Performance of crude olive pomace oil and soybean oil during carotenoid production by Blakeslea trispora in submerged fermentation

Crude olive pomace oil (COPO) and crude soybean oil (CSO), two low-cost carbon sources, were examined as cosubstrates of glucose for carotenoid production by Blakeslea trispora. Results were compared to those obtained in glucose as a sole carbon source (medium 1) and glucose plus the respective end-line refined oil counterparts. Microbial growth in the presence of oils resulted in an increase in total carotenoid production. The performance of crude oils was better than that of the respective refined forms. Carotenoid production depended on both type and added oil amount. An increase in added oil amount did not necessarily favor carotenoid accumulation. The addition of 10 g oil/L of substrate stimulated carotenoid synthesis, mainly that of beta-carotene, more than 14 (COPO) and 40 times (CSO) in comparison to that observed in medium 1. The maximum total carotenoid content (as mg beta-carotene per g of biomass dry weight) was 75 (COPO) and 235 mg (CSO), respectively. Growth, substrate assimilation, and lipid accumulation-degradation also depended on the presence of oil in the substrate.     

Kinetics of individual crocetin ester degradation in aqueous extracts of saffron (Crocus sativus L.) upon thermal treatment in the dark

Kinetics of individual crocetin ester degradation in aqueous extracts of saffron upon thermal treatment in the dark has been studied. Special attention has been paid to the comparison between saffron extracts and aqueous solutions of a crocetin ester rich fraction, with a lower stability of the latter observed. The degradation reaction was the same for all crocetin esters whether they were in saffron extracts or whether they were purified, although it was affected by external factors that modified their kinetic and thermodynamic parameters, making some of them less stable than others.     

Use of reference compounds in antioxidant activity assessment

The choice of reference compounds is examined as a "critical control point" of antioxidant activity assessment. Gallic, caffeic, sinapic, uric, and ascorbic acids, isoeugenol, and Trolox were tested using different redox (FRAP, Folin-Ciocalteu) and radical scavenging (DPPH*, ABTS*+, CBA, ORAC) assays. The ability to chelate transition metals was assessed to support some of the findings. Analytes were also tested in liposomes. On the basis of the findings, we do not recommend uric acid (due to solubility constrains) and ascorbic acid (due to fast degradation kinetics) as references. The behavior of the rest of the compounds could not always be attributed to typical structural characteristics. Selection of suitable reference compounds for in vitro antioxidant activity assays is not an easy task to achieve. The choice of reference compounds has to remain at the convenience of the researchers, with regard to the aim of the study.