Influence of deep-fat frying process on phospholipid molecular species composition of Sardina pilchardus fillet

Effect of plasma-activated water (PAW) soaking on the lipid oxidation of sardine (Sardina pilchardus) fillets

The efficacy of plasma-activated water (PAW) as a chemical-free and environmentally friendly preservative has been documented for a variety of foods, but the onset of lipid oxidation induced by plasma-reactive species has been less extensively studied. In this work, global indices (peroxide value, UV specific absorbance) and direct analytical determinations of volatile and non-volatile oxidation products were performed on sardine lipids extracted from fish fillets immersed in PAW (treatments) and distilled water (controls) for 10-30 min. Evidence of PAW-induced lipid oxidation was provided by higher UV specific absorbances and higher levels of C5-C9 secondary volatile oxidation products in the treated samples. However, the degree of fatty acid oxidation was not sufficient to cause a significant reduction in nutritionally valuable eicosapentaenoic acid and docosahexaenoic acid. Twelve cholesterol oxidation products (COPs) were identified in the sardine lipids, but no significant differences in total COPs content were found between PAW processed and control samples.

Impact of Modern Oven Treatments on Lipid Oxidation and Vitamin E Content of Fillets from Sardine (Sardina pilchardus) at Different Reproductive Cycle Phases

The beneficial effects of sardine consumption can be related to the presence of bioactive compounds, such as vitamin E and ω3 polyunsaturated fatty acids. In any case, the levels of these compounds in sardine fillet depend on different factors mainly related to the diet and reproductive cycle phase of the fish as well as the technological treatments carried out to cook the fillets. The aim of the present study is two-fold: first, to evaluate changes in the total fatty acid profile, lipid oxidation, and vitamin E content of raw fillets from sardine (Sardina pilchardus) at different reproductive cycle phases (pre-spawning, spawning, and post-spawning); and second, to highlight how these nutritional profiles are affected by three oven treatments (conventional, steam, and sous-vide). For this purpose, raw fish was grouped into pre-spawning, spawning, and post-spawning phases according to the mesenteric fat frequency and the gonadosomatic index evaluation, and submitted to conventional (CO), steam (SO), and sous-vide (SV) baking. The ratio of EPA/DHA and vitamin E increased from post-spawning to pre-spawning, to spawning. Considering the reproductive phases, baking affected the oxidative degree differently: a CO > SO ≥ SV impact was found in the worst scenario (post-spawning), mitigated by vitamin E, to CO ≥ SO > SV in the best scenario (spawning). SV was the best treatment with high values of vitamin E in pre-spawning individuals (110.1 mg/kg). This study shows how vitamin E is correlated to the combined effect of endogenous and exogenous factors.

Physicochemical and Volatile Flavor Properties of Fish Skin under Conventional Frying, Air Frying and Vacuum Frying

The aim of this study was to investigate the physicochemical characteristics and volatile flavor of fried tilapia skins under three frying methods. Conventional deep-fat frying usually increases the oil content of the fried fish skin and leads to lipid oxidation, which reduces the product quality. Alternative frying methods, such as air frying for 6 and 12 min under 180 °C (AF6, and AF12) and vacuum frying at 0.085 MPa for 8 and 24 min under 120 °C (VF8, and VF24) were compared to conventional frying for 2 and 8 min under 180 °C (CF2, and CF8) for tilapia skin. Physical properties of fried skin, such as the moisture content, water activity, L* values and breaking force decreased under all frying methods, while the lipid oxidation and a*, b* values increased with the increase in frying time. In general, VF offered higher hardness of product compared to AF which had a lower breaking force. Especially AF12 and CF8 had the lowest breaking force, which indicated higher crispness. For the oil quality inside the product, AF and VF reduced conjugated dienes formation and retarded oxidation compared to CF. The results of the flavor compositions of fish skin measured using gas chromatography mass spectrometry (GC/MS) with solid phase microextraction (SPME) showed that CF obtained higher unpleasant oily odor (nonanal, 2,4-decadienal, etc.), while AF presented greater grilling flavor (pyrazine derivatives). Because fish skin fried by AF only relied on hot air, Maillard reaction derived compounds, such as methylpyrazine, 2,5-dimethylpyrazine, and benzaldehyde were the leading flavors. This made the aroma profiles of AF very different from VF and CF. Among all the approaches, AF and VF developed lower oil content, mild fat oxidation and better flavor attributes, which proves their practical applications for frying tilapia fish skin.

Marine Fish-Derived Lysophosphatidylcholine: Properties, Extraction, Quantification, and Brain Health Application

Long-chain omega-3 fatty acids esterified in lysophosphatidylcholine (LPC-omega-3) are the most bioavailable omega-3 fatty acid form and are considered important for brain health. Lysophosphatidylcholine is a hydrolyzed phospholipid that is generated from the action of either phospholipase PLA1 or PLA2. There are two types of LPC; 1-LPC (where the omega-3 fatty acid at the sn-2 position is acylated) and 2-LPC (where the omega-3 fatty acid at the sn-1 position is acylated). The 2-LPC type is more highly bioavailable to the brain than the 1-LPC type. Given the biological and health aspects of LPC types, it is important to understand the structure, properties, extraction, quantification, functional role, and effect of the processing of LPC. This review examines various aspects involved in the extraction, characterization, and quantification of LPC. Further, the effects of processing methods on LPC and the potential biological roles of LPC in health and wellbeing are discussed. DHA-rich-LysoPLs, including LPC, can be enzymatically produced using lipases and phospholipases from wide microbial strains, and the highest yields were obtained by Lipozyme RM-IM®, Lipozyme TL-IM®, and Novozym 435®. Terrestrial-based phospholipids generally contain lower levels of long-chain omega-3 PUFAs, and therefore, they are considered less effective in providing the same health benefits as marine-based LPC. Processing (e.g., thermal, fermentation, and freezing) reduces the PL in fish. LPC containing omega-3 PUFA, mainly DHA (C22:6 omega-3) and eicosapentaenoic acid EPA (C20:5 omega-3) play important role in brain development and neuronal cell growth. Additionally, they have been implicated in supporting treatment programs for depression and Alzheimer’s. These activities appear to be facilitated by the acute function of a major facilitator superfamily domain-containing protein 2 (Mfsd2a), expressed in BBB endothelium, as a chief transporter for LPC-DHA uptake to the brain. LPC-based delivery systems also provide the opportunity to improve the properties of some bioactive compounds during storage and absorption. Overall, LPCs have great potential for improving brain health, but their safety and potentially negative effects should also be taken into consideration.

Quality changes of repeatedly fried palm oil and extracted oil from fried loach

Fried loach is a kind of popular flavor food. The effects of repeated frying on peroxide value (PV), acid value (AV), P-anisidine value (P-AV), total polar components (TPC) and free fatty acids (FFA) of palm oil and extracted oil from fried loach (EOL) were studied. The loach was fried in palm oil at 170 °C for 3 min and the frying was repeated 10 times. The oil from fried loach was collected and analyzed. The results showed that the TPC of palm oil exceeded the standard limit (3 mg/g) when frying 10 times. The PV and TPC of EOL were unqualified after 9 and 4 times frying (19.17 meq O2/kg and 31% respectively). The AV of the EOL reached 2.46 mg/g after 9 times frying. Palm oil has better frying performance than EOL because of its balanced proportion of saturated and unsaturated fatty acids. Palm oil can be used for 9 times frying, while the EOL has been damaged after 4 times.

Virgin Olive Oil as Frying Oil

Frying is one of the oldest cooking procedures and is still among the most popular ones for food preparation. Due to their unique sensory characteristics, fried foods are consumed often and with pleasure. During frying, part of the oil is absorbed by the food, thereby becoming part of our diet; most interestingly, in the Mediterranean area approximately 50% of total fat intake is provided by cooking fats. Olive oil is the key lipid component of the Mediterranean diet, the health-promoting effects of which have been largely attributed to olive oil intake. Olive oil is unique among vegetable oils due to its desirable lipid profile and some of its minor components. Scientific evidence now indicates that during frying olive oil behavior is usually equal or superior to that of refined vegetable oils. Herein, an overview of virgin olive oil performance under frying is given, with special reference to the fate of olive oil microconstituents. The compositional changes of foods fried in olive oil are also reviewed and discussed in detail.

Zwitterionic hydrophilic interaction solid-phase extraction and multi-dimensional mass spectrometry for shotgun lipidomic study of Hypophthalmichthys nobilis

Zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC) material was used as solid-phase extraction sorbent for purification of phospholipids from Hypophthalmichthys nobilis. The conditions were optimized to be pH 6, flow rate 2.0mL·min(-1), loading breakthrough volume ⩽5mL, and eluting solvent 5mL. Afterwards, the extracts were analyzed by multi-dimensional mass spectrometry (MDMS) based shotgun lipidomics; 20 species of phosphatidylcholine (PC), 22 species of phosphatidylethanoamine (PE), 15 species of phosphatidylserine (PS), and 5 species of phosphatidylinositol (PI) were identified, with content 224.1, 124.1, 27.4, and 34.7μg·g(-1), respectively. The MDMS method was validated in terms of linearity (0.9963-0.9988), LOD (3.7ng·mL(-1)), LOQ (9.8ng·mL(-1)), intra-day precision (<3.64%), inter-day precision (<5.31%), and recovery (78.8-85.6%). ZIC-HILIC and MDMS shotgun lipidomics are efficient for studying phospholipids in H. nobilis.

Changes in the Fatty Acid Profile and Phospholipid Molecular Species Composition of Human Erythrocyte Membranes after Hybrid Palm and Extra Virgin Olive Oil Supplementation

This work aims to evaluate and compare, for the first time, the effects of extra virgin olive oil (EVOO) and hybrid palm oil (HPO) supplementation on the fatty acid profile and phospholipid (PL) molecular species composition of human erythrocyte membranes. Results supported the effectiveness of both HPO and EVOO supplementation (3 months, 25 mL/day) in decreasing the lipophilic index of erythrocytes with no significant differences between HPO and EVOO groups at month 3. On the other hand, the novel and rapid ultraperformance liquid chromatography-tandem mass spectrometry method used for PL analysis reveals an increase in the levels of phosphatidylcholine and phosphatidylethanolamine species esterified with polyunsaturated fatty acids. This work demonstrates the ability of both EVOO and HPO to increase the degree of unsaturation of erythrocyte membrane lipids with an improvement in membrane fluidity that could be associated with a lower risk of developing cardiovascular diseases.