Metabolic changes and biochemical degradation during dark anoxic incubation of Nannochloropsis: implications for low-energy microalgal cell rupture.

Dark anoxic incubation has been identified as a low-cost method to facilitate the mechanical rupture of microalgae such as Nannochloropsis via autolysis-induced cell wall thinning. During this process, concentrated slurries of cells are incubated in the dark at an elevated temperature, to deprive them of light and oxygen. This work analyzed the integrity of proteins and lipids during dark anoxic incubation and investigated the cellular responses of Nannochloropsis through an in-depth proteomic analysis.

Vitamin A stability during storage of fortified gari produced using different fortification strategies.

Food fortification is an effective strategy to combat vitamin A deficiency. Gari, a cassava-based West African food product, is an interesting product to fortify with vitamin A, but the low stability of vitamin A poses a challenge. We showed that toasted wheat bran can stabilise vitamin A as retinyl palmitate (RP) during storage of RP-fortified gari to a limited extent.

Conversion of Retinyl Palmitate to Retinol by Wheat Bran Endogenous Lipase Reduces Vitamin A Stability.

Wheat bran can be used as a cost-effective food ingredient to stabilise vitamin A. However, wheat bran endogenous enzymes have been shown to reduce vitamin A stability. In this study, we elucidated the mechanism for this negative effect in an accelerated storage experiment with model systems consisting of native or toasted wheat bran, soy oil and retinyl palmitate (RP).

Visualisation of microalgal lipid bodies through electron microscopy.

In this study, transmission electron microscopy (TEM) and cryo-scanning electron microscopy (cryo-SEM) were evaluated for their ability to detect lipid bodies in microalgae. To do so, Phaeodactylum tricornutum and Nannochloropsis oculata cells were harvested in both the mid-exponential and early stationary growth phase. Two different cryo-SEM cutting methods were compared: cryo-planing and freeze-fracturing.

Mechanistic understanding of the stabilisation of vitamin A in oil by wheat bran: The interplay between vitamin A degradation, lipid oxidation, and lipase activity.

Wheat bran stabilises vitamin A (retinyl palmitate, RP) in oil during storage, but the stabilisation mechanism remains unknown. We here studied the effect of the concentration of RP in oil (0.1-2%) and of RP-enriched oil in the system (5-50%) on the RP retention during accelerated storage of systems with native and toasted wheat bran.

Stabilization of Vitamin A by Cereal Bran: The Importance of the Balance between Antioxidants, Pro-oxidants, and Oxidation-Sensitive Components.

This study investigated the contribution of bran antioxidants and lipids to the stabilizing effect of cereal bran on vitamin A during accelerated storage. Hereto, wheat and rice bran samples subjected to a sequential extraction process were used. Vitamin A stabilization was more pronounced for wheat compared to rice bran.

Oxidative stability differences of aqueous model systems of photoautotrophic n-3 LC-PUFA rich microalgae: The antioxidative role of endogenous carotenoids.

Microalgae rich in omega-3 long-chain polyunsaturated fatty acids (n-3LC-PUFA) have already shown their potential for developing functional food rich in these healthy fatty acids. Not only could they offer a more sustainable alternative for the fish stock that is currently relied upon but is unable to keep up with the demand, enrichment with certain microalgae also leads to oxidatively stable products. Although the reason for this stability has been attributed to the presence of endogenous carotenoids, further insight into their antioxidative role is missing and would be clarifying for selecting the proper microalgae for food enrichment.

Ultrasound-Assisted Extraction of Applewood Polyphenols at Lab and Pilot Scales.

This study focused on the extraction of polyphenols from applewood using ultrasonic-assisted extraction (UAE). First, the influence of solvent composition and mass-volume (m:v) ratio on the extraction yield was studied at a lab scale (200 mL). Overall, a ratio of 1:33 (m:v) resulted in a higher yield of polyphenols.

Stabilisation of vitamin A by wheat bran is affected by wheat bran antioxidants, bound lipids and endogenous lipase activity.

Food fortification is an efficient strategy to combat vitamin A deficiency. However, the stability of vitamin A during storage is low. Cereal bran can be used as a natural and affordable stabilising agent, but the mechanism behind this stabilisation remains unclear.

Antioxidative capacity of microalgal carotenoids for stabilizing n-3LC-PUFA rich oil: Initial quantity is key.

The health-beneficial long-chain omega-3 polyunsaturated fatty acids (n-3 LC-PUFA) are easily affected by the undesired process of lipid oxidation in fish oil, while being stable in the lipid extracts of photoautotrophic microalgae. The current research investigates the role of carotenoids by evaluating the oxidative stability of mixtures of fish oil with total lipid extracts of two different microalgae (Phaeodactylum and Isochrysis) throughout an accelerated storage experiment of 4 weeks at 37 °C. A clear separation between oxidatively stable and oxidatively unstable mixtures was observed for which the initial amount of carotenoids relative to the amount of n-3LC-PUFA was a good indicator.

A simple method for analysis of vitamin A palmitate in fortified cereal products using direct solvent extraction followed by reversed-phase HPLC with UV detection.

Vitamin A is generally analysed using a time-consuming and possibly detrimental saponification step, followed by extraction and HPLC analysis. We here developed a new method to analyse retinyl palmitate (RP) (also known as vitamin A palmitate) without the need for saponification and validated it in model systems consisting of RP, soy oil and wheat bran, and in RP-fortified cereal products. Two direct solvent extraction protocols using acetone/methanol (7/3, v/v) or chloroform/methanol (1/1, v/v) were tested.

The Potential of as a Natural Source of Antioxidants for Fish Oil Stabilization.

Worldwide, fish oil is an important and rich source of the health-beneficial omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA). It is, however, troubled by its high susceptibility towards lipid oxidation. This can be prevented by the addition of (preferably natural) antioxidants.

Photo-Oxidative Stability of Aqueous Model Systems Enriched with Omega-3 Long-Chain Polyunsaturated Fatty Acid-Rich Microalgae as Compared to Autoxidative Stability.

Several species of microalgae are promising as an alternative source of omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA). Photoautotrophic species show the greatest potential, since incorporating them into food products leads to oxidatively stable products; however, the presence of photosensitizers could reduce the shelf-life due to the appearance of photo-oxidation on exposure to light. This study investigated the oxidative impact of illumination for aqueous model suspensions enriched with (phototrophic microalgae─containing potential photosensitizers) and (heterotrophic microalgae─lacking photosensitizers) during storage for 28 days at 37 °C.

Normal-Phase HPLC-ELSD to Compare Lipid Profiles of Different Wheat Flours.

Normal-phase high-performance liquid chromatography (HPLC) is widely used in combination with evaporative light scattering detection (ELSD) for separating and detecting lipids in various food samples. ELSD responses of different lipids were evaluated to elucidate the possibilities and challenges associated with quantification by means of HPLC-ELSD. Not only the number and type of polar functional groups but also the chain length and degree of unsaturation of (free or esterified) fatty acids (FAs) had a significant effect on ELSD responses.

Phase Behavior and Polymorphism of Saturated and Unsaturated Phytosterol Esters.

This study investigated how the physicochemical characteristics of phytosterol esters are influenced by the chain length and degree of unsaturation of the fatty acid ester moiety. Saturated and unsaturated phytosterol esters (PEs) were synthesized by the esterification of different types of fatty acids (stearic, palmitic, lauric, oleic, and linoleic acid) to β-sitosterol. The non-isothermal crystallization and melting behavior of the pure PEs were analyzed.

Impact of Nannochloropsis sp. dosage form on the oxidative stability of n-3 LC-PUFA enriched tomato purees.

Microalgae are a sustainable alternative source of n-3 LC-PUFA that can be incorporated into the food chain either via the incorporation of the (intact or disrupted) biomass or by the incorporation of the oil extracted from the biomass. However, the impact of the dosage form on the enrichment of food products with n-3 LC-PUFA and their oxidative stability has never been described before. This study aims to contribute more insight on the impact of the dosage form of the photoautotrophic microalga Nannochloropsis in enriched tomato puree.

Impact of processing on n-3 LC-PUFA in model systems enriched with microalgae.

Microalgae have already shown their potential as an alternative source of n-3 LC-PUFA. In this study, 5 different microalgal species (Isochrysis, Nannochloropsis, Phaeodactylum, Porphyridium and Schizochytrium) were added to an acidic model system and screened on their potential use in acidic food matrices. The impact of mechanical and thermal processing on the model systems was studied by analyzing the amount of n-3 LC-PUFA, free fatty acids, carotenoids, lipid polymers and the oxidative stability.

Molecular and rheological characterization of different cell wall fractions of Porphyridium cruentum.

Cell wall related polysaccharides of the red microalga Porphyridium sp. were shown to be a promising source of new sustainable thickening agents. Isolated extracellular polysaccharides (EPS) consisted of high molecular weight polymers, showing a higher intrinsic viscosity compared to several commercially used hydrocolloids.

Effect of Meat Type, Animal Fatty Acid Composition, and Isothermal Temperature on the Viscoelastic Properties of Meat Batters.

Unlabelled: The aim of this research was to simultaneously study the effect of meat type (chicken breast and leg meat), animal fatty acid composition (selected pork backfats having a low and high degree of saturation, respectively), and isothermal temperature (50, 60, 70, and 80 °C) on the viscoelastic properties of meat batters during and after application of different time-temperature profiles. Gelation of meat proteins contributed most to the viscoelastic properties of meat batters during heating, whereas crystallization of the lipids especially contributed to the viscoelastic properties during the cooling phase. Although the meat type had little effect on the final viscoelastic properties of the meat product, the fatty acid composition had a clear impact on the melting peak area (and therefore solid fat content) of lard, and subsequently on the final viscoelastic properties of meat batters prepared with different types of fats, with higher G' (elastic modulus) values for the most saturated animal fat.

Impact of different sequences of mechanical and thermal processing on the rheological properties of Porphyridium cruentum and Chlorella vulgaris as functional food ingredients.

Microalgae are a promising and sustainable source for enhancing the nutritional value of food products. Moreover, incorporation of the total biomass might contribute to the structural properties of the enriched food product. Our previous study demonstrated the potential of Porphyridium cruentum and Chlorella vulgaris as multifunctional food ingredients, as they displayed interesting rheological properties after applying a specific combination of mechanical and thermal processing.

Isothermal Crystallization Kinetics of Palm Oil as Influenced by Addition of a Commercial Phytosterol Ester Mixture.

In literature there is good agreement on the health-promoting effects of phytosterols. However, addition of phytosterol esters (PEs) to lipid (containing food products) may influence its crystallization behavior. This study investigated the crystallization kinetics of palm oil (PO) after addition of PEs in high concentrations (≥10%).

The effect of adding a commercial phytosterol ester mixture on the phase behavior of palm oil.

The objective of this study was to investigate in depth the non-isothermal crystallization and melting behavior of binary blends of palm oil (PO) with a commercial, multi-component phytosterol ester (PE) mixture. DSC and time-resolved synchrotron X-ray diffraction (XRD) experiments were conducted on blends with a PE concentration from 0 to 100% at intervals of 10% for DSC and 20% for XRD. Based on XRD, two different ordered structures were identified in pure the PEs.

The transcription factor bZIP14 regulates the TCA cycle in the diatom .

Diatoms are amongst the most important marine microalgae in terms of biomass, but little is known concerning the molecular mechanisms that regulate their versatile metabolism. Here, the pennate diatom was studied at the metabolite and transcriptome level during nitrogen starvation and following imposition of three other stresses that impede growth. The coordinated upregulation of the tricarboxylic acid (TCA) cycle during the nitrogen stress response was the most striking observation.

Flocculation properties of several microalgae and a cyanobacterium species during ferric chloride, chitosan and alkaline flocculation.

Flocculation holds great potential as a low-cost harvesting method for microalgae biomass production. Three flocculation methods (ferric chloride, chitosan, and alkaline flocculation) were compared in this study for the harvesting of 9 different freshwater and marine microalgae and one cyanobacterium species. Ferric chloride resulted in a separation efficiency greater than 90% with a concentration factor (CF) higher than 10 for all species.