FORMATION OF RESISTANT STARCH DURING DEEP-FAT FRYING AND ITS ROLE IN MODIFYING MECHANICAL PROPERTIES OF FRIED PATTIES CONTAINING CORN, RICE, WHEAT, OR POTATO STARCH AND WATER

Resistant starch (RS) was determined in patties (5.1 cm diameter, 1.27 cm high) prepared by mixing starch (corn, rice, wheat, or potato) in distilled water and immersion fried in canola oil (at 170 ± 3C). The RS content (expressed as % of total starch) in corn starch increased from 4.25 to 5.43% (±0.11) in the core region of a patty, whereas in the outer crust region the RS level was constant throughout the frying process. Similar trend was observed in potato, rice, and wheat starch patties. Upon varying the amylose content in the corn starch from 21 to 70%, the initial RS content (prior to frying) increased from 3.47 to 22.74 (±0.11%), following a linear relationship. Maximum force (MF) to puncture the crust of each starch patty was determined for frying duration of 3 to 15 min. Patties exhibiting higher RS content prior to frying, developed crusts with higher MF to puncture the crust, exhibiting a linear relationship between those two variables.     

Surfactant-induced fluorescence changes in fluorescein dye

Addition of non-ionic surfactants revealed changes in the visible absorbance and fluorescence characteristics of fluorescein dyes. Non-ionic surfactants induced a shift in Δ_max, towards shorter wavelengths along with a decrease in absorbance of the dye. On the other hand, addition of anionic surfactants induced a shift of Δ_max, towards longer wavelengths along with enhancement in absorbance and fluorescence. The absorbance value decreased initially, but increased on further addition of cationic surfactant, whereas fluorescence increased initially but decreased on further addition of cationic surfactant. These changes are attributed to the interaction of surfactant micelle with dye molecules, resulting in change of the coloured quinoid form to the colourless lactone form and vice versa.     

DYNAMIC VISCOELASTIC PROPERTIES OF PASTA AS A FUNCTION OF TEMPERATURE AND WATER CONTENT*

Pasta samples were tested in the linear viscoelasticity range using a dynamic mechanical thermal analyzer over the temperature range of 25 to 95C and the water content range of 12 to 20% (weight of water/weight of solids). To obtain wholesome pasta samples at different moisture levels, the intermittent sorption technique was used. The behavior of G′ and tanδversus temperature curves exhibited a transition, which was determined to be the glass transition by making comparisons to the literature values of glass transition for starch and semolina extrudates. At 12.5% water content, glass transition initiated at 48.7C. With increase in water content values, the initiating glass transition temperature decreased. At 19.7% water content, glass transition was observed in the temperature range of 36.9 to 57.3C. Although pasta contains about 13% protein fraction, it did not seem to affect the major part of glass transition range because the pasta proteins become mobile at temperatures greater than 80C and water content greater than 17%.     

Thiamin, Riboflavin, and Nicotinic Acid Contents of Tropical Root Crops from the South Pacific

The thiamin, riboflavin, and nicotinic acid contents of sweet potato (Ipomea batatas, taro (Colocasia esculenta), giant taro (Alocasia macrorrhiza), giant swamp taro (Cyrtosperma chamissonis), taro (Xan-thosoma spp), yam (Dioscorea alata and D. esculenta) were determined for fresh and 40°C dried material obtained from six South Pacific countries. Losses on drying at 40°C for 2-3 days were 10-15% for the three vitamins. Sweet potato contained the largest amount of thiamin (40-120 μg/100g fresh weight) and along with Colocasia esculenta and Xanthosoma spp. the largest amounts of nicotinic acid. The root crops provided inadequate amounts of thiamin, riboflavin, and nicotinic acid with values ranging from 12-123, 12-59 and 220-1310 Hg/100g fresh weight, respectively. Losses on cooking were about the same for all vitamins and root crops, with about a 20% loss on boiling (water retained) or baking and about a 40% loss on boiling (water discarded).     

MATHEMATICAL MODELING OF HEAT AND MOISTURE TRANSFER-RELATED PROPERTIES OF INTERMEDIATE MOISTURE APPLIES

Mathematical models for heat and moisture transfer-related properties of intermediate moisture apples were developed. The models of thermal properties were based on a linear dependence of thermal conductivity on temperature and moisture content, a logarithmic dependence of bulk density on moisture content, and a linear dependence of specific heat on moisture content. The effect of moisture content and temperature on moisture diffusivity was modeled by an exponential relationship. The sorption data were adequately fitted by the Modified Henderson's equation.     

Effect of Sodium Carbonate on the Hydration of Tricalcium Silicate

The effect of sodium carbonate (2%) on the hydration of tricalcium silicate was studied. Free lime, nonevaporable water content, calorimetric measurements, analysis of the liquid phase for Ca²⁺ and OH⁻ ions, zeta potential measurements, and compressive strength measurements were made. The accelerating action of sodium carbonate can be interpreted in terms of adsorption of ions. Further, since sodium carbonate is a structure breaker for water, more free water will be available in the presence of sodium carbonate, which may accelerate the reaction.     

Optically transparent and non-linear LiNbO3: polyimide composite: preparation and characterization

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

EXPERIMENTAL STUDIES OF TEMPERATURE AND MOISTURE MOVEMENT IN WATER LIMITED STARCH BASED FOOD SYSTEMS

Starch and starch/fructose samples were prepared using ct-amylase to hydrolyze starch and formed in a mold to produce 60 × 20 × 5 mm rectangular parallel-piped specimens. Drying experiments using three levels of initial sample moisture content (48, 54, 60% wb). and two levels of drying temperature (48, 88C) were conducted using a computer-controlled connective oven. Results indicated that the     

A Graphical Interpretation of Time-Temperature Related Quality Changes in Frozen Food

Frozen food quality change was presented graphically as a response parameter to the storage variables time and temperature. Computer graphics were used to portray sensory changes in frozen hamburger during storage. The resulting three-dimensional surface (a “quality-response surface”) was simplified by contour plotting and the responses of both full- and partial-history time-temperature indicators were superimposed. Examples of the resulting indicator action diagram were developed for frozen hamburger, and possible applications to frozen inventory management were discussed.     

Changes in Size and Composition of Protein Aggregates on Heating Reconstituted Concentrated Skim Milk at 120oC

Treatment at 120^oC caused initial transfer of protein from the serum and small micelle fraction to the medium-sized micelle fraction. More extensive heating caused transfer of protein from the medium fraction to the large-sized micelle fraction, and the serum fraction as 'soluble’casein. Protein composition of large-sized micelle fraction remained essentially constant, but for the other fractions it changed throughout the heating period. Experiments with heated milks that had been made free of colloidal calcium phosphate (CCP) showed that a proportion of the calcium phosphate in milk, whether indigenous or precipitated by heating, became less soluble. This‘insoluble’calcium phosphate was possibly involved in joining the smaller protein particles into larger-sized aggregates.