Comparative Evaluation of Diagnostic Tools for Oxidative Deterioration of Polyunsaturated Fatty Acid-Enriched Infant Formulas during Storage

Oxidative Quality of Dairy Powders: Influencing Factors and Analysis

Lipid oxidation (LO) is a primary cause of quality deterioration in fat-containing dairy powders and is often used as an estimation of a products shelf-life and consumer acceptability. The LO process produces numerous volatile organic compounds (VOC) including aldehydes, ketones and alcohols, which are known to contribute to the development of off-flavours in dairy powders. The main factors influencing the oxidative state of dairy powders and the various analytical techniques used to detect VOC as indicators of LO in dairy powders are outlined. As the ability to identify and quantify specific VOC associated with LO improves this review highlights how these techniques can be used in conjunction with olfactory and sensory analysis to better understand product specific LO processes with the aim of maximizing shelf-life without compromising quality.

Detection of Lipid Oxidation in Infant Formulas: Application of Infrared Spectroscopy to Complex Food Systems

 Fish- or algal oils have become a common component of infant formula products for their high docosahexaenoic acid (DHA) content. DHA is widely recognized to contribute to the normal development of the infant, and the European Commission recently regulated the DHA content in infant formulas. For many manufacturers of first-age early life nutrition products, a higher inclusion level of DHA poses various challenges. Long-chain polyunsaturated fatty acids (LC-PUFAs) such as DHA are very prone to oxidation, which can alter the organoleptic property and nutritional value of the final product. Traditional methods for the assessment of oxidation in complex systems require solvent extraction of the included fat, which can involve harmful reagents and may alter the oxidation status of the system. A rapid, efficient, non-toxic real-time method to monitor lipid oxidation in complex systems such as infant formula emulsions would be desirable. In this study, infrared spectroscopy was therefore chosen to monitor iron-induced oxidation in liquid infant formula, with conjugated dienes and headspace volatiles measured with GC-MS as reference methods. Infrared spectra of infant formula were recorded directly in mid- and near-infrared regions using attenuated total reflectance Fourier-transform (ATR-FTIR) and near-infrared (NIRS) spectrophotometers. Overall, good correlation coefficients (R2 > 0.9) were acquired between volatiles content and infrared spectroscopy. Despite the complex composition of infant formula containing proteins and sugars, infrared spectroscopy was still able to detect spectral changes unique to lipid oxidation. By comparison, near-infrared spectroscopy (NIRS) presented better results than ATR-FTIR: prediction error ATR-FTIR 18% > prediction error NIRS 9%. Consequently, NIRS demonstrates great potential to be adopted as an in-line or on-line, non-destructive, and sustainable method for dairy and especially infant formula manufacturers.

Nosy confirmation: reconstitution of the characteristic odor of softwood via quantitative analysis and human sensory evaluation

The significance of wood odors beyond flavoring effects for barbecues and wine aged in barrels has recently been under discussion. Wood has an immense influence on our physical and mental condition through our palate, such as positive health and mood-stimulating effects. As a result of increased public interest, the key odorants from various natural wood species were recently decoded. To gain profound insights into the contribution of single odorants to the overall scent of distinct wood types, this study compares several softwood species (Scots pine, incense cedar, European larch, Norway spruce, and white fir) by odor profile analysis. Nine odor-active constituents, which were previously detected in those woods, were quantified using stable isotope dilution analysis (SIDA). Odor activity values (OAVs) calculated on the basis of odor thresholds (OTs) determined in cellulose revealed hexanal, octanal, (E)-non-2-enal, p-cresol, vanillin, and thymoquinone as dominant odorants for wood odor. Recombination experiments by mixing the odorants in their naturally occurring concentrations in a cellulose matrix confirmed the successful characterization of the key odorants for Scots pine and incense cedar wood.

Determination of Volatiles by Odor Activity Value and Phenolics of cv. Ayvalik Early-Harvest Olive Oil

Ayvalik is an important olive cultivar producing high quality oils in Turkey. In the present study, volatile and phenolic compositions of early-harvest extra virgin olive oil (cv. Ayvalik) were determined. The solvent-assisted flavor evaporation (SAFE) technique was used for the extraction of volatile components. The aromatic extract obtained by SAFE was representative of the olive oil odor. A total of 32 aroma compounds, including alcohols, aldehydes, terpenes, esters, and an acid, were identified in the olive oil. Aldehydes and alcohols were qualitatively and quantitatively the most dominant volatiles in the oil sample. Of these, six volatile components presented odor activity values (OAVs) greater than one, with (Z)-3-hexenal (green), hexanal (green-sweet) and nonanal (fatty-pungent) being those with the highest OAVs in olive oil. A total of 14 phenolic compounds were identified and quantified by liquid chromatography combined with a diode array detector and ion spray mass spectrometry. The major phenolic compounds were found as 3,4-DHPEA-EDA, 3,4-DHPEA-EA and p-HPEA-EDA.

The aroma of goat milk: seasonal effects and changes through heat treatment

Goat milk was characterized and analyzed by human sensory evaluation and gas chromatography/olfactometry (GC/O). Most potent odor-active compounds were determined in (a) raw goat's milk from two different seasons and (b) heated goat's milk after different treatment intensities. A trained panel found sensorial differences between winter and summer milks (seasonal effect) and milks from different farms (farm-specific effect). A total of 54 odor-active compounds with flavor dilution (FD) factors ≥8 were detected of which 42 odorants were identified. 4-Ethyloctanoic acid, 3-methylindole (skatol) and one unknown compound (RI 2715) showed highest intensities in all raw milks. With heat treatment, goat-like, stable-like, and (cooked) milk-like odor characteristics decreased while caramel-like or vanilla-like notes increased. In total, 66 odor-active compounds were detected in heated goat milks (FD ≥ 8). To the best of our knowledge, only 16 of the 42 identified odorants were reported before in raw goat's milk. Additionally, for the first time the presence of 1-benzopyran-2-one (coumarin) could be confirmed in ruminant milk.