone. The overall acceptability, aroma, taste, texture, spreadability and sensory attributes for no sugar‐added grape jelly averaged 5.8–6.4 in a 9‐point hedonic scale consumer acceptance study.     

Sensory quality of low-sugar orange gels with gellan, xanthan and locust bean gums

Effects of reducing the sucrose content (from 55 to 30 ^°Brix in the final product) and of the use of gellan gum or a mixture of gellan, xanthan and locust bean gums (3:1:1) on the mechanical characteristics (maximum rupture force and deformation at rupture) of orange gels prepared with 15% w/w fruit pulp, sucrose and different amounts of hydrocolloids (0.25, 0.4, 0.55 and 0.7% w/w) were studied by uniaxial compression. The concentration of aspartame needed to compensate for sweetness loss was determined by a paired-comparison constant-stimulus method. Sensory characteristics (texture, appearance and flavour) of low-sugar orange gels (30 ^°Brix) with 0.5% w/w aspartame and different amounts (0.55 and 0.7% w/w) of gellan or the mixture of gums were analysed by the free choice profile method in comparison with the high-sucrose reference material (55 ^°Brix and 0.4% w/w gellan). Use of the mixture of gums permitted the obtention of low-sugar orange gels showing mechanical characteristics similar to those of the reference gel, though some differences in texture were perceived. The low-sugar gels were slightly lighter in colour and slightly more bitter and refreshing than the reference sample. Received: 29 November 1995/Revised version: 13 May 1996     

The texture of low calorie grape juice jelly

 In this work the production of grape juice jellies with a low methoxyl pectin was studied. Availability of this kind of jelly will increase the range of dietetic products and is a promising alternative use for grapes surplus to the needs of the enological industry. The formulation of the jellies was optimized by response surface methodology (RSM), using as independent variables total sugar content (20 – 50°Brix), low methoxyl pectin content (0.5 – 1.5%) and processing temperature (55 – 90°C) at five levels. The dependent variable was the overall balance (B), a response obtained from sensory analysis. B was chosen from a series of sensory attributes evaluated by a test panel and the data treated by principal component analysis (PCA). The resulting polynomial equation (R ² = 0.92) showed the maximum value for B to occur for a jelly produced with 38°Brix of total sugar, 1.2% of low methoxyl pectin and a processing temperature of 69°C. The sensory-optimized jelly was objectively characterized for texture and dynamic rheological behaviour. Received: 2 October 1996 / Revised version: 7 January 1997     

红枣银耳复合果冻的研制

为了研制品质优良、营养丰富的果冻,以红枣和银耳为原料进行复合果冻的研制,研究不同凝胶剂的凝胶性能和复配胶的最佳比例,并对复合果冻的配方和制作工艺进行优化。实验结果:复配胶的最佳配比为魔芋胶∶黄原胶∶卡拉胶∶琼脂=2∶1∶1∶1,果冻的最佳配方为:复合果汁(红枣汁∶银耳汁=2∶1)20%,复配胶1.5%,白砂糖12%,柠檬酸0.1%。最优水平组合A2B3C2D1的感官评分为90分。     

Sweetening power of aspartame in hydrocolloids gels: Influence of texture

Equivalent sweetness of aspartame relative to two sucrose concentrations (10% and 20% w/w) were determined in water and in hydrocolloids gels. The influence of the texture of three hydrocolloids gelled systems—gellan gum, κ-carrageenan, and κ-carrageenan/locust bean gum (LBG)—at two gums concentrations (0.3% and 1.2% w/w) on the equivalent sweetness of aspartame were then studied. For the three gelled systems, the increase in hydrocolloid concentration produced a significant increase in the true rupture stress and in the deformability modulus values. For both κ-carrageenan and mixed gels the true rupture strain values increased when increasing hydrocolloid concentration while for gellan gels, decreased. For the same hydrocolloid concentrations the κ-carrageenan/LBG gels showed the largest strain at rupture and gellan gels the smallest (most brittle). For both soft (0.3% gum) and hard (1.2% gum) gellan gels and κ-carrageenan gels, the concentrations of aspartame needed to deliver a sweetness intensity equivalent to that of gels with 10% sucrose (0.079–0.087% w/w) were similar to those obtained for aqueous solutions (0.084% w/v). For hard κ-carrageenan/LBG gels the corresponding concentration of aspartame was slightly lower. For all gelled systems the concentrations of aspartame needed to deliver a sweetness intensity equivalent to that of gels with 20% sucrose were higher for soft gels than for hard gels.     

Saltiness perception related to salt release of surimi emulsified sausages: modulation in texture and microstructure by polysaccharides

The effect of κ-carrageenan (CG), high acyl gellan (HAG), xanthan gum (XG) and locust bean gum (LBG) on the salt release and saltiness perception of surimi emulsified sausages was investigated. CG, LBG and XG significantly reduced the fracture strain to 62.62%, 58.56% and 58.23%, causing the formation of disintegrating gels. Microstructure observation showed that sausages with CG or LBG had porous structure, but the former formed an interpenetrating network and promoted hydrophobic interactions and the formation of disulphide bonds, while the latter was physically filled in the protein network. The maximum salt release was observed in the sausage with CG due to rapid salt diffusion from porous and interpenetrating network structure. Sensory analysis further proved that the saltiness perception of sausages was enhanced by CG. The present work provided an approach for salt reduction in sausages by facilitating salt release achieved by modulating the texture attributes and microstructure using polysaccharides.     

Rheological behaviors of hydroxypropylated sweet potato starches influenced by guar,locust bean,and xanthan gums

This study examined the steady flow and dynamic rheological behaviors of hydroxypropylated sweet potato starch (HPSPS) pastes mixed with guar gum (GG), locust bean gum (LBG), and xanthan gum (XG) at different concentrations (0, 0.3, and 0.6%). The HPSPS–gum mixtures had higher shear‐thinning fluid characteristics than the control (0% gum) at 25°C. The addition of the gums resulted in an increase in the consistency index (K) and apparent viscosity (η_a,100). The dynamic moduli (G′, G″) and complex viscosity (η*) values of the HPSPS–gum mixtures were higher than those of the control, and they increased with an increase in gum concentration. In particular, the presence of XG at 0.6% in the HPSPS–gum mixture systems gave rise to the greatest viscoelastic properties among the gums examined at different concentrations. The tan δ (ratio of G″/G′) values (0.35–0.57) of the HPSPS–GG and HPSPS–XG mixtures were much lower than those of the control (0.82) and HPSPS–LBG (0.88–1.06), indicating that the elastic properties in the HPSPS–gum mixture systems were strongly affected by the additions of GG and XG. These steady flow and dynamic rheological parameters indicated there were synergistic interactions between the HPSPS and gums. The synergistic effects of the gums and modified starch were hypothesized by considering the molecular incompatibility and molecular interactions between the gums and HPSPS.     

Rheological properties of gluten-free bread formulations

In this study, the rheological properties of rice bread dough containing different gums with or without emulsifiers were determined. In addition, the quality of rice breads (volume, firmness and sensory analysis) was evaluated. Different gums (xanthan gum, guar gum, locust bean gum (LBG), hydroxyl propyl methyl cellulose (HPMC), pectin, xanthan–guar, and xanthan–LBG blend) and emulsifiers (Purawave^™ and DATEM) were used to find the best formulation for gluten-free breads. Rice dough and wheat dough containing no gum and emulsifier were used as control formulations. The rice dough containing different gums with or without emulsifiers at 25 °C showed shear-thinning behavior with a flow behavior index (n) ranging from 0.33–0.68 (except pectin containing samples) and consistency index (K) ranging from 2.75–61.7 Pa sⁿ. The highest elastic (G′) and loss (G″) module were obtained for rice dough samples containing xanthan gum, xanthan–guar and xanthan–LBG blend with DATEM. When Purawave^™ was used as an emulsifier, dough samples had relatively smaller consistency index and viscoelastic moduli values compared to DATEM. The viscoelastic parameters of rice dough were found to be related to bread firmness. Addition of DATEM improved bread quality in terms of specific volume and sensory values.     

Effects of food gums and pre-drying on fat content of fabricated fried chips

Deep-frying contributes to the unique taste and texture of fried products. However, they are low in nutritional value. Food industries actively trying to find ways to reduce the fat content while maintaining organoleptic properties of fried foods. In this work, effects of pre-drying and adding food gums on the moisture and fat contents of chips were evaluated. The chips were pre-dried for 60 and 90 min, and gellan gum, guar gum, methylcellulose and xanthan gum were added at the concentration of 0.25, 0.75, 1 and 2 % w/w. The xanthan gum was the most effective gum for fat reduction. The addition of 0.25 % w/w xanthan gum and at 90 min pre-drying reduced the fat content from 20 % (control) to 15 % w/w. The results also indicated that the reduction of moisture content after frying was not affected by the type of gums but the method of pre-drying.     

Influence of type,concentration and flow behaviour of hydrocolloid solutions on aroma perception

The effects of the addition of two hydrocolloids—locust bean (LBG) and xanthan gums—at two concentrations (0.2 and 0.5%, w/v) on the intensity of the aroma of limonene and of isopentyl acetate solutions was studied using the pairwise ranking test. Previously, the rheological behaviour of the studied gums was analysed, finding that while LBG solutions were slightly pseudoplastic at the lower concentration and more so at the higher one, the xanthan solutions were clearly pseudoplastic at both concentrations. Addition of 0.2% LBG did not alter the limonene aroma intensity perceived, but on adding 0.5% LBG, above the coil overlap concentration (c*), the decrease in aroma intensity was significant. Addition of xanthan gum at any concentration did not modify the limonene aroma intensity perceived by judges, which can be attributed to the low value of c* for solutions of this gum. No difference in isopentyl acetate aroma was found among samples.     

Properties of Algin/Calcium and Salt/Phosphate Structured Beef Rolls with Added Gums

Ten polysaccharide gums at two levels (0.5 and 1.0%) were individually incorporated into algin/calcium (AC) and salt/phosphate (SP) structured beef rolls (<6% fat) prepared with 15 and 30% added water. Cook yield, pH, bind and textural properties were evaluated. Each gum had specific effects on properties of beef rolls. For example, kappa-carrageenan improved (P<0.001) cook yields and maintained or improved bind and texture of raw and cooked samples of both meat binding systems. Cook yields of AC products were improved with gellan gum, while yields of SP products were improved with iotacarrageenan. Other gums (xanthan, guar, pectin, carboxymethyl cellulose) improved water holding (cook yields) but had detrimental effects on product texture.     

Rheological study of xanthan and locust bean gum interaction in dilute solution: Effect of salt

An oscillatory capillary rheometer was used to investigate the effects of NaCl, KCl, and CaCl₂ on visco-elastic properties of xanthan and locust bean gum (LBG) blends in dilute solution. Gums were evaluated for intrinsic viscosity and elastic component. Molecular conformation of the xanthan–LBG complex was assessed by the power-law and Huggins equations. Addition of any of the three salts reduced significantly the intrinsic viscosity and elastic component of the gum blends, with a pronounced effect from divalent ions, compared with monovalent ions. The 60% xanthan–40% LBG blend exhibited the strongest attraction between xanthan and LBG. For the three salts, the attraction weakened when 5-mM salt was added and vanished with the addition of 50-mM salt. The strongest attraction between xanthan and LBG molecules was also evidenced by a positive Huggins miscibility coefficient K_m, and a positive attraction–repulsion coefficient α. With addition of 50 mM of any of the three salts, the coefficient α became negative, suggesting a strong repulsion between the two gums. The power-law coefficient b increased as salt concentration and LBG fraction increased in the blends for the three salts, suggesting a more flexible xanthan–LBG complex dependent on salt concentrations and LBG.     

山药东北茶藨子复合饮料研制

以新鲜山药、东北茶藨子为主要原料,添加白砂糖、黄原胶,制作复合浊汁饮料。试验结果表明,其最佳配方为：山药原浆20%、东北茶藨子原汁15%、白砂糖8%、黄原胶0.08%。最终制得口感润滑、酸甜适口、色泽协调、营养丰富、组织状态稳定的复合饮料。     

Galactomannans in disturbances of structured wax–hydrocolloid-based coatings of citrus fruit (easy-peelers)

Locust bean gum (LBG) or guar gum, both typical viscosity formers, were introduced into traditional wax formulations of two easy-peeler citrus fruit cultivars: Nova and Michal. Their performance was analyzed and compared to inclusion of the non-gelling xanthan gum in a similar formulation. Both galactomannans reduced weight loss of the fruit during respiration in a manner similar to a wax-based coating without gum. As for ethanol and acetaldehyde buildup, the viscosity-forming formulations showed no disadvantage in comparison with a commercial coating. CO₂ accumulation with the xanthan coating was favored. Xanthan- and LBG-wax coatings produced the juice with the best taste quality. Inclusion of galactomannan in the formulation did not change the gloss of the coated easy-peelers, even though xanthan is known to produce better gloss. LBG showed superior performance as an addition to coating relative to guar gum, as did xanthan. Its addition changed the structure of the wax coating to a more chaotic, less ordered structure, making it beneficial in terms of fruit respiration.     

Quality and antioxidant properties of a reduced-sugar pomegranate juice jelly with an aqueous extract of pomegranate peels

In the present study, the production of a reduced-sugar pomegranate juice jelly supplemented with an aqueous extract of pomegranate peel (PE) is described. Influence of different carbohydrate polymers (guar (G), xanthan (X) and tragacanth (T) gums) on rheological properties was studied. Combination GXT presented the most similar rheological behaviour to commercial jelly. Jelly (J) and jelly with PE (JE) were stored at 4 °C over an 8 week period for physical, chemical, antioxidant, microbiological and sensory analysis. J and JE showed similar values for °Brix, colour and Aw, though the pH of JE was lower than J. Thiol and phenolic compounds were higher in JE than in J. Antioxidant activity (radical scavenging activity and autoxidation of linoleic acid) was higher in JE than in J at 0 weeks, and were decreasing with time. Pomegranate juice with additives was generally less accepted than J and JE.     

Influence of pH and added gums on the properties of konjac flour gels

The gel strength and texture of konjac gel and mixed gels of konjac and various gums were measured after gelation at various concentrations of alkali. A selection of different alkaline reagents was used. Regardless of alkali concentration, increasing konjac levels caused a decrease in pH but an increase in hardness and strength of konjac/gellan gum mixed gels. The highest gel strength and hardness were given by mixed konjac/gellan gum gels using sodium carbonate as the gelling medium. Under similar gelling conditions, the addition of gellan gum resulted in the greatest gel hardness. Of the gums examined, a possible synergistic effect on konjac/gellan gum mixed gel texture was observed.     

菊粉花茶果冻制作工艺优化

在结合传统果冻工艺配方的基础之上,通过添加菊粉和食用菊花,研制了一种新型的、具有功能性的菊粉花茶果冻。采用单因素实验和正交实验,确定了影响菊粉花茶果冻品质的主次因素,依次为氯化钾用量>复配胶总量>柠檬酸用量>白砂糖用量。通过感官评定,确定了菊粉花茶果冻的最佳工艺配方。结果表明:复配胶的最佳配比为:菊粉:黄原胶:魔芋粉=3:5:2 (m/m);菊粉花茶果冻配方为:菊花水100 mL,复配胶1.0 g/100 mL、柠檬酸0.06 g/100 mL、氯化钾0.08 g/100 mL、白砂糖4.0 g/100 mL,所制果冻产品具有质地均匀,外观良好和花香风味等特点。     

食用胶对重组牛肉加工特性的影响

将转谷氨酰胺酶和酪蛋白酸钠作为重组牛肉使用的黏合剂,添加量为原料牛肉质量的1.2%。在此基础上,分别添加0.3%(m/m)的卡拉胶、亚麻胶等多种食用胶,通过测定黏结性、色差、解冻损失、蒸煮损失、尺寸变化、剪切力、质构来说明食用胶对重组牛肉加工特性的影响。研究结果表明,亚麻胶和黄原胶都显著降低了重组牛肉的黏结性(P ＜ 0.05),且成片性不好。卡拉胶能增加a* 值,δ- 葡萄糖酸内酯(GDL)和卡拉胶的复合胶却降低了a* 值。添加结冷胶、亚麻胶和黄原胶均降低重组肉的解冻损失和蒸煮损失,而且添加亚麻胶和黄原胶的重组牛肉嫩度最大。     

Effect of Anionic Gums on the Texture of Pickled Frankfurters

The addition of the anionic gums, xanthan and carrageenan, stabilized the texture of frankfurter emulsions against acid deterioration at 37°C in vinegar pickle. The proteins collagen, casein, and gluten, and the gums guar, arabic, and locust bean had no effect. The cationic gum, chitosan, formed an acid-stable gel but the gel would not hold the emulsion. The process of acid deterioration had an initial period of firming of the gel texture. Shear (rupture) and elasticity did not show a corresponding initial increase. Subsequent deteriorative changes were less in the emulsions with xanthan gum than in any of the other emulsions. The gum gel is formed at the expense of the protein-fat structure, probably through a gum-protein interaction.     

Rapid Visco-Analyzer (RVA) Pasting Profiles of Wheat,Corn, Waxy Corn,Tapioca and Amaranth Starches (A. hypochondriacus and A cruentus) in the Presence of Konjac Flour,Gellan, Guar,Xanthan and Locust Bean Gums

The Rapid Visco-Analyzer (RVA) 20min test was used to study the effects of different levels of konjac flour, guar, gellan, xanthan and locust bean gums on starch cooking properties. Wheat, corn, waxy corn, tapioca and A. hypochondriacus and A. cruentus starches were affected to different degrees by different levels of the gums. Peak viscosity increased at the higher gum concentrations, especially with locust bean gum at the 0.4 g level. The increase in viscosity was more pronounced with wheat and corn starches than with waxy corn and tapioca starches which consist mostly of highly branched amylopectin thus preventing close physical association between molecules. Amaranth starches showed much lower viscosity with all the gums than the other starches. Peak viscosity, time to reach the peak and maximum setback viscosity were affected by the gums. The increase in viscosity of starch/hydrocolloid systems is due to the release of amy-lose and low molecular weight amylopectin which promotes the formation of polymer complexes and significantly adds to the viscosity of the system.