Natural antioxidants produced in oxidized lipid/amino acid browning reactions

Natural phospholipids: Occurrence, biosynthesis, separation, identification, and beneficial health aspects

During the last years, phospholipids (PLs) have attracted great attention because of their crucial roles in providing nutritional values, technological and medical applications. There are considerable proofs that PLs have unique nutritional benefits on human health, such as reducing cholesterol absorption, improving liver functions, and decreasing the risk of cardiovascular diseases. PLs are the main structural lipid components of cell and organelle membranes in all living organisms, and therefore, they occur in all organisms and the derived food products. PLs are distinguished by the presence of a hydrophilic head and a hydrophobic tail, consequently they possess amphiphilic features. Due to their unique characteristics, the extraction, separation, and identification of PLs are critical issues to be concerned. This review is focused on the content of PLs classes in several sources (including milk, vegetable oils, egg yolk, and mitochondria). As well, it highlights PLs biosynthesis, and the methodologies applied for PLs extraction and separation, such as solvent extraction and solid-phase extraction. In addition, the determination and quantification of PLs classes by using thin layer chromatography, high-performance liquid chromatography coupled with different detectors, and nuclear magnetic resonance spectroscopy techniques.

Physico-chemical and sensory property changes in almonds of Desmayo Largueta variety during toasting / Cambios en las propiedades físico-químicas y sensoriales de almendras de la variedad Desmayo Largueta durante el tostado

Almonds modify their properties during toasting due to the high temperatures reached. The aim of this study was to evaluate the physico-chemical and sensory property changes in shelled almonds, Desmayo Largueta variety harvested in Tarragona (Spain) and toasted at 200 and 220°C. Internal tem perature and moisture content were determined in almonds during toasting, and fatty acid composi tion, the index of acidity, the peroxide value and the TBA test in almond oil. Sensory analysis of almonds with different toasted intensity was performed. Rancidity was also evaluated by sensory analysis after a year of storage. There was a delay in the internal temperature increase of the almonds between 120 and 130 °C, which coincided with the period of maximum rate of water evaporation. There was no significant variation in the fatty acid composition of the almond oil during toasting. The peroxide value of almond oil had a slight increase from 6 min at 220°C and from 8 min at 200°C, reaching a maximum at 10 min. Rancidity after a year of storage increased up to 8 min and then decreased. The maximum crispiness was obtained at the end of the period of a maximum rate of water evaporation: between 6 and 8 min of toasting at 220 °C and between 8 and 10 min of toasting at 200°C. Over-toasting produced an antioxidant effect in the product, but decreased sweetness and increased bitterness and grittiness.

Antioxidative activity of amino phospholipids and phospholipid/amino Acid mixtures in edible oils as determined by the Rancimat method

Phosphatidylethanolamine (PE), phosphatidylcholine (PC), lysine (Lys), and mixtures of them were tested for antioxidative activity in refined olive oil by the Rancimat method to investigate the role of the chemical reactions produced in the Rancimat vessel on the induction periods (IPs) obtained. PE and Lys, but not PC, increased the IPs of the oil when tested alone. In addition, PE/Lys and PC/Lys mixtures, but not PC/PE mixtures, exhibited a synergistic effect. All these results can be understood considering the in situ formation of oxidized lipid/amino compound reaction products with antioxidative activities. Thus, the formation of pyrroles could be detected after derivatization with p-(dimethylamino)benzaldehyde, and some of these compounds could be unambiguously identified by GC-MS after their conversion into volatile derivatives. In addition, the formed products contributed to the color developed, and a correlation was observed between the Rancimat IPs obtained and the yellowness index of the oxidized oils recovered from the Rancimat. Furthermore, the differences observed in the antioxidative activities of PE, PC, Lys, and their mixtures could be explained according to the lipophility and hydrophility of the oxidized lipid/amino compound reaction products formed. All these results suggest that chemical reactions are being produced in the Rancimat vessel and the Rancimat IPs obtained are a consequence of the antioxidative activities of the products formed in these reactions. Furthermore, Rancimat may be a valuable tool for testing antioxidative activities of antioxidants produced during food processing if favorable conditions for antioxidant formation are employed.