Production, characterization, and potential applications of lipopeptides in food systems: A comprehensive review.

Lipopeptides are a class of lipid-peptide-conjugated compounds with differing structural features. This structural diversity is responsible for their diverse range of biological properties, including antimicrobial, antioxidant, and anti-inflammatory activities. Lipopeptides have been attracting the attention of food scientists due to their potential as food additives and preservatives. This review provides a comprehensive overview of lipopeptides, their production, structural characteristics, and functional properties. First, the classes, chemical features, structure-activity relationships, and sources of lipopeptides are summarized. Then, the gene expression and biosynthesis of lipopeptides in microbial cell factories and strategies to optimize lipopeptide production are discussed. In addition, the main methods of purification and characterization of lipopeptides have been described. Finally, some biological activities of the lipopeptides, especially those relevant to food systems along with their mechanism of action, are critically examined.

Effect of consumption of sheep and cow milk on rat brain fatty acid and phospholipid composition.

The effect of sheep milk and cow milk on the lipid composition of rat brain was investigated in two feeding experiments of 28-days duration. Total lipids of the rat brain were extracted using ethanol-hexane, and the fatty acids and phospholipid contents analysed using gas chromatography with flame ionization detection (GC-FID) and phosphorus-31 nuclear magnetic resonance (31P NMR). Furthermore, freeze-dried pooled samples were analysed using attenuated total reflectance Fourier Transform Infrared and Fourier Transform Raman Spectroscopy and analysed with multivariate methods. A significantly (P < 0.05) higher C18:2 content was found in the cow milk group compared with sheep milk-treated groups in Study one. In Study two, a significantly (P < 0.05) lower C16:0 content was present in the sheep milk-treated group compared to the control low Ca/P group. No significant (P > 0.05) differences were observed in the spectroscopy analyses. It is concluded that sheep and cow milks fed to rats for 28-days had a low effect on the brain lipidome.

Earth Worming-An Evaluation of Earthworm (Eisenia andrei) as an Alternative Food Source.

Aside from their bioremediation roles, little is known about the food and feed value of earthworms. In this study, a comprehensive evaluation of the nutritional composition (proximate analysis and profiles of fatty acids and minerals) and techno-functional properties (foaming and emulsion stability and capacity) of earthworm (Eisenia andrei, sourced in New Zealand) powder (EAP) were investigated. Lipid nutritional indices, ω6/ω3, atherogenicity index, thrombogenicity index, hypocholesterolemic/hypercholesterolemic acid ratio, and health-promoting index of EAP lipids are also reported. The protein, fat, and carbohydrate contents of EAP were found to be 53.75%, 19.30%, and 23.26% DW, respectively. The mineral profile obtained for the EAP consisted of 11 essential minerals, 23 non-essential minerals, and 4 heavy metals. The most abundant essential minerals were potassium (8220 mg·kg-1 DW), phosphorus (8220 mg·kg-1 DW), magnesium (744.7 mg·kg-1 DW), calcium (2396.7 mg·kg-1 DW), iron (244.7 mg·kg-1 DW), and manganese (25.6 mg·kg-1 DW). Toxic metals such as vanadium (0.2 mg·kg-1 DW), lead (0.2 mg·kg-1 DW), cadmium (2.2 mg·kg-1 DW), and arsenic (2.3 mg·kg-1 DW) were found in EAP, which pose safety considerations. Lauric acid (20.3% FA), myristoleic acid (11.20% FA), and linoleic acid (7.96% FA) were the most abundant saturated, monounsaturated, and polyunsaturated fatty acids, respectively. The lipid nutritional indices, such as IT and ω-6/ω-3, of E. andrei were within limits considered to enhance human health. A protein extract derived from EAP (EAPPE), obtained by alkaline solubilisation and pH precipitation, exhibited an isoelectric pH of ~5. The total essential amino acid content and essential amino acid index of EAPPE were 373.3 mg·g-1 and 1.36 mg·g-1 protein, respectively. Techno-functional analysis of EAPPE indicated a high foaming capacity (83.3%) and emulsion stability (88.8% after 60 min). Heat coagulation of EAPPE was greater at pH 7.0 (12.6%) compared with pH 5.0 (4.83%), corroborating the pH-solubility profile and relatively high surface hydrophobicity (1061.0). These findings demonstrate the potential of EAP and EAPPE as nutrient-rich and functional ingredients suitable as alternative food and feed material. The presence of heavy metals, however, should be carefully considered.

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.

Positional Distribution of Fatty Acids in Processed Chinook Salmon Roe Lipids Determined by 13C Magnetic Resonance Spectroscopy (NMR).

Recently, there has been great interest in the lipidomic of marine lipids and their potential health benefits. Processing of seafood products can potentially modify the characteristics and composition of lipids. The present study investigated the effect of processing methods (salting and fermentation) on the positional distribution of fatty acids of Chinook salmon roe using 13C nuclear magnetic resonance spectroscopy (NMR). The NMR analysis provided information on the carbonyl atom, double bond/olefinic, glycerol backbone, aliphatic group, and chain ending methyl group regions. The obtained data showed that docosahexaenoic acid (DHA) is the main fatty acid esterified at the sn-2 position of the triacylglycerides (TAGs), while other fatty acids, such as eicosapentaenoic acid (EPA) and stearidonic acid (SDA), were randomly distributed or preferentially esterified at the sn-1 and sn-3 positions. Fermentation of salmon roe was found to enrich the level of DHA at the sn-2 position of the TAG. The processing of roe by both salt drying and fermentation did not appear to affect the proportion of EPA at the sn-2 position. This present study demonstrated that fish roe processing can enhance the proportion of DHA at the sn-2 position and potentially improve its bioavailability.

Physicochemical Characteristics, Techno-Functionalities, and Amino Acid Profile of Prionoplus reticularis (Huhu) Larvae and Pupae Protein Extracts.

The amino acid profile, techno-functionalities (foaming stability/capacity, emulsion stability/capacity, solubility, and coagulation), and physicochemical characteristics (colour, particle size, surface hydrophobicity, Fourier-transform infrared spectroscopy, and differential scanning calorimetry) of protein extracts (PE) obtained from Prionoplus reticularis (Huhu grub) larvae (HLPE) and pupae (HPPE) were investigated. Total essential amino acid contents of 386.7 and 411.7 mg/g protein were observed in HLPE and HPPE, respectively. The essential amino acid index (EAAI) was 3.3 and 3.4 for HLPE and HPPE, respectively, demonstrating their nutritional equivalence. A unique nitrogen-to-protein conversion constant, k, and the corresponding protein content of the extracts were 6.1 and 6.4 and 72.1% and 76.5%, respectively. HLPE (37.1 J/g) had a lower enthalpy than HPPE (54.1 J/g). HPPE (1% w/v) exhibited a foaming capacity of 50.7%, which was higher than that of HLPE (41.7%) at 150 min. The foaming stability was 75.3% for HLPE and 73.1% for HPPE after 120 min. Both protein extracts (1% w/v) had emulsifying capacities that were 96.8% stable after 60 min. Therefore, protein extracts from Huhu larvae and pupae are of a good nutritional quality (based on their EAAI) and have techno-functional properties, such as foaming and emulsification, that afford them potential for certain food technology applications.

Physicochemical, biochemical and microbiological changes of jeotgal-like fermented Chinook salmon (Oncorhynchus tshawytscha) roe.

A jeotgal-like product was processed from Chinook salmon (Oncorrhynchus tshawytscha) roe. Physicochemical, biochemical, and microbiological compositions were studied during 30 days of fermentation. Fermentation decreased water activity (aw) and pH value. Total bacterial and LAB counts (log CFU/g) increased up to 12 days of processing and then no further changes occurred. Saturated fatty acids (SFA) decreased (p < 0.05), monounsaturated fatty acids (MUFA) did not change (p > 0.05), whereas fermentation time improved polyunsaturated fatty acids (PUFA) content significantly (p < 0.05). Astaxanthin, lutein and phospholipids (PC, LPC, PE, LPE and LPS) concentrations were found to increase, while cholesterol and tocopherol contents were decreased at the end of the fermentation (p < 0.05). This study indicates that the nutritional value of salmon roe can be enhanced by fermentation.

Use of fungal and bacterial protease preparations to enhance extraction of lipid from fish roe: Effect on lipidomic profile of extracted oil.

The present study investigated the hydrolysis of protein in hoki roe homogenate using a HT (bacterial), a FP-II (fungal) protease preparations and Alcalase (bacterial) to enhance lipid yield extraction. The degree of hydrolysis was determined at various pH, temperature and time using casein and hoki roe. Total lipid extraction and lipidomic analysis was carried out following proteolysis of hoki roe homogenate. The degree of hydrolysis and SDS-PAGE revealed that the hydrolytic capability of Alcalase was better than HT and FPII. The total extracted lipid yield was better following hydrolysis with Alcalase (19.29 %), compared to HT (18.29 %) and FPII (18.33 %). However, the total phospholipid (PL) and n-3 fatty acid yields were better from HT hydrolysed hoki roe homogenate (PL = 30.7 µmol/g; n-3 = 10.5 %), compared to Alcalase (PL = 22 µmol/g; n-3 = 5.95 %). Overall, this study indicates that HT protease preparation hydrolysis of fish roe homogenate can both enhance lipid extraction and retain lipid quality.

The effect of pulsed electric fields on the extracted total lipid yield and the lipidomic profile of hoki roe.

The effect of pulsed electric fields (PEF) at different field strengths (0.62, 1.25, 1.875 kV/cm) and frequencies (25, 50, 100 Hz) on total lipid extraction from hoki roe was investigated, along with the lipidomic profile (total lipid, phospholipid, fatty acid, phospholipid composition, and positional distribution of EPA and DHA). High PEF input (112 kJ/kg, 1.875 kV/cm and 100 Hz) yielded the highest total lipid (16.2% wet weight (WW)), and phospholipid (46 µmol/g WW) contents, without affecting n-3 fatty acid content (32%), and generated the highest LDPG, LPE, LPS and LPC contents (1.1, 0.41, 6.13 and 2.15 µmol/g WW, respectively). However, this PEF treatment resulted in sn-2 phospholipid EPA and DHA to be relocated to the sn-1,3 positions. Despite the good yield of n-3 fatty acids and PL, high PEF intensity treatment was found to result in negative structural changes in hoki roe lipids.

Effect of Pulsed Electric Fields on the Lipidomic Profile of Lipid Extracted from Hoki Fish Male Gonad.

Processing of hoki, a commercially important fish species, generates substantial quantities of co-products, including male gonad, which contains valuable lipids, such as phospholipids, that could be recovered and utilised. Hoki fish male gonads (HMG) were subjected to pulsed electric fields (PEF) treatment at varying field strengths (0.625, 1.25, and 1.875 kV/cm) and frequencies (25, 50, and 100 Hz), at a fixed pulse width of 20 µs. The total lipid was extracted using an ethanol-hexane-based (ETHEX) extraction method, and the phospholipid and fatty acid compositions were determined using 31P NMR and GC-FID, respectively. The total lipid yield was increased from 4.1% to 6.7% by a relatively mild PEF pre-treatment at a field strength of 1.25 kV/cm and frequency of 50 Hz. A higher amount of EPA (8.2%), DPA (2.7%), and DHA (35.7%) were obtained by that treatment, compared to both un-heated (EPA: 8%; DPA: 2.5%; DHA: 35.2%) and heat-treated controls (EPA: 7.9%; DPA: 2.5%; DHA: 34%). No significant changes to the content of the major phospholipids were observed. PEF pre-treatment under mild conditions has potential for improving the total lipid yield extracted from fish male gonad.

A simple method for enrichment of ß-lactoglobulin from bovine milk whey involving selective hydrolysis by two fungal protease preparations.

Two commercially available food grade fungal protease preparations (Fungal Protease 31,000 and Fungal Protease 60000) were found to hydrolyse bovine acid whey proteins but left the beta-lactoglobulin (ß-Lg) intact under the processing conditions used. Comparative analysis before and after hydrolysis of bovine acid whey, by 1D- and 2D-PAGE, RP-HPLC and intact-mass mass spectrometry showed that the ß-Lg remains intact and in high yield after hydrolysis by the fungal proteases. The ß-Lg could be separated from the whey protein peptide hydrolysate by ultrafiltration. Subjecting whey fraction to hydrolysis with the fungal protease preparations provides a procedure, under relatively mild conditions, to generate a highly enriched ß-Lg fraction. ß-Lg is recognised as a valued material in the food, pharmaceutical and cosmetic industries due to its properties such as gelling and foaming. The enriched ß-Lg preparation would also have application in areas such as nanoencapsulation.

Analysis of peptides in a sheep beta lactoglobulin hydrolysate as a model to evaluate the effect of peptide amino acid sequence on bioactivity.

Fungal protease FPII was found to hydrolyse sheep ß-lactoglobulin (ß-Lg), and the hydrolysate exhibited substantial antioxidant and ACE inhibition bioactivities. From analysis of the peptide sequences in the hydrolysate in relation to bioactivity, synthetic peptides corresponding to four regions of sequence in ß-Lg (LAFNPTQLEGQCHV, DTDYKKYLLF, LDAQSAPLRVY and VEELKPTPE) were analysed for bioactivity. Additional synthetic peptides were designed to examine the bioactivity of different parts of the above four sequences, and the effect of amino acid substitutions on bioactivity. The results show that parts of the peptide sequences contribute differently to bioactivity and substitution of amino acids has a substantial effect on antioxidant and ACE inhibition activities.

Amino Acid Sequences of Lactoferrin from Red Deer (Cervus elaphus) Milk and Antimicrobial Activity of Its Derived Peptides Lactoferricin and Lactoferrampin.

Although the bioactivities of bovine lactoferrin have been extensively investigated, little is known about deer milk lactoferrin bioactivity and its amino acid sequence. This research investigated the amino acid sequence of deer lactoferrin and the antimicrobial activities of two lactoferrin-encrypted peptides; lactoferricin (Lfcin) and lactoferrampin (Lfampin). Deer lactoferrin was found to have a molecular weight of 77.1 kDa and an isoelectric point of 7.99, which are similar to that of bovine lactoferrin, 78 kDa and pI 7.9. Deer lactoferrin contains 707 amino acids, one amino acid less than bovine lactoferrin, and has 92% homology with bovine lactoferrin. Deer lactoferricin exhibited strong antimicrobial activity against E. coli American Type Culture Collection (ATCC) 25922 and L. acidophilus ATCC 4356. The antimicrobial activities of deer and bovine Lfcin and Lfampin were compared. Based on MIC, deer Lfcin was found to be a more effective inhibitor of L. acidophilus ATCC 4356 than bovine Lfcin, but bovine Lfcin and Lfampin were more effective against E. coli ATCC 25922 than deer Lfcin and Lfampin. The deer Lfcin sequence differed at seven amino acids from bovine Lfcin and this decreased the net positive charge and increased the hydrophobicity. Deer Lfampin contained two differences in amino acid sequence compared to bovine Lfampin which decreased the net positive charge. These amino acid sequence differences likely account for differences in antibacterial activity. Positive charge and hydrophobic residues provide the amphipathic character of these helical peptides, and are considered important for binding of antimicrobial peptides. In silico modelling of deer Lfcin indicated an identical α-helical structure compared to bovine Lfcin.

Lipidomic signature of Pacific lean fish species head and skin using gas chromatography and nuclear magnetic resonance spectroscopy.

The present study investigated the lipid profile (fatty acid profile, positional distribution of n-3 fatty acids and phospholipid content) of head and skin of three lean fishes (gurnard, ribaldo and snapper). Gurnard head (GH) and snapper head (SnH) were found to contain a higher amount of total lipid (5.9-6.3%) than other samples (1.2-3.9%) including a considerable amount of bioactive n-3 fatty acids such as EPA (GH = 9.05%; SnH = 5.06%), DPA (GH = 2.78% ; SnH = 2.93%) and DHA (GH = 12.8% ; SnH = 7.72%) in the polar lipid fraction. DHA was found to predominate in the sn-2 position for gurnard head and snapper head. Partial least squares discriminant analysis showed that both gurnard and snapper samples were positively correlated with the n-3 fatty acids (EPA, DPA and DHA). Gurnard and snapper head had higher phospholipid content than the skin. Therefore, among the studied samples, GH and SnH are the best source of bioactive n-3 phospholipids.

Positional distribution of fatty acids and phospholipid composition in King salmon (Oncorhynchus tshawytscha) head, roe and skin using nuclear magnetic resonance spectroscopy.

This study used a novel extraction method (ETHEX) to extract the lipid content of King salmon head, skin and roe, and determined the lipid profiles using GC-FID, 13C NMR and 31P NMR spectroscopy. On a wet tissue basis, King salmon roe was found to contain the highest amount of phospholipid (26.53 µmol/g) and n-3 fatty acids (43.32%), followed by head (PL = 10.76 µmol/g; n-3 = 7.21%) and skin (PL = 4.98 µmol/g; n-3 = 8.23%). Total EPA (6.62%) and DHA (28.83%) content, along with the sn-2 positioned EPA (3.25%), DPA (1.36%) and DHA (16.35%) were also higher in roe compared with head and skin. The highest amount of EPA (7.99%) and DHA (34.47%) contents were found in the polar lipid fractions of roe, followed by skin (EPA = 4.19%; DHA = 25.95%) and head (EPA = 2.61%; DHA = 17.85%). This result suggests that salmon roe could be used for developing n-3 phospholipid enriched products.

Effect of salted-drying on bioactive compounds and microbiological changes during the processing of karasumi-like Chinook salmon (Oncorhynchus tshawytscha) roe product.

The physicochemical, biochemical and microbiological changes of karasumi-like Chinook salmon (Oncorrhynchus tshawytscha) roe were determined during 20 days of salted-drying processing. Colour parameters (L*, a*, and b*), water activity (aw) and the pH value decreased at the end of the processing. Total bacterial and LAB counts (log CFU/g) varied over the processing period. Saturated fatty acids, such as palmitic acid (C16:0) and stearic acid (C18:0), and unsaturated fatty acids such as palmitoleic acid (C16:1), oleic acid (C18:1), and arachidonic acid (C20: 4), were significantly decreased (p < 0.05), but conversely, gamma-linolenic acid (C18:3), and eicosapentaenoic acid (C22:5) were increased (p < 0.05) by salted-drying time. Cholesterol and tocopherol contents were reduced, while the astaxanthin and lutein contents were increased (P < 0.05) during the salted-drying process. Salmon karasumi-like product is a high nutrition product that contains a substantial content of functional compounds.

Omega-3 phospholipids in Pacific blue mackerel (Scomber australasicus) processing by-products.

The present study investigated phospholipid content, fatty acid composition and the positional distribution (sn-1,3 and sn-2) of n-3 fatty acids in four blue mackerel processing by-products (head, skin, roe, and male gonad). Total lipid was extracted using hexane/ethanol (1:2) and the analyses were carried out using NMR and GC-FID techniques. On the basis of g wet tissue, blue mackerel roe was a better source of phospholipids (38.6 µmol), compared to head (9.89 µmol), skin (13.5 µmol), and male gonad (10.0 µmol). Total lipid extracted from roe was found to have a higher proportion of n-3 fatty acids (44.4%) including EPA (11.3%) and DHA (27.5%), compared to head (total n-3 = 36.6%; EPA, 9.08%: DHA, 21.9%), skin (total n-3 = 34.8%; EPA, 9.63%; DHA, 19.5%) and male gonad (total n-3 = 42.5%; EPA, 12.1%; DHA, 24.7%). The proportion of EPA in the sn-2 position was substantially higher in fish roe (12.6%) compared to the other by-products (head, 1.91%; skin, 2.22%; male gonad, 2.02%). However, the DPA and DHA content in the sn-2 position did not vary significantly among the various parts (p > 0.05). Phospholipid esterified n-3 fatty acids were higher in roe (55.5%) compared to head (40.9%), skin (21.8%) and male gonad (32%). The present study suggests that blue mackerel roe is the best source of marine n-3 phospholipids among the blue mackerel commercially produced by-products.

Marine omega-3 (n-3) phospholipids: A comprehensive review of their properties, sources, bioavailability, and relation to brain health.

For several decades, there has been considerable interest in marine-derived long chain n-3 fatty acids (n-3 LCPUFAs) due to their outstanding health benefits. n-3 LCPUFAs can be found in nature either in triglycerides (TAGs) or in phospholipid (PL) form. From brain health point of view, PL n-3 is more bioavailable and potent compared to n-3 in TAG form, as only PL n-3 is able to cross the blood-brain barrier and can be involved in brain biochemical reactions. However, PL n-3 has been ignored in the fish oil industry and frequently removed as an impurity during degumming processes. As a result, PL products derived from marine sources are very limited compared to TAG products. Commercially, PLs are being used in pharmaceutical industries as drug carriers, in food manufacturing as emulsifiers and in cosmetic industries as skin care agents, but most of the PLs used in these applications are produced from vegetable sources that contain less (without EPA, DPA, and DHA) or sometimes no n-3 LCPUFAs. This review provides a comprehensive account of the properties, structures, and major sources of marine PLs, and provides focussed discussion of their relationship to brain health. Epidemiological, laboratory, and clinical studies on n-3 LCPUFAs enriched PLs using different model systems in relation to brain and mental health that have been published over the past few years are discussed in detail.

Simple and Efficient One-Pot Extraction Method for Phospholipidomic Profiling of Total Oil and Lecithin by Phosphorus-31 Nuclear Magnetic Resonance Measurements.

The present study reports an efficient method using ethanol and hexane for lipid extraction (ETHEX) that is simpler and faster than the FOLCH (methanol/chloroform) and PALC (ethanol/hexane, a multi-step and time-consuming method) methods for determination of the phospholipid (PL) and fatty acid contents, using hoki roe as a model system. Substantial differences were found with the PALC and ETHEX methods, resulting in higher total lipid (14.6 ± 0.35 and 14.3 ± 0.08%, respectively) and lecithin (4.95 ± 0.08 and 4.89 ± 0.35%, respectively) yields compared to the FOLCH method (total lipid, 12.9 ± 0.35%; lecithin, 3.15 ± 0.35%). Phospholipids (LDPG, CL, LPS, SM, PE, LPC, PI, and PC) were found to partition in the methanol aqueous layer with the FOLCH method. Better phosphorus-31 nuclear magnetic resonance resolution and detection of PL, including lyso-PL, was obtained using D2O. The best extraction and detection of PL was achieved with the novel ETHEX method using D2O.