Controlling rheology and structure of sweet potato starch noodles with high broccoli powder content by hydrocolloids

Incorporating high volume fractions of broccoli powder in starch noodle dough has a major effect on its shear modulus, as a result of significant swelling of the broccoli particles. Several hydrocolloids with distinct water binding capacity (locust bean gum (LBG), guar gum, konjac glucomannan (KG), hydroxypropyl methylcellulose (HPMC) and xanthan gum), were added to systems with 4 and 20% (v/v dry based) broccoli particles, and the effect of this addition on dough rheology, mechanical properties and structure of cooked noodles was investigated. Hydrocolloids with low (LBG and guar gum) and intermediate (KG) water binding capacity had no significant effect on shear rheology of the dough. Adding hydrocolloids with high water binding capacity (HPMC and xanthan gum) decreased the shear modulus of dough with 20% broccoli particles significantly. CLSM analysis of cooked noodles showed that in samples containing xanthan gum there was also an inhibition of swelling of starch granules. Strength and stiffness of cooked noodles with 20% broccoli particles were higher for samples containing xanthan gum, than samples without xanthan gum. The cooking loss and swelling index of samples with added hydrocolloids were slightly lower than samples without hydrocolloids. Our results showed that hydrocolloids with high water binding capacity can be used to control the degree of swelling of vegetable particles and starch granules in starch noodle products, and thereby control both dough rheology and textural properties of the cooked noodles.     

Separation and characterization of food macromolecules using field-flow fractionation: A review

Recent years have seen an increasing interest in asymmetrical flow field-flow fractionation (AF4) as a method for the fractionation and characterization of macromolecules and colloidal particles. In this paper utilization of AF4 in food applications is reviewed. Instrumental considerations are discussed as well as which properties can be assessed by AF4 and adequate detection systems. Furthermore, published literature on analysis of food macromolecules with AF4 is critically reviewed.     

Stabilisation mechanism of various inulins and hydrocolloids: Milk–sour cherry juice mixture

Milk–fruit juice mixtures, such as the mainly acidic nutraceutical soft drinks, usually suffer from phase separation due to aggregation of caseins at low pH. In this study, short‐chain inulin (SCI), native inulin (NI), long‐chain inulin (LCI) and a combination of long‐ and short‐chain inulins (LCI:SCI) (MIX) in different ratios (20:80, 50:50 and 80:20) were added (up to 10% w/v) to a milk–sour cherry juice mixture and their stabilisation mechanisms investigated using rheological, microstructural and zeta potential observations. In addition, gum tragacanth (GT) and Persian gum (PG) as adsorbing and guar gum (GG) as nonadsorbing hydrocolloids were combined with inulin to enhance their stabilising properties. Finally, sensory analyses were carried out on the stabilised samples. According to our findings, LCI fully stabilised the mixture (8% w/v), while LCI: SCI and NI only reduced phase separation at very high concentrations, and SCI had no significant effect on the stabilisation. Moreover, no inulin aggregates and rheological changes were observed with SCI. However, LCI, LCI: SCI and NI formed inulin aggregates and the mixtures became even more viscous and thixotropic (LCI > LCI: SCL > NI). Based on these observations, it can be concluded that chain length and concentration are two important factors that affect the functionality of inulin. On the other hand, the combination of inulin with GT and PG did not have any pertinent effect on the stabilisation. However, the mixture of inulin and GG could stabilise the mixtures at certain ratios and concentrations. Furthermore, in mixtures containing GG and SCI, GG played the main role in the stabilisation by increasing the viscosity and forming gel network.     

Functionalization of hydrocolloids: principal component analysis applied to the study of correlations between parameters describing the consistency of hydrogels

This work was part of a pure research project on the functionalization of three families of hydrocolloids: cellulose derivatives, carrageenates, and alginates. Principal component analysis (PCA), a powerful statistical method, was used to demonstrate the relations existing among these different parameters that describe the consistency of hydrogels and their spreadability. This approach therefore provides a basis for modeling hydrogel consistency. PCA also afforded a classification of hydrogels that demonstrated the remarkable adhesiveness of very stiff gels based on cellulose derivatives and sodium or potassium alginates. The corresponding semifluid gels and all the gels based on carrageenates and mixed sodium-calcium alginates, whatever their spreadability, were found to be very poorly adhesive. Generalized to all the many colloids currently marketed, this approach can be used to set up a databank for the formulation of mucoadhesive excipients.     

糖和亲水胶体对葛根淀粉流变学特性影响的研究

糖和亲水胶体对葛根淀粉流变学特性影响的研究结果表明，随糖和亲水胶体浓度的增加，葛根淀粉溶液的粘度逐渐增加，并且有协同增粘效应。在糖和亲水胶体浓度低时，随糖和亲水胶体浓度增加，葛根淀粉的凝胶强度和剪切强度也逐渐增加，而当糖和亲水胶体浓度进一步增加时，其凝胶强度和剪切强度反而减少。     

Study of oil uptake and some quality attributes of potato chips affected by hydrocolloids

The use of coating agents is one effective way to reduce oil absorption in fried products. Reducing the fat content of fried foods by application of coatings is an alternative solution to comply with both health concerns and consumer preferences. The aim of this study was to analyze the effect of hydrocolloids as coating agent on the quantity of oil uptake and on sensory attributes of potato chips. The effect of the coating composition showed that the minimum fat content was related to 1% carboxymethyl cellulose (CMC), 0.5% xanthan, 0.3% guar and 1% xanthan with 21.2, 21.7, 22.4 and 24.8%, respectively, and the highest of fat content was related to blank sample (non-coated), 2% tragacanth, 0.5% guar gum with 49.4, 41.7 and 33.2% of oil content, respectively (p <0.05). The most effective coating agent reduced the oil uptake by 57.03, 55.94, 54.67 and 49.71%, respectively (p <0.05). Sensory evaluation showed that the best color was related to 1% CMC, 0.3% guar and 2% tragacanth, and with respect to flavor evaluation the best flavor was observed in tragacanth 2%, CMC 0.5% and CMC 0.1%, and the best texture referred to tragacanth 2%, CMC 0.5% and CMC 1%. In sensory evaluation, all coated chips got high scores compared with blank (non-coated chips) samples (p <0.05).     

In vitro starch bioavailability of corn tortillas with hydrocolloids

Tortillas were prepared using commercial hydrocolloids, stored for 7 and 14 days and their available, resistant and retrograded resistant starches, were evaluated alongside their in vitro starch digestibility. Available starch (AS) decreased with storage time and tortillas with hydrocolloids had lower values than the control sample. Tortillas elaborated with TC-20 gum did not present substantial differences in AS. Control tortilla had resistant starch (RS) content that increased with storage time but, in general, tortillas with hydrocolloids did not show any change in RS values with storage time, except tortillas with TC-1 gum that presented a slight increase after 7 storage days. Approximately 50% of RS is due to the retrogradation phenomenon as it was shown by the amount of retrograded resistant starch (RRS). Tortillas with added hydrocolloids had lower hydrolysis percentage and the hydrolysis was slower than in the control. In general, tortillas prepared with hydrocolloids had a lower tendency for retrogradation than control tortillas; it is important to consider this to obtain tortillas with better texture and lower RS content.     

Stabilization of Water Droplets in an Oily Matrix Exclusively by Gel Formation

As droplets in emulsions are thermodynamically unstable, surfactants are required for their stabilization. However, these additives often are unwanted due to legal restrictions and possible health threats. Gelling of the aqueous phase poses one promising alternative. Only droplet‐forming processes like microfluidic devices are known to successfully work so far for stabilization by gelling. As these processes are hard to scale‐up and tend to foul, a technical alternative based on commonly used high‐pressure homogenization is investigated. A nozzle was adapted by adding a micromixer directly behind the orifice outlet. This allowed gelling and stabilizing the droplets by feeding a cold oil stream immediately after droplet breakup. Up to 40 wt‐% droplets with Sauter mean diameters down to the micrometer range could be successfully stabilized.     

Chemical,physico-chemical and cytotoxicity characterisation of xyloglucan from Guibourtia hymenifolia (Moric.) J. Leonard seeds

A water-soluble polysaccharide was obtained from Guibourtia hymenifolia seeds in a 54.2% yield (w/w). The Glc:Xyl:Gal molar ratio was 3.3:2.3:1. The methylation results and 1D/2D NMR spectra indicated the presence of xyloglucan (XG), the intrinsic viscosity of which was 665 mL/g. The molar mass (M_w), radius of gyration (R_g), hydrodynamic radius (R_h), and ρ (R_g/R_h) of XG were 8.43 × 10⁵ g/mol, 97 nm, 61 nm, and 1.59, respectively, indicating a random coil and flexible conformation that was subsequently confirmed by the Mark–Houwink constant α (0.70). Atomic force microscopy analysis of XG adsorbed on silicon revealed that the chains are an average of 1.25-nm high, 28.9-nm wide and 131-nm long. Furthermore, a cytotoxicity assay indicated a high CC₅₀ value (>3.3 mg/mL). These results suggest that this biopolymer has potential applications in different food technologies and biotechnological processes.