Rapid screening on aflatoxins' presence in Pistachia vera nuts using diffuse reflectance infrared Fourier transform spectroscopy and chemometrics.

Aflatoxin contamination in pistachios has been analyzed in this work, using Diffuse Reflectance Infrared Spectroscopy (DRIFTS) with chemometrics. Forty-nine Greek pistachio samples of different aflatoxin concentrations were classified into aflatoxin and non-aflatoxin groups using the 3035-2821, 1770-1721, 1570-1481 and 1260-1061 cm-1 spectral regions in Kubelka-Munk conversion and first derivative form. A chemometric model was developed using twenty-eight samples as calibration, 11 as validation and 10 as test set. The discrimination analysis separated correctly the 100% of the calibration and the validation set and the 80% of the test set. The proposed chemometric model is simple, rapid, economical and environmentally friendly since it does not require chemical pre-treatment of the samples. It is expected that the present method may be proved useful in food industry and the inspection authorities as a rapid decision-making tool to detect batches that must be rejected and enhance consumers' protection from aflatoxin contaminated pistachios.

The effect of salt concentration on swelling power, rheological properties and saltiness perception of waxy, normal and high amylose maize starch.

The effect of salt concentration on swelling power, rheological properties and saltiness perception of waxy, normal and high amylose maize starch was investigated. The swelling power decreased with increasing salt concentration from 0% to 2.0% among all starch samples. Waxy starch showed the highest swelling power at different salt levels, while high amylose starch showed the least swelling power. The salt addition increased the gelatinization temperature of waxy starch and normal starch from 71.3 °C to 77.1 °C and from 72.3 °C to 78.2 °C. Their storage modulus (G'), loss modulus (G''), and viscosity values at lower salt concentration were greater than those at higher salt concentration. The increasing tan δ of waxy and normal starch against frequency sweep indicated liquid-like behavior, while high amylose starch exhibited decreasing tan δ indicating solid-like behavior as it was difficult to gelatinize. When sensory evaluation was conducted by trained panelists, it was found that high amylose starch displayed the highest initial saltiness and in-mouth saltiness intensity, accompanied by the greatest thickness, lubrication and stickiness, while waxy starch displayed the lowest values for saltiness perception and mouthfeel.

Effect of Particle Orientation during Thermal Processing of Canned Peach Halves: A CFD Simulation.

The objective of this work was to apply Computational Fluid Dynamics (CFD) to study the effect of particle orientation on fluid flow, temperature evolution, as well as microbial destruction, during thermal processing of still cans filled with peach halves in sugar syrup. A still metal can with four peach halves in 20% sugar syrup was heated at 100 °C for 20 min and thereafter cooled at 20 °C. Infinite heat transfer coefficient between heating medium and external can wall was considered. Peach halves were orderly placed inside the can with the empty space originally occupied by the kernel facing, in all peaches, either towards the top or the bottom of the can. In a third situation, the can was placed horizontally. Simulations revealed differences on particle temperature profiles, as well as process F values and critical point location, based on their orientation. At their critical points, peach halves with the kernel space facing towards the top of the can heated considerably slower and cooled faster than the peaches having their kernel space facing towards the bottom of the can. The horizontal can case exhibited intermediate cooling but the fastest heating rates and the highest F process values among the three cases examined. The results of this study could be used in designing of thermal processes with optimal product quality.

Effect of different iron compounds on wheat and gluten-free breads.

BACKGROUND: Iron fortification of bread often results in sub-optimal quality of the final product due to undesirable changes in the physical characteristics and sensory properties of the bread. In this study both the form of iron (soluble, insoluble or encapsulated) and the type of bread (wheat or gluten-free) were varied in order to investigate the effect of iron and gluten on the product characteristics. RESULTS: The effect of iron on the quality characteristics of the breads investigated depended on iron type, but not on iron solubility. Colour, crust firmness, specific volume, cell number and uniformity as well as aroma were the attributes that were mainly affected in iron-enriched wheat bread. In some cases, specific volume was 30% lower than that of the control sample, while cell uniformity was significantly lower, as low as 50% of the control sample in some fortified samples. In gluten-free breads, differences between unfortified and fortified samples included colour, crust firmness, cell number, 'moisture' odour, metallic taste and stickiness. In some cases, the sensory scores were better for fortified samples. CONCLUSIONS: Differences due to iron fortification were less pronounced in gluten-free compared to wheat breads. The choice of the appropriate iron compound which will not cause adverse quality changes is still a challenge.