Authors:M. Hódsági, Á. Jámbor, E. Juhász, S. Gergely, T. Gelencsér, and A. Salgó
Resistant starches (RSs) are broadly investigated as appropriate additives in starch-based products due to their well-known and proved health benefits. However, it was shown in previous studies that these starches are sensitive of the different heat treatments used in the food processing, which can cause changes, especially in the resistance. There is an increasing trend to use microwave (MW) energy in food processing; therefore, our aim was to investigate the changes of RSs compared to native starches caused by MW heating. Maize, wheat, RS2 and RS4 starches were MW-treated according to a 2×2 experimental design (300 and 600 W of power, 30 and 150 s of time). The changes of in vitro digestibility, rheological properties (rapid visco analyser, RVA) and near infrared (NIR) spectroscopic characteristic were studied. Two spectrophotometers were applied (dispersive and Fourier-transform (FT)) to compare their sensitivity in the analysis of the MW-treated starches.Results showed that the digestibility of starches did not show any tendencies when increasing the microwave energy of treatments, the characteristics of the kinetic curves remained unchanged. The RVA analysis showed that the RSs did not gelatinize after the heat-treatments. The MW heating weakened the rheological properties of all starches. The NIR analysis was the most sensitive device for the detection of the effects of MW treatments. The analysis of the most characteristic carbohydrate regions (2080–2130 and 2270–2290 nm) highlighted structural alterations of the starches; moreover, the dispersive spectrophotometer was found to be more sensitive in the analysis of starches than the FT-one.
Increasing awareness of the health benefits of n-3 fatty acids has led to studies related to the manipulation of the fatty acid composition of animal products. These fatty acids, especially eicosapentaenoic acid (EPA; C20:5n-3) and docosahexaenoic acid (DHA; C22:6n-3), are abundant in foods of marine origin. Fish consumption is, however, limited by seasonal availability, affordability and consumers' preference. Recent studies on the provision of n-3 fatty acid rich foods have therefore centred on the enrichment of products such as poultry meat through feeding fish oil diets. However, decreased quality (storage and flavour) has been associated with products from poultry fed such diets. Other dietary sources of n-3 fatty acids such as fish meal and plant seed oils result in minor improvement of the quality and low levels of EPA and DHA in the enriched product. Supplementation of high levels of vitamin E or other synthetic antibiotics in diets may increase oxidative stability and hence the storage quality of n-3 fatty acid enriched broiler meat. However, their reported influence on off-flavour is conflicting. Other methods of reducing off-flavour in enriched meat involving the use of processed n-3 PUFA sources although may reduce off-flavour, result in reduced deposition of EPA and DPA. Marine algae (MA) is an attractive source of n-3 fatty acids because it is a primary rich source of DHA and contains naturally occurring carotinoids, which are useful for their antioxidant activity. Investigations into the use of MA and identification of cheaper sources of n-3 PUFA for the enrichment of broiler chicken are needed. In addition, the search for viable methods of reducing off-flavour in n-3 enriched broiler meat should continue. The production of high quality and affordable broiler meat is essential for realising the full benefits associated with the consumption of n-3 fatty acid enriched products.
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