Improving effect of xanthan and locust bean gums on the freeze-thaw stability of white sauces made with different native starches

The effect of adding xanthan gum and locust bean gum at low concentrations (0.15% w/w) on the freeze/thaw stability of white sauces prepared with native starches from four different sources (corn, waxy corn, potato, and rice) was investigated. Linear viscoelastic properties were taken as structural indicators and these and syneresis as indicators of the freeze/thaw stability of the sauces. The pasting properties of the starch in the sauce system were also studied. Both hydrocolloids reduced the structural changes occurring after thawing, xanthan gum being more effective than locust bean gum. In corn and potato sauces, the most affected by the freeze/thaw cycle, the appearance of syneresis and the increase in viscoelastic functions were significantly reduced by both hydrocolloids. In general, the addition of hydrocolloids affected peak, hot peak and cold peak viscosities and reduced relative total setback. The results regarding the possible effects of hydrocolloid addition to white sauce systems are discussed in molecular terms.     

Influence of corn starch type in the rheological properties of a white sauce after heating and freezing

The freeze/thaw and heating stability of white sauces prepared with two modified waxy corn starches (hydroxypropyl distarch phosphate and acetylated distarch adipate) and two native corn starches (waxy and normal) are compared.     

Microwave heating effect on rheology and microstructure of white sauces

The microstructure and rheological properties of white sauces formulated with different starches were analyzed after being microwave-heated for different times. Significant differences (P < 0.05) in rheological parameters analyzed-storage modulus (G'), loss modulus (G″), and loss tangent (tanδ)-were obtained for sauces made with different starches. Microwave reheating did not affect G' and G″ values until water evaporation became significant. In addition, tanδ values did not change significantly (P < 0.05) even during long reheating times showing that sauce viscoelastic properties did not change after microwave irradiation. However, microstructure assessed by confocal laser scanning microscopy showed changes in fat globule and protein. These microstructural changes did not seem to have a significant effect on rheological measurements since starch and ι-carrageenan are mainly responsible for the viscoelastic behavior of the sauces. Practical Application: The development of products appropriate to microwave heating is constantly rising in food industry. It is necessary to understand the behavior of the ingredients and the final product to microwave heating in order to choose those ingredients which will develop the best performance. Starches are common ingredients in industrial sauces, and rheological and microstructural techniques have shown their usefulness in characterization of starch-based systems.     

Effects of waxy maize and potato starches on the stability and physicochemical properties of model sauces prepared with fresh beef meat

Stability and physicochemical properties of model sauces containing 2.5 wt% fresh beef meat (related to raw material), 30 wt% rapeseed oil and native waxy maize starch (WMS) or potato starch (PS) at concentrations ranged from 0.5 to 4.0 wt% were assessed. Sauces thickened with WMS showed a significantly (P < 0.05) higher stability than respective ones made with PS. All studied systems exhibited non‐Newtonian, pseudoplastic behaviour. The Ostwald–de Waele and Herschel–Bulkley models were used to describe the flow properties of model sauces. In comparison with control sample (prepared without starch), addition of this polysaccharide (WMS or PS) increased consistency index, yield stress and apparent viscosity and decreased flow behaviour index of model sauces. The Arrhenius equation was used to determine the effects of temperature (20–50 °C) on the apparent viscosity. The activation energy values were in ranges 7.66–10.59 kJ mol^?1 and 8.87–11.82 kJ mol^?1 in sauces prepared with WMS and PS, respectively. The instrumentally detected changes in consistency and whiteness of model sauces were found, which may be used as the good predictors of the perceived sensory consistency and whiteness.     

Effects of non-starch hydrocolloids on the physicochemical properties and stability of a commercial béchamel sauce

The aim of this study was to investigate the effects of non-starch hydrocolloids (NSH) on the physicochemical properties and stability of a béchamel sauce. Three different NSH (guar gum, xanthan gum and carboxymethylcellulose) were added at two concentrations (0.10 wt.% and 0.25 wt.%) hereby replacing an equal amount of modified starch. Sauce batches were stored at refrigerated temperatures during four weeks and were rheologically characterized at day 2, 16 and 30 after preparation. The addition of all hydrocolloids caused a marked increase of the consistency index compared to the model system whereas this parameter decreased for all sauces during refrigerated preservation. The yield stress was also increased by the NSH. Furthermore all studied NSH reduced the amount of syneresis, with xanthan gum being the most effective. Besides, sensory tests demonstrated that there were no significant differences in taste and general preference between the hydrocolloid sauces and the model system.     

白芸豆淀粉与小利马豆淀粉理化性质的比较研究

本实验以白芸豆和小利马豆为原料,采用碱法提取淀粉,对白芸豆淀粉和小利马豆淀粉的理化特性进行分析研究。结果表明,白芸豆和小利马豆的淀粉颗粒均呈表面光滑、无棱角及裂痕的特征,且2种淀粉的微晶结构均为A型;2种豆类淀粉的溶解度和膨胀度均随温度的升高而增加。小利马豆淀粉和白芸豆淀粉在冻融稳定性、透明度和成糊特性等方面存在显著差异,小利马豆淀粉的膨胀度、溶解度及淀粉糊的冻融稳定性和透明度更好,而白芸豆淀粉呈现起糊温度、峰值黏度、破损值和回生值较低的成糊特性,易成糊、抗剪切。     

Gelatinization of waxy starches under high pressure as influenced by pH and osmolarity: Gelatinization kinetics, final structure and pasting properties

We investigated the influence of pH and osmolarity on the high-pressure-induced gelatinization of waxy corn and waxy rice starches in salt solutions, and the properties of the resulting gels. Gelatinization kinetics, the gel swelling power of starches, their structure and their rheological properties were studied for starch suspensions treated at 500 MPa. Gelatinization took place mostly in the first 15 min of the pressure treatment and both the gelatinization speed and the maximal level of gelatinized starch decreased with increasing osmolarity. pH had a minor influence on gelatinization kinetics differing from one starch to another. The resulting gels appeared as a mix of a gel and starch granules with a higher proportion of native granules with increasing osmolarity. Gel strength and swelling were positively correlated to their proportion of gelatinized starch. Thus, gels with different structures and gelatinization levels can be obtained under pressure depending on pH and osmolarity.     

Microstructural, physical, and sensory impact of starch, inulin, and soy protein in low-fat gluten and lactose free white sauces

The microstructural, physical, and sensory properties of low-fat sauces made with different starches, soy protein, and inulin as a fat replacer were analyzed. Gluten-free waxy starches-rice and corn-were selected as well as soy protein to obtain sauces suitable for celiac and lactose intolerant consumers. Light microscopy was used to visualize the swollen starch granules dispersed in a protein-amylopectin-inulin phase. Inulin seemed to limit protein network development, which was related with a higher dispersion of starch granules within the sauce matrix. Therefore, the sauces made with inulin had a lower apparent viscosity (η(app) ) values (P < 0.05) in comparison with oil sauces. The sauces made with rice starches also exhibited a lower viscosity (P < 0.05) since these granules did not swell as corn granules do. All the sauces had a remarkable physical stability since there were no syneresis phenomena and color did not change significantly (P < 0.05) after 15 d of refrigeration storage (4 °C). Finally, the sensory test suggests that oil could be substituted by inulin in the preparation of low-fat sauces since no significant differences (P < 0.05) in texture and flavor were found. These results encourage further research to optimize the formulations of these types of alternative white sauces. Practical Application: Nowadays there is a great demand of ready-to-eat products due to new consumptions habits. In this context, it would be interesting to develop low-fat sauces with inulin that could be used in this type of products improving their nutritional profile. The requirement of processed food for specific groups of population, such as celiac and lactose intolerant consumers, makes it necessary to use gluten free starches and soy protein in the formulation of sauces. The characterization of structural, physical and sensory properties is required to understand the product acceptability and its behavior during its shelf life.     

Rheological behaviors,structural properties and freeze–thaw stability of normal and waxy genotypes of barley starch: a comparative study with mung bean,potato, and corn starches

The rheological behaviors, structural properties and freeze-thaw stability of starch isolated from Tetonia barley (Normal genotype, Reg. No. CV-334, PI 646199) and Transit barley (Waxy genotype, Reg. No. CV-348, PI 660128) were investigated, along with other common starch sources for comparison. Transit barley starch showed the highest loss tangents (tan δ) during a frequency sweep test, which suggested a predominance of elastic properties over viscous properties. However, the tan δ of Tetonia barley starch was similar to that of potato starch, which indicated more solidity in comparison to Transit barley starch. Transit barley starch had the highest gelatinization temperature and the lowest gelatinization enthalpy (P < 0.05). Moreover, Tetonia and Transit barley starches displayed weak diffraction peak intensities by X-ray diffraction analysis. Additionally, Transit barley starch showed the lowest % syneresis even when freeze–thawed up to five cycles (P < 0.05). However, Tetonia barley starch had the worst freeze–thaw stability (P < 0.05), which was verified via scanning electron microscopy analysis of freeze–thawed starch gels. The results of present study indicate that barley starch can be practically applied as a functional ingredient in some specialty starchy foods.     

Enrichment of stirred yogurt with soluble dietary fiber from Pachyrhizus erosus L. Urban: Effect on syneresis, microstructure and rheological properties

Yam soluble fiber (YSF) extracted from Pachyrhizus erosus was added (1 g per 100 mL) to a stirred yogurt (SY_YSF). Its syneresis and microstructure properties were evaluated and compared to those of a stirred yogurt (SY_C) without added YSF. The SY_C yogurt exhibited a more compact casein micelle aggregates network than that of the SY_YSF yogurt which was more open, relaxed and covered with fibrous structures attributed to the YSF components. The rheological analysis showed that the SY_YSF yogurt had lower storage modulus (G′) and loss modulus (G″) values in the linear viscoelastic region than the SY_C yogurt, but its flow behavior was characterized by a lower flow index (n), higher consistency index (k), and higher yield stress (τ₀) than the SY_C yogurt. Incorporation of the YSF reduced significantly the syneresis and produced a more acceptable mouthfeel in the SY_YSF yogurt in comparison to the SY_C yogurt, indicating the viability of the process to obtain a commercial product.     

Rheological properties of Lepidium sativum seed extract as a function of concentration, temperature and time

The seeds of Lepidium sativum (Garden Cress) were selected as a new source of hydrocolloid and its chemical composition and molecular parameters were determined. The macromolecular component of the extract had a molecular weight of 540 kDa, and was nearly as rigid as xanthan with regard to chain conformation. The main rheological features were investigated as a function of shear rate, concentration and temperature. The extract exhibited strong shear-thinning behaviour, which was even more pronounced than for xanthan. An increase in concentration or temperature led to an increase in pseudoplasticity. The Arrhenius model was applied to the temperature dependence of viscosity, and the activation energy (E_a) was found to decrease with increasing concentration. The extract solutions showed thixotropic behaviour at all the concentrations and temperatures studied, and the first-order stress decay model with a non-zero equilibrium stress fairly described the time-dependent behaviour. The rheological characteristics found indicated a potential application of the extract as a novel thickener.     

Physico-chemical properties of jackfruit seed starch (Artocarpus heterophyllus) and its application as a thickener and stabilizer in chilli sauce

This study investigates the possible utilization of starch extracted from jackfruit seed waste from the jackfruit frying industry. We first compared the physico-chemical properties of jackfruit seed starch (JFSS) with cornstarch (CS) and potato starch (PS) and then compared JFSS with CS as a thickener and stabilizer in chilli sauce. JFSS had a higher amylose content and its granules were much smaller than CS and PS granules; in addition, JFSS had a higher pasting temperature and final viscosity than CS and PS. JFSS experienced lower breakdown than CS and PS pastes which indicates that JFSS paste is more resistant to thermal and mechanical shear during cooking. The XRD patterns showed JFSS to be Type A starch, similar to corn starch. JFSS is suitable as a thickener and stabilizer in chilli sauce because chilli sauce with JFSS had the lowest serum separation and highest viscosity during storage compared with control chilli sauce and sauce containing CS. In addition, sensory evaluation demonstrated that chilli sauce containing JFSS received the highest score in terms of color, mouth feel, homogeneity and overall quality.     

Partial characterization of white cabbages (Brassica oleracea var. capitata f. alba) from different regions by glucosinolates, bioactive compounds, total antioxidant activities and proteins

Glucosinolates (GLS), antioxidative compounds, total radical scavenging activities (TRSAs) and proteins of white cabbage samples derived from different regions of Europe, collected in the spring and autumn, were studied. Glucobrassicin and sinigrin were the dominating GLS in all analyzed cabbage samples. Depending on origin, these two GLS accounted for ∼30% to ∼70% of the total. The total GLS content ranged from 3.3 to 7.7 μmol/g dw in lyophilized vegetables. Assays based on electron transfer [total phenols by Folin-Ciocalteu reagent (FCR), 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)] radical cation (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH)] were used to compare the TRSAs and the main bioactive compounds in cabbage. Total polyphenols varied from 2.4 to 4.9 GAE/g dw. The TRSAs ranged from 2.7 to 8.2 μmol TE/g dw in ABTS test and from 2.4 to 5.4 μmol TE/g dw in DPPH assay. The maximum amount of polyphenol compounds, antioxidant activity, as well as total GLS content, were recorded in Belgian cabbage harvested in the autumn and the lowest ones were found for Poland 2 cabbage harvested in the spring. In extracted and separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) proteins from cabbage leaves only in samples from England and Belgium some differences in patterns were found in the regions of 60 and 97 kDa. The calculated correlations between antioxidative potency and the abundance of bioactive compounds were highly statistically significant. This suggests that TRSA could serve as a means of standardization of natural mixtures, at least in the case of cabbage, necessary to compare results of biological studies carried out for vegetable derived samples.     

In vitro digestibility of starch in cooked potatoes as affected by guar gum: Microstructural and rheological characteristics

Potatoes from different New Zealand cultivars (Nadine, Moonlight, Red Rascal, Agria) were analysed for starch digestibility in vitro (under simulated gastric and small intestinal conditions). The extent of starch hydrolysis (%) for all the potato cultivars ranged between 85% and 95% at the end of in vitro digestion. Nadine potatoes, which were waxy in texture, showed higher starch hydrolysis (%) whereas these levels did not differ significantly among the other three cultivars. Confocal laser scanning microscopy and scanning electron microscopy were performed on the digests in order to study the microstructural changes occurring during digestion in cooked potatoes. The micrographs clearly showed that starch was quickly hydrolysed by the enzymes present in simulated intestinal fluid (SIF) whereas the cell walls remained intact during simulated digestion process. Addition of guar gum (0.5%) to cooked potatoes reduced their starch hydrolysis (%) by ∼15% during the in vitro digestion. Online viscosity measurements were also performed on the cooked potatoes during simulated small intestinal digestion using a dynamic rheometer. Cooked potato viscosity dropped considerably upon the action of enzymes from SIF on starch as the digestion progressed. The presence of 0.5% guar gum facilitated the cooked potato matrix to maintain viscosity similar to undigested cooked potato sample throughout the in vitro digestion, which might have resulted in lower starch hydrolysis (%).     

Changes in carbohydrate and glucosinolate composition in white cabbage (Brassica oleracea var. capitata) during blanching and treatment with acetic acid

The effect of blanching and treatment with white vinegar containing acetic acid on dietary fibre, low-molecular-weight carbohydrates and glucosinolates was studied in two cultivars of white cabbage (Heckla and Predikant). The total content of dietary fibre and low-molecular-weight carbohydrates was similar in both cultivars (24 and 60 g/100 g DM, respectively), while the distribution between soluble and insoluble fibre differed (19% was soluble in Heckla versus 26% in Predikant, P < 0.01). Further, Heckla contained higher amounts of glucose and sucrose, while the content of fructose and total glucosinolates was lower than in Predikant. The content of individual glucosinolates differed between the two cultivars. During blanching there was a loss of dry substance (30–34 g/100 g DM), where low-molecular-weight carbohydrates primarily explained the loss (82–90%), but some of the loss was also dietary fibre (about 8%), both soluble fibre containing uronic acids (mainly Predikant) and insoluble ones containing glucose (mainly Heckla). The glucosinolate levels decreased substantially in both cultivars, although the total loss was higher in Predikant (74%) than in Heckla (50%). The individual glucosinolates were affected to different degrees (15–91%). During souring with acetic acid, the content of dietary fibre (primarily insoluble ones) decreased further, while the content of low-molecular-weight carbohydrates was less affected. The total content of glucosinolates was not affected in Heckla but was further reduced in Predikant. There was, however, a substantial increase in 4-methoxyglucobrassicin in both cultivars. It is concluded that blanching and souring decrease the content of carbohydrates and glucosinolates to a great extent and both cultivars behaved similarly. However, individual components were affected differently in the two cultivars.     

Effects of enzymatically-extracted purple rice bran fiber as a protectant of L. plantarum NRRL B-4496 during freezing,freeze drying,and storage

This study investigated purple rice bran fiber (PRF) as a protectant for Lactobacillus plantarum NRRL B-4496 (LP) during freezing, freeze drying and storage. PRF was enzymatically extracted from purple rice bran. L. plantarum NRRL B-4496 was grown in MRS broth, centrifuged, and immobilized on PRF suspension. LP cells immobilized on PRF (LP-PRF) and free LP cell (control) samples were frozen in either air blast (AF) or cryogenic freezing (CF) before freeze drying. Freeze-dried (FLP) samples were stored either at room temperature or at refrigerated temperature. For either freezing method, PRF protected cells had less than one log reduction of viable cells while the control had reductions greater than six logs after freeze drying. The log reductions of viable LP cells protected with PRF after freeze drying and 12 weeks storage at 4° C for AF and CF treatments were 0.7 and 1.3 log cycle, respectively. The viable LP-PRF cell count for CF was significantly lower than for AF after 12 weeks at room temperature. PRF improved LP survival in both AF and CF samples in bile. This study demonstrated that freezing methods affected LP viability during storage and that PRF could protect at both refrigerated and room temperatures.     

Seasonal variation in red deer (Cervus elaphus) venison (M. longissimus dorsi) drip loss,calpain activity,colour and tenderness

Sixty four young red deer (Cervus elaphus) stags (< 2 years old) were slaughtered at four different times (December (Group 1); n = 17, March (Group 2); n = 8, July (Group 3); n = 20 and September (Group 4); n = 19) to evaluate seasonal effects on venison quality. M. longissimus dorsi samples for calpain analysis were collected on the slaughter line and the rest of these muscles were collected at 1 day post-slaughter. Loins were divided into four parts and randomly allocated to storage for 1 day, 3, 9 or 14 weeks at −1.5 °C and then vacuum packaged. Seasonal variation was demonstrated in venison pH. Highly significant positive regressions were found for shear force (P < 0.001) and colour display life (P < 0.001) on pH, where higher pH values were associated with tougher venison and longer colour display life. A clear trend of increasing fluid loss during storage, calculated as amount of purge at 14 weeks of storage minus the amount of drip loss at 1 day post-slaughter, was evident, averaging 2.5% (SEM 0.17) over the four groups. The relative activities of the calpastatin-bound calpain, μ-calpain and m-calpain all exhibited a seasonal pattern although there was no evidence (P > 0.05) that this affected tenderness. There was a highly significant (P < 0.001) negative regression for the average over the four storage times of drip and purge on calpastatin-bound calpain activity.     

Determination of color, pigment, and phenolic stability in yogurt systems colored with nonacylated anthocyanins from Berberis boliviana L. as compared to other natural/synthetic colorants

ABSTRACT:  Anthocyanins are of interest to the food industry because of their antioxidant power, attractive color, and stability in high acid foods. Powder from the Peruvian berry Berberis boliviana Lechler, rich in nonacylated anthocyanins (7% to 8% dry weight), was incorporated into yogurt samples containing 3 different fat levels. Color (CIE L , a , b , chroma, and hue angle), pigment (monomeric anthocyanin and polymeric color), and total phenolics were monitored over 8 wk of storage and compared to yogurt treatments containing purple carrot acylated anthocyanins, red beet betalaines, or FD&C Red nr 40. Anthocyanin profiles were analyzed by HPLC coupled to photodiode array and mass detectors. Color of yogurt containing B. boliviana anthocyanins at 20 mg cyanidin-3-glucoside (cy-3-glu) equivalents/100 g yogurt ( L *= 65, chroma = 14, and hue angle = 335°) was similar to commercial blueberry yogurt ( L *= 65, chroma = 10.5, and hue angle = 341°). High color, pigment, and phenolic stability were observed in yogurts colored with B. boliviana , independent of the fat matrix. Acylated anthocyanins from purple carrot extracts exhibited increased stability with higher fat content. Anthocyanin degradation followed 1st-order kinetics. Pigment half-lives were 125 and 104 d for nonacylated anthocyanins at 10 and 20 mg cy-3-glu equivalents/100 g yogurt and 550.2, 232.6, and 128.9 d for acylated anthocyanins at 20 mg of cy-3-glu equivalents/100 g of 4%, 2%, and 0% fat yogurt. Addition of B. boliviana whole berry powder to yogurt matrices produced an attractive, stable anthocyanin-rich product, eliminating the need for industrial colorant extraction.