Food Science and Technology International

The infusion of yerba mate (YM) Ilex paraguariensis, with its typical bitterness, is traditionally consumed in South America as a mild stimulant beverage. Two types of YM, with sticks (YM-S) and without sticks (YM-L) and three brands for each type were evaluated for caffeine content and the time course of bitterness. The chemical analysis of the six YM infusions at 5% w/v made by high performance liquid chromatography (HPLC) showed that caffeine levels were higher for YM-L brands. The kinetic study of YM bitterness assessed by time-intensity (TI) curves revealed that the presence of sticks lowered maximum intensity, total duration and area under the curve of bitter perception.

Open sun drying is a common method of drying of agricultural products in developing countries. Despite having several disadvantages, it is widely practised because it is a very simple way of drying. Tinospora cordifolia (a type of herb), Curcuma longa L. and Zingiber officinale (spices) were dried in the open sun and determined thermal parameters like product temperature, temperature around the product surface and rate of moisture transfer. The drying time for Tinospora cordifolia, Curcuma longa L. and Zingiber officinale were 41, 43 and 45 sunshine hours respectively with average solar radiation of 10.8MJ/m². Convective heat transfer coefficient (h _c) for Tinospora cordifolia, Curcuma longa L. and Zingiber officinale were 1.57-3.85W/m²°C, 2.32-3.42W/m²°C and 1.62-3.34W/m²°C respectively, and increased by raising the difference in temperature between the product and the temperature around the product surface (T) from 0.3°C to 8.1°C. A fair agreement was observed between fitted and experimental results with coefficient of correlation ranging from 0.9984-0.9921, 0.9960-0.9856 and 0.9983-0.9898 for product temperature, temperature around the product surface and moisture content during drying.

The aim of this work was to study the effect of edible composite coating with different hydrophobic/hydrophilic ratio and solids content (SC) to improve storability of fresh cherries. Cherries cv. Burlat were coated with four edible composite coatings based on locust bean gum (LBG), shellac and beeswax. Three coatings differed on the hydrophobic/hydrophilic ratio (75/25, 50/50 and 25/75) and were applied at constant SC (1.75%). Whereas, one coating was applied at 3.50% SC, maintaining the hydrophobic/hydrophilic ratio at 75/25. Quality was assessed during storage at 1°C up to 11 days followed by 1 day at 20°C. Increasing coating hydrophobicity decreased weight and firmness loss of cherries during storage. Increasing SC did not improve weight and firmness loss, but it increased deterioration index. In general, no benefits were achieved in colour and titratable acidity retention as a result of coating application. Major benefits by coating application were found in weight, firmness and deterioration index. The application of the most hydrophobic solution at 1.75% of SC prolonged the storability of the cherries.

The effect of enzyme amounts used in gastrointestinal in vitro digestion upon the solubility and Caco-2 cell uptake of calcium, iron and zinc from infant formulas (IFs) was studied. Different amounts of enzymes (g enzyme/g IF), pepsin (0.002 and 0.048), pancreatin (0.0005, 0.002 and 0.01) and bile extract (0.003, 0.125 and 0.0625) were assayed. Mineral soluble contents and mineral uptakes by Caco-2 cells were affected by the enzyme amounts used in digestion. Although the highest mineral solubility (Ca 98.6 vs 46.2%; Fe 98.1 vs 83.9%; Zn 98.4 vs 83%) was obtained when the lowest enzyme (pepsin 0.002 vs 0.048; pancreatin 0.0005 vs 0.01g/g IF) and bile extract (0.003 vs 0.0625g/g IF) amounts were used, under these conditions uptake decreased with respect to that obtained when the highest amounts were used (Ca 0.4 vs 1.8%; Fe 0.3 vs 4.8%; Zn 1.7 vs 37%), that indicated a lack of relationship between solubility and absorption. Interactions among different products resulting from the proteolytic activity of digestive enzymes and minerals can modify the physicochemical forms in which minerals are available for absorption after gastrointestinal digestion.

Broken rice flours of three indigenous rice cultivars were utilised for the formulation of tube type pasta (Ziti-cut) using four levels of vital gluten (14-20%, flour weight basis) and gum Arabic (0.5-2.0%, flour weight basis). The textural qualities of pasta were analysed using a texture analyser (TAXT-2i) and by descriptive sensory analysis. The pasta made from native broken rice flour and pre-gelatinised broken rice flour supplementing with vital gluten to obtain 14% protein content were compared for their instrumental texture qualities (hardness and shear strength of raw pasta as well as stickiness and adhesiveness of cooked pasta) and sensory texture analysis (colour, hardness, chewiness, smoothness and grittiness). The pre-gelatinised broken rice flour was found suitable for pasta preparation based on its firmer, larger shear strength and less stickiness and adhesiveness than its native broken rice flour. Among the three varieties, the pre-gelatinised broken rice flour of variety PR-114 with 14% protein content (supplemented by vital gluten) and 1.5% gum Arabic has been found most suitable for the pasta preparation with desirable quality attributes on the basis of instrumental and sensory textural characteristics.

The refining process applied to soybean oil (SBO) in order to obtain the desirable purity characteristics as edible oil, produces chemical changes by partially removing desirable components such as tocopherols. In this study, the effect of temperature (76.4-143.6°C), contact time (6.4-73.6min) and clay amount (0.16-1.84% w/w) on tocopherol content and quality of SBO were evaluated. Neutralised soybean oil was subjected to bleaching using different clay amounts (Tonsil Optimum 320 FF), stirring (250rpm), and partial vacuum (60mmHg). A response surface methodology (RSM) was used to find the parameters that produce bleached oil with minimum peroxide value (PV), maximum tocopherol retention (TOCR) and light colour. The optimal bleaching conditions for SBO were: temperature, 96°C; time, 23min; clay amount, 1.4% w/w oil. Under these conditions, a bleached soybean oil with 0.1meq/kg of PV, 91.74% of TOCR, and colour 1.53 Lovibond red value units was obtained.

This work reviews the methods used for the determination of vitamin D in some dairy products (milk and infant formulas) by high performance liquid chromatography (HPLC). The low vitamin D contents and the presence of interfering compounds require sample treatment and purification of the extract. The advantages and drawbacks of hot and cold saponification, direct extraction and different types of extract purification are also discussed, taking into account the lack of vitamin D stability by heating, exposure to light and oxidation. With respect to chromatographic determination, the mode (normal or reverse phase), type of column (microcolumn or conventional) and detection system (UV, electrochemical and mass spectrometry) are overviewed, considering the vitamers to be determined.

A pilot scale co-rotating, self-wiping twin-screw extruder was used to produce high-moisture texturised meat analogue products from defatted soy protein and lean pork blend with different combinations of operational variables and feed compositions. The effects of operational variables and feed compositions that include temperature setting in five heating zones of the extruder, screw speed, throughput, moisture content, oil content, and pork percentage upon sensory textual quality were determined. The optimal sensory texture and energy consumption of extrusion cooking of the feed blend were obtained with a die of rectangular slit configuration, barrel temperature setting at 60-100-120-150-110°C, screw speed at 80rpm, 50% moisture content, lean pork content ranging from 30-50%, and the oil content ranging from 12-16% (depending upon the fat content of the pork) for optimal extrudate texture formation and stable operation.

Dough physical properties and baking quality of wheat flour substituted by 10% with non germinated quinoa flour (control), 24-h, 48-h and 72-h germinated quinoa flours were studied. The stability time and valorimeter value of the control and 24-h germinated quinoa flour substituted wheat flours were significantly longer and higher than those of 48-h and 72-h samples. The 10% substitution of germinated quinoa flour for wheat flour made distinctly harder dough than that of the control. The low amount of total and inner gas generations was observed for the 48-h and 72-h samples, as compared with those of the control and 24-h germinated quinoa samples. SEM observations showed that the gluten matrix of the control and 24-h germinated quinoa flour substituted wheat dough seemed to be more extended and more dispersed than those of 48-h and 72-h samples. The loaf volume of bread made from 24-h germinated quinoa flour substitution for wheat flour was the largest among the germinated samples; however, no significant differences were observed between the control and 24-h samples.

The aim of this study was to evaluate the effects of ultra high pressure (UHP) on the adductor muscles of bay scallops (Aequipecten irradians) pertaining to certain physicochemical characteristics and microstructure. UHP treatment was applied at 200MPa and 400MPa, each application with one pulse and a holding time of 10min, or 2 pulses and a holding time of 5min per pulse, in a continuous or oscillation mode. Determination of textural parameters and L*, a* and b* colour parameters were carried out and compared with untreated scallops. Microstructure was observed using a scanning electronic microscopy (SEM) technique and, for microbial analyses, a total plate count was performed. SEM showed that UHP treatments induced a size reduction of the honeycomb structure of myofibres, giving a more compact appearance to the structure. Colour and compressibility enhanced by pressure treatment, however loss of hardness was observed. UHP treatments also reduced the initial load in total plate count of microorganisms to 10cfu/g. UHP is a competitive technology in food processing and ready for use on this high-priced seafood product.