Effect of formulation and processing conditions on the rheological and textural properties of a semi-liquid syrup model

The effect of two hydrocolloids, the overall composition and stirring rate of a confectionery semi-liquid syrup model, were studied by means of the measure of rheological properties, instrumental texture evaluation and turbidity. A syrup model was made with sucrose, high fructose corn syrup, gum (dextran or carrageenan), citric acid and water. An experimental design based on Taguchi’s method was employed to evaluate the influence of sugar concentration, gum type, gum concentration, citric acid concentration and stirring rate. An analysis of variance was performed. From all evaluated properties (except turbidity), °Brix was the factor that showed the maximum influence, with higher values on textural properties (adhesive force, cohesive work and stringiness). The gum type had influence over viscosity, hardness, adhesive force and turbidity. The Newtonian behavior predominated in the syrups and viscosity of samples was affected by the variables studied. The mean values of viscosity, hardness and adhesive force for all samples with carrageenan were higher than those obtained with dextran (at both °Brix levels).     

Chemical composition of date pits and reproductive hormonal status of rats fed date pits

Five isonitrogenous (23% CP) and isocaloric (2.8 Mcal/kg) diets with or without date pits were fed to rats to evaluate the effect of feeding date pits on the reproductive hormonal status of male and female rats. Proximate analysis of date pits indicated that the nitrogen-free extract (NFE) was 71.5%, in which 3% was starch. When chemical analysis was based on dietary fibre, the NFE was found to be 26.7% only, in which 20.9% is mannose. The dietary treatments had no effect on testosterone level in male rats. While, oestradiol concentration in the serum of female rats decreased significantly as the percent of date pits increased, this may be due to the estrogenic effect of date pits, which may cause reduction in the fertility of the female rats.     

High pressure processing in jam manufacture: effects on textural and colour properties

High hydrostatic pressure-treated strawberry jam samples were examined with respect to their textural and colour properties, the aim being to establish the relationship between pectin concentration, texture and colour. Samples were prepared with varying amounts of pectin (0.1, 0.5, 2.5, 5, 7.5 and 10% w/w) and were processed using the same parameters (400 MPa, for 5 min at 25°C). After preparation, the samples were rheologically tested using a cone and plate configuration on a Creep Viscometry Oscillation rheometer. A colour spectrophotometer was used to monitor (at 505 nm) the changes in colour during storage. Comparing these experimental samples with commercially available samples of high pressure and traditional strawberry jams, it was found that the best texture was achieved when the pectin concentration was between 2.5 and 5% w/w. With increasing pectin concentration, the storage and loss moduli (indicators of liquid- and solid-like characteristics) were increased. Colour was found to be affected by the increasing pectin concentration, as the absorbance intensity was decreased, suggesting a relation between pectin and anthocyanin degradation.     

Common date palm in Tunisia: chemical composition of pulp and pits

Date pulp and seeds (Phoenix dactylifera L.) of a mixture of some mature common varieties called ‘Khalti’, from the South‐Eastern region of Tunisia, were evaluated for their main chemical composition. Studies were also conducted on the profiles of the extracted oil fatty acid. The following average values (on a dry‐weight basis) were obtained from the pulp and pits, respectively: total sugars 63.38% and 8.12%, reducing sugars 51.56% and 6.63%, sucrose 11.82% and 1.49%, protein 3.86% and 5.31%, oil 0.26% and 8.33%. Gas–liquid chromatography revealed that the major unsaturated fatty acid was linoleic acid (32.77%) for the pulp and oleic acid (47.66%) for the pits, while the main saturated fatty acid was palmitic acid (20.55%) for the pulp and lauric acid (17.39%) for the pits. Myristic, stearic and linolenic acids were also found in both the pulp and seeds. The uses of common dates, which are currently used only for animal feed, are assessed with suggestions for potential uses as sources of nutraceutical fructose and edible, pharmaceutical oils.     

Preliminary analysis and potential uses of date pits in foods

Date pits were examined for extractable high value-added components for including in functional foods. The objectives of this research were to conduct preliminary analysis of the pits from three leading varieties in UAE and to identify potential uses in foods. Date pits were odourless and had light to dark brown colour and a bland taste with slight bitterness. They contained 7.1–10.3% moisture, 5.0–6.3% protein; 9.9–13.5% fat; 46–51% acid detergent fibre; 65–69% neutral detergent fibre; and 1.0–1.8% ash. More than half of the pit protein could not be extracted consecutively with NaCl, ethanol and acetic acid. Pits had a substantial amount of oil that needed to be characterized for constituent components, biological activities and stability. Pits contained large quantities of fibre and, possibly, resistant starch that may have potential health benefits. Further research is needed to characterize isolated components and search for bioactive constituents with antimicrobial, antioxidant and other health-promoting activities.     

Traditional and industrial oven-dry processing of olive fruits: influence on textural properties,cell wall polysaccharide composition,and enzymatic activity

The preparation of table olives according to the Italian traditional “Ferrandina” method (Fer) includes an initial blanching step of black Cassanese olives, followed by salting and oven-drying. Its industrial implementation, also called the “Sybaris” method (Syb), replaces the blanching procedure by cutting the olives followed by immersion in water. The measurement of tensile properties showed that the Fer processing increased the weakness, softness, and deformability of the skin and the flesh of olive fruits, while the flesh of the Syb fruits became stronger and stiffer. These differences are probably correlated to the degradation and/or reorganisation of cell wall polysaccharides in the fruits. The degradation of pectic and hemicellulosic polysaccharides in the Fer olives was inferred by their increased solubility in aqueous solutions. Contrarily, retention of pectic polysaccharides was observed in Syb olives. As no correlation was found between cell wall degrading enzymatic activities and cell wall polysaccharides extractability, it is probable that these modifications were driven by heat.     

Potential effects of ultrafiltration process and date powder on textural,sensory, bacterial viability,antioxidant properties and phenolic profile of dromedary Greek yogurt

The aim of this study was to improve textural and antioxidant capacity of dromedary yogurt using ultrafiltration process and date powder. Ultrafiltration increased total solids content of dromedary milk within the range considered optimal to develop yogurt. Texture profile of Greek yogurt fortified with date powder (GYD) improved considerably compared to control. Sample of GYD are more appealing to consumer than control. LC-ESI-MS analysis of GYD extracts allowed the identification of fifteen phenolic compounds, among which quinic acid and cirsiliol were found to be the major phenolic acid and flavonol, respectively. GYD exhibited the highest DPPH•-radical scavenging activity, Fe²⁺ chelating capacity and Fe³⁺ reducing power. The follow-up of physical and microbiological stability of GYD and control during cold storage showed that date powder significantly increased bacterial counts and decreased syneresis. Therefore, ultrafiltration and date powder could be valued as effective tool to solve the poor consistency of dromedary milk products.     

Beef and sheep mortadella: formulation, processing and quality aspects

Beef and lamb mortadella samples were prepared under controlled conditions and stored for 16 weeks under refrigeration. Moisture, protein, fat, ash and sodium chloride contents were measured initially and pH, percentage of free fatty acids, thiobarbituric acid values, total volatile nitrogen content, residual nitrite concentration and microbiological status were determined at regular intervals throughout storage. The sensory quality of the mortadellas during the first 2 months of storage was evaluated. The results of these tests permitted assessment of the quality and safety of beef and lamb mortadella. The products were satisfactory with regard to chemical and microbiological analyses, but after 2 months storage, the poor colour of lamb mortadella limited the sensory acceptability. Measurements of rancidity, caused by lipid deterioration and protein breakdown, were the best indicators of product quality.     

Some properties of corn starches II: Physicochemical,gelatinization, retrogradation,pasting and gel textural properties

The physicochemical, thermal, pasting and gel textural properties of corn starches from different corn varieties (African Tall, Ageti, Early Composite, Girja, Navjot, Parbhat, Partap, Pb Sathi and Vijay) were studied. Amylose content and swelling power of corn starches ranged from 16.9% to 21.3% and 13.7 to 20.7 g/g, respectively. The enthalpy of gelatinization (ΔH_gel) and percentage of retrogradation (%R) for various corn starches ranged from 11.2 to 12.7 J/g and 37.6% to 56.5%, respectively. The range for peak viscosity among different varieties was between 804 and 1252 cP. The hardness of starch gels ranged from 21.5 to 32.3 g. African Tall and Early Composite showed higher swelling power, peak, trough, breakdown, final and setback viscosity, and lower ΔH_gel and range of gelatinization. Pearson correlations among various properties of starches were observed. Gelatinization onset temperature (T_o) was negatively correlated to peak-, breakdown-, final- and setback viscosity (r = −0.809, −0.774, −0.721 and −0.686, respectively, p < 0.01) and positively correlated to pasting temperature (r = 0.657, p < 0.01). ΔH_gel was observed to be positively correlated with T_o, peak gelatinization temperature and (T_p) and gelatinization conclusion temperature T_c (r = 0.900, 0.902 and 0.828, respectively, p < 0.01) whereas, it was negatively correlated to peak- and breakdown- (r = −0.743 and −0.733, respectively, p < 0.01), final- and setback viscosity (r = −0.623 and −0.611, respectively, p < 0.05). Amylose was positively correlated to hardness (r = 0.511, p < 0.05) and gumminess (r = 0.792, p < 0.01) of starch gels.     

Rheological,textural, micro-structural and sensory properties of mango jam

Mango jam behaved as pseudoplastic fluid exhibiting yield stress. The Herschel–Bulkley (HB) model described adequately the steady-state rheological behavior of jam. Temperature dependence of the consistency index followed Arrhenius relationship. Time dependent structural breakdown characteristics of mango jam followed Hahn model. Hardness of mango jam increased with pectin concentration and acidity. Hardness increased up to 60% sugar concentration but decreased with further increase in sugar concentration at all pH and pectin levels. Stickiness, work of shear, and adhesion did not show any systematic trend with pH, pectin, and sugar concentration. The overall acceptability was rated highest for mango jam prepared with 65% sugar, 1% pectin at pH 3.4. Principal component analysis (PCA) revealed that hardness and work of shear are the most relevant among all the characteristics (physicochemical, sensory, textural, rheological, and compositional) studied for mango jam. Microstructure of mango jam was found to be composed of network regions with large pores as well as dense, compact regions with small pores.     

Saponins: properties, applications and processing

Saponins are a diverse group of compounds widely distributed in the plant kingdom, which are characterized by their structure containing a triterpene or steroid aglycone and one or more sugar chains. Consumer demand for natural products coupled with their physicochemical (surfactant) properties and mounting evidence on their biological activity (such as anticancer and anticholesterol activity) has led to the emergence of saponins as commercially significant compounds with expanding applications in food, cosmetics, and pharmaceutical sectors. The realization of their full commercial potential requires development of new processes/processing strategies to address the processing challenges posed by their complex nature. This review provides an update on the sources, properties, and applications of saponins with special focus on their extraction and purification. Also reviewed is the recent literature on the effect of processing on saponin structure/properties and the extraction and purification of sapogenins.     

Effect of minimal processing on the textural and structural properties of fresh‐cut pears

The feasibility of minimal processing and modified atmosphere packaging to preserve the original textural quality of fresh‐cut pears was evaluated throughout storage under refrigeration. Fresh‐cut pear firmness could be extended up to several weeks with low‐O₂ atmospheres. A packaging atmosphere of 100% N₂ combined with the use of plastic bags with an O₂ permeability of 15 cm³ m^?2 bar^?1 day^?1 maintained cell structure and partially avoided membrane breakdown and exudate accumulation in intercellular spaces. Under the other conditions studied, pear texture underwent dramatic deterioration, which could be related to complete inundation of the extracellular environment. Firmness decreased linearly throughout the storage period studied, with rate constants ranging from 0.0097 to 0.040 day^?1. The consideration of other textural variables also gave valuable information, similar to that provided by firmness data. © 2002 Society of Chemical Industry     

Tamarind seed: properties, processing and utilization

Tamarind seed is an underutilized byproduct of the tamarind pulp industry. Only a small portion of the seed, in the form of tamarind kernel powder (TKP), is used as a sizing material in the textile, paper, and jute industries. Though many applications of this seed are possible, there have been hardly any other uses for it including using it as an additive in food formulations. The excellent gelling cum adhesive characteristics of the decorticated seed powder can lead to several applications in food and pharmaceutical industries which are evident by the number of research papers as well as patent applications. This article thus focuses on the possibilities of using the seed in several food and non-food industries with particular reference to physical and engineering properties, hydration behavior, rheological properties, functional and nutritional characteristics, and the processing of the tamarind seed for wider applications.     

Physicochemical,morphological, thermal,pasting, and textural properties of starch acetates

Acetylated starches are a commercially important group of modified starch known for their reduced retrogradation tendency, high clarity, low viscosity, high swelling power, and lower gelatinization temperature and time. Due to these remarkable properties, acetylation is a commonly used chemical modification for preparing stabilized starches. This review summarizes the methods used for preparation of starch acetates and corresponding effects of acetylation on morphological, thermal, pasting, digestibility, textural, and other functional characteristics of starches isolated from various botanical sources. Starch acetates are also useful as packaging material, as wall material for encapsulating active ingredients, and to improve the storage stability of different products.     

枣在我国加工利用现状及发展趋势

概述了枣的营养价值以及国内枣加工现状 ,并就如何加速枣产业化提出一些建议。