Major dietary lipids in nutrition and health.

In this chapter, an overview of the major lipids in the diet with emphasis in nutritional aspects is provided. Triacylglycerols, i.e., glycerol esterified with three fatty acids, are the predominant constituents in dietary lipids. Therefore, this chapter focuses on the nature and nutritional significance of the main fatty acids in the diet and their possible modifications during food processing and commercialization. The main fatty acids in dietary lipids are grouped into saturated, monounsaturated and polyunsaturated fatty acids. Nutritional implications, the latest intervention trials and health recommendations will be discussed. A brief description of the major sources of lipids in the diet is included, oils and fats standing out. Other food sources shortly commented are milk and dairy products, meat, poultry and eggs, fish, and structured lipids designed to improve functional and nutritional properties. Modifications of fatty acids as a result of processing and commercialization are discussed because of their great relevance for their health implications, especially oxidation compounds and trans fatty acids.

Risk/Benefit Evaluation of Chia Seeds as a New Ingredient in Cereal-Based Foods.

Chia seed (Salvia hispanica L.) is a food rich in protein, fiber, polyunsaturated fatty acids and antioxidants. Consequently, its incorporation in food formulations may be desirable from a nutritional and healthy point of view. However, there is concern regarding the formation of process contaminants when they are subjected to thermal processing. The objective of this study was to incorporate different amounts of ground chia seeds in a biscuit model to evaluate the effect on the antioxidant capacity and formation of acrylamide and furfurals. Seven standard "Maria-type" biscuit formulations were prepared, replacing wheat flour with different amounts of ground chia seeds (defatted and non-defatted), from 0% (control biscuit) to 15% (respect to total solids in the recipe). Samples were baked at 180 °C for 22 min. Compared with the control biscuit, chia formulations increased the content of nutrients, antioxidant capacity (ABTS) and phenolic compounds (Folin-Ciocalteau method) but also doubled acrylamide levels and even raised more than 10 times furanic compound concentrations. Results indicate that the use of chia seeds as ingredients in new cereal-based formulations would improve the nutritional profile but also increase the occurrence of chemical process contaminants. This paradox should be carefully considered in the context of risk/benefit analysis.

Formation of process contaminants in commercial and homemade deep-fried breadcrumbs.

Breading is a culinary technique widespread throughout the world. Deep-frying breaded foods forms a palatable crust but also promotes the formation of compounds of toxicological relevance. The influence of the composition of breadcrumbs on the risk associated with the formation of acrylamide, hydroxymethylfurfural (HMF), and furfural was investigated in a deep-fried breadcrumb coating model. Commercial (CBC) and homemade (HBC) wheat-based breadcrumbs were characterized by the reducing sugars and the asparagine content among other parameters (moisture, pH, and CIELab color). The formation of process contaminants in fried breadcrumbs were not influenced by their initial content, but they were affected by the precursors level. The HMF content was significantly higher (1.4 times) in fried HBC (172 mg/kg) than in CBC (120 mg/kg). By contrast, the acrylamide content was 3 times higher in fried CBC (332 µg/kg) than in HBC (111 µg/kg). Multivariate analysis shows that asparagine is the limiting factor for acrylamide formation, and the reducing sugar content is the main determinant for the formation of furanic compounds. A signal value of 463 µg/kg is proposed for the acrylamide content in the coating of deep-fried breaded foods. The reducing sugars and asparagine content in breadcrumb coatings should be considered when designing breaded foods, thereby reducing the formation and consequently the dietary exposure to these potentially harmful compounds.

Incorporation of hydroxytyrosol alkyl esters of different chain length as antioxidant strategy in walnut oil spray-dried microparticles with a sodium alginate outer layer.

Omega-3 rich vegetable oils, such as walnut oil, are gaining interest because of their health benefits. Synthetized homologous series of hydroxytyrosol alkyl esters (HTEs) with different alkyl chain lengths (C4-C18) were incorporated in purified walnut oil (PWO) spray-dried microparticles, designed with Capsul® (C) as encapsulating agent and sodium alginate (SA) as outer layer (PWO-C/SA). The encapsulation efficiency (>87%) and Tg of PWO-C/SA microparticles were not affected by the HTEs. The incorporation of HTE-C10 increased the melting point (185.0 ± 1.3 °C), decreasing the formation of Dimers + Polymers (1.12 ± 0.05% at day 35 of storage) and the crystallinity of the microparticles (>170 °C). The highest stability of PWO-C(HTE-C10)/SA suggests a specific location of HTE-C10 at the oil:water interface. The SA layer delayed the release of fatty acids during in vitro digestion. The incorporation of HTEs of medium chain length can be a suitable strategy to protect unsaturated oils encapsulated by spray-drying.

Stability of Bioactive Compounds in Olive-Pomace Oil at Frying Temperature and Incorporation into Fried Foods.

The stability of minor bioactive compounds in olive-pomace oils (OPOs) was evaluated at frying temperature under the conditions of a thermoxidation test. Bioactive compounds analyzed included squalene, tocopherols, sterols, triterpenic acids and alcohols, and aliphatic alcohols. In order to determine the amount of OPO bioactive compounds incorporated into foods after frying, three different kinds of frozen products were selected, i.e., pre-fried potatoes (French fries), pre-fried battered chicken nuggets, and chicken croquettes (breaded patties), and were used in discontinuous frying experiments. Results obtained in both the thermoxidation and frying studies showed high stability of triterpenic alcohols (erythrodiol and uvaol), oleanolic acid, and aliphatic alcohols, naturally present in OPOs. In all fried foods, the content of lipids increased after frying, as expected, although the extent of absorption of OPOs into fried foods and the exchange with food lipids depended on the food characteristics. Overall, frying with OPOs improved the nutritional properties of all products tested by increasing the level of oleic acid and by the incorporation of squalene, triterpenic acids and alcohols, and aliphatic alcohols, in significant quantities.

Performance of Olive-Pomace Oils in Discontinuous and Continuous Frying. Comparative Behavior with Sunflower Oils and High-Oleic Sunflower Oils.

Frying performance of olive-pomace oils (OPOs) as compared to sunflower oils (SOs) and high-oleic sunflower oils (HOSOs) was studied in discontinuous frying (DF) and continuous frying (CF) for the first time. DF is used in household, restaurants and frying outlets, while CF is used in the food industry. Oil alteration during frying was determined by measurements of polar compounds (PC) and polymers. Fried potatoes were analyzed for oil absorption and alteration, color, and evaluated in an acceptability test. Results for DF showed that all SOs reached 25% PC at the 9th frying operation (FO), whereas HOSOs did between the 17-18th FO and variable results were found for OPOs since initial levels of diacylglycerols were different. Rates of formation of PC or polymers were the lowest for OPOs, thus showing the best performance in DF. Specifically for PC, relative rates of formation were 1.00-1.11, 2.46-2.71 and 1.37-1.41 for OPOs, SOs and HOSOs respectively. In CF, OPOs and HOSOs behaved similarly and better than SOs, although none reached 25% PC after 40 FO. The good performance of OPOs can be attributed to the high monounsaturated-to-polyunsaturated ratio, in common with HOSOs, and the additional positive effect of minor compounds, especially ß-sitosterol and squalene.

Chemical Changes of Hydroperoxy-, Epoxy-, Keto- and Hydroxy-Model Lipids under Simulated Gastric Conditions.

Chemical changes occurring in dietary lipid oxidation compounds throughout the gastrointestinal tract are practically unknown. The first site for potential chemical modifications is the stomach due to the strong acidic conditions. In this study, model lipids representative of the most abundant groups of dietary oxidation compounds were subjected to in vitro gastric conditions. Thus, methyl linoleate hydroperoxides were used as representative of the major oxidation compounds formed in food storage at low and moderate temperatures. Methyl 9,10-epoxystearate, 12-oxostearate and 12-hydroxystearate were selected as model compounds bearing the oxygenated functional groups predominantly found in oxidation compounds formed at the high temperatures of frying. Analyses were performed using gas-liquid chromatography/flame ionization detection/mass spectrometry and high performance-liquid chromatography/ultraviolet detection. Losses of methyl 9,10-epoxystearate and linoleate hydroperoxides in the ranges 17.8-58.8% and 42.3-61.7% were found, respectively, whereas methyl 12-oxostearate and methyl 12-hydroxystearate remained unaltered. Although quantitative data of the compounds formed after digestion were not obtained, methyl 9,10-dihydroxystearate was detected after digestion of methyl 9,10-epoxystearate, and some major volatiles were detected after digestion of linoleate hydroperoxides. Overall, the results showed that significant modifications of dietary oxidized lipids occurred during gastric digestion and supported that the low pH of the gastric fluid played an important role.

Effect of consumer's decisions on acrylamide exposure during the preparation of French fries. Part 2: Color analysis.

Two observational tests were designed to investigate the influence of consumer decisions during the preparation of French fries from fresh potatoes on acrylamide formation. In both tests, color was of paramount importance to volunteers with regards to the decision to stop the frying process. CIE-Lab* color parameters and visual color assessments of French fries were associated with general acrylamide content and its classification according to the EU benchmark levels (BL, 500 µg/kg). Binary logistic regression analysis revealed that color parameter a* was the main factor in determining the probability of acrylamide content being above BL, regardless of the culinary practices applied. A cut-off of 0.855 for a* produced the greatest sensitivity (81.1%) and specificity (99.9%) for classifying samples with acceptable BL of acrylamide content. An increase of one unit of a* more than quadruple the risk of acrylamide content not falling within BL. When no external color reference was provided, volunteers misclassified 33.6% of fries as having a golden color. Harmonized criteria based on a reference color chart that indicates a golden color are necessary for producing fries with reduced acrylamide contents and, in this way, limit the risk of exposure to acrylamide in domestic settings.

Effect of consumer's decisions on acrylamide exposure during the preparation of French fries. part 1: Frying conditions.

Variability in home-cooking practices affects dietary exposure to acrylamide, limiting risk evaluation. Two observational tests (controlled and randomized) involving 127 volunteers was designed to investigate the influence of consumer decisions on acrylamide formation during the preparation of French fries. Consumer practices were recorded during pre-frying, frying and post-frying stages. Reducing sugar content, asparagine, moisture, acrylamide, moisture, weight loss and color were evaluated. In the controlled assay, mean acrylamide content was 508 µg/kg and volunteers took a mean frying time of 91.9 s (87.5-96.4, C.I. 95%). The narrow confidence interval of 8.9 s represented an increase of 120 µg/kg in the acrylamide content of the fried potato. Average acrylamide content in the randomized assay (215 µg/kg, 150-280 µg/kg, C.I. 95%) was significantly lower than in the controlled assay. Amongst the culinary practices applied for the potato variety evaluated, washing of the potato strips significantly reduced acrylamide content in French fries. The percentage of samples with acrylamide lower than the benchmark value (500 µg/kg) was 54% and 93% for the controlled and randomized assays, respectively. Estimated average dietary exposure to acrylamide from French fries in adults was 5.65 µg/day, which corresponds to a margin of exposure of 2105 for carcinogenicity.

Influence of the Location of Ascorbic Acid in Walnut Oil Spray-Dried Microparticles with Outer Layer on the Physical Characteristics and Oxidative Stability.

Purified walnut oil (PWO) microparticles with Capsul® (C, encapsulating agent), sodium alginate (SA) as outer layer and ascorbic acid (AA) as oxygen scavenger were obtained by spray drying using a three-fluid nozzle. AA was incorporated in the inner infeed (PWO-C(AA)/SA), in the outer infeed (PWO-C/SA(AA)) and in both infeed (PWO-C(AA)/SA(AA)). PWO-C(AA)/SA (4.56 h) and POW-C(AA)/SA(AA) (2.60 h) microparticles showed higher induction period than POW-C/SA(AA) (1.17 h), and lower formation of triacylglycerol dimers and polymers during storage (40 °C). Therefore, AA located in the inner infeed improved the oxidative stability of encapsulated PWO by removing the residual oxygen. AA in the SA outer layer did not improve the oxidative stability of encapsulated PWO since oxygen diffusion through the microparticles was limited and/or AA weakened the SA layer structure. The specific-location of AA (inner infeed) is a strategy to obtain stable spray-dried polyunsaturated oil-based microparticles for the design of foods enriched with omega-3 fatty acids.

RP-UHPLC-DAD-QTOF-MS As a Powerful Tool of Oleuropein and Ligstroside Characterization in Olive-Leaf Extract and Their Contribution to the Improved Performance of Refined Olive-Pomace Oil during Heating.

Since olive leaf is a potential source of phenolic fraction that is assumed to have good antioxidative effects, we purposed to add its extract to the refined olive-pomace oil during heating to increase its oxidative stability. RP-UHPLC-DAD-QTOF-MS was employed to characterize the phenolic fraction.The oil samples were evaluated by measuring the polymers and the polar compounds and thus detecting specific oxidized compounds. Using this approach, the results showed that incorporating olive leaf extract in refined oil significantly reduced the formation of polymers from 14.39% to 10.45% and the oxidation state by the variation of extinction ΔK from 3.02 to 2.29 during 20 h of heating compared to unenriched oil. This study has proven that the use of natural substances is an opportunity to extend the life of refined oils.

Acrylamide in French fries prepared at primary school canteens.

Children are one of the most exposed groups to dietary acrylamide with 'potato fried products' that account for up to half the total exposure to this contaminant. Acrylamide was measured in French fries prepared in 31 primary school canteens randomly recruited from different Spanish regions. The mean content was 329 µg kg-1 (from <20 to 4000 µg kg-1). French fries prepared from frozen par-fried potatoes reported a lower acrylamide content than those from fresh potatoes, 229 and 460 µg kg-1, respectively. Only 15.7% of samples were above the benchmark levels established by the EU Regulation 2017/2158 (500 µg kg-1). Significant differences were found according to the color of toasted (2274 µg kg-1), dark-golden (463 µg kg-1), golden (134 µg kg-1) and light-golden (52 µg kg-1) French fries. All the samples that were golden and light-golden showed acrylamide content below the threshold. The chromatic parameter a* was used as a rough classification of the French fries according to the benchmark level. Both educational initiatives intended for food operators and managerial-technical criteria that include the code of frying practices at public food service establishments should consider the golden color as the target for the end-point of frying. Acrylamide exposure will be reduced and, therefore, the risk linked to French fries consumption. This fact is especially relevant in establishments that prepare food for schoolchildren and would help to provide healthier diets, not only from a nutritional point of view but also from the reduction of chemical contaminants.

Influence of the Physical State of Spray-Dried Flavonoid-Inulin Microparticles on Oxidative Stability of Lipid Matrices.

The effect of the physical state of flavonoid-inulin microparticles (semi-crystalline/amorphous) on the oxidative stability of lipid matrices was studied. Epicatechin (E) and quercetin (Q) microparticles with inulin were formulated at two infeed temperatures (15 °C and 90 °C) by spray drying. X-ray diffraction analyses showed that flavonoid-inulin microparticles obtained at feed temperature of 15 °C were semi-crystalline (E-In-15, 61.2% and Q-In-15, 60%), whereas those at 90 °C were amorphous (Q-In-90, 1.73 and Q-In-90 2.30%). Semi-crystalline state of flavonoid-inulin microparticles enhanced the EE (68.8 and 67.8% for E and Q, respectively) compared to amorphous state (41.6 and 51.1% for E and Q, respectively). However, amorphous Q-microparticles showed the highest antioxidant activity both in methyl linoleate and sunflower oil, increasing the induction period and decreasing the polar compounds and polymer triglyceride formation during long-term oxidation study. Therefore, the physical state of spray-dried flavonoid-inulin microparticles may determine their antioxidant activity in lipid matrices.

Effect of spray-drying with organic solvents on the encapsulation, release and stability of fish oil.

Fish-oil (FO) was encapsulated with hydroxypropylcelullose (HPC) by conventional spray-drying with water (FO-water) and solvent spray-drying with ethanol (FO-EtOH), methanol (FO-MeOH) and acetone (FO-Acet) in order to study the effect of the solvent on the encapsulation efficiency (EE), microparticle properties and stability of FO during storage at 40 °C. Results showed that FO-Acet presented the highest EE of FO (92.0%), followed by FO-EtOH (80.4%), FO-MeOH (75.0%) and FO-water (71.1%). A decrease of the dielectric constant increased the EE of FO, promoting triglyceride-polymer interactions instead of oil-in-water emulsion retention. FO release profile in aqueous model was similar for all FO-microparticles, releasing only the surface FO, according to Higuchi model. Oxidative stability of FO significantly improved by spray-drying with MeOH, both in surface and encapsulated oil fractions. In conclusion, encapsulation of FO by solvent spray-drying can be proposed as an alternative technology for encapsulation of hydrophobic molecules.

Acrylamide content in French fries prepared in households: A pilot study in Spanish homes.

An observational cross-sectional pilot study in 73 Spanish households was conducted to evaluate the impact of consumer practices on the formation of acrylamide during the preparation of French fries from fresh potatoes applying one stage frying. 45.2% of samples presented acrylamide concentrations above the benchmark level for French fries (500 µg/kg). 6.9% of samples exceeded 2000 µg/kg and the 95th percentile was 2028 µg/kg. The median and average values were significantly higher than the EFSA report for this food category, suggesting that the total exposure to acrylamide by the population could be underestimated. In this randomised scenario of cooking practices, the content of reducing sugar and asparagine did not explain the acrylamide levels. However, the chromatic parameter a∗ of the fried potato was a powerful tool to classify the samples according to the acrylamide benchmark level regardless of the agronomical characteristics of the potato or the consumer practices.

Concentrates of triterpenic acids obtained from crude olive pomace oils: characterization and evaluation of their potential antioxidant activity.

BACKGROUND: Pentacyclic triterpenic acids (TA) are phytochemicals of increasing nutritional interest owing to their bioactive properties, such as anti-inflammatory, antitumoral, antihyperglycemic and hepatoprotective. Crude olive pomace oils constitute a non-exploited significant source of these compounds. In the present study, concentrates of TA were extracted and characterized from crude olive pomace oils that were obtained by centrifugation and subsequent solvent extraction, respectively. Specifically, the concentrates were obtained from the byproduct generated in the filtration of the oils. The solids were subjected to Soxhlet extractions with hexane to remove the residual oil and then with ethanol for the TA extraction. RESULTS: Concentrates containing 850-980 g kg-1 TA were isolated from the oils obtained by centrifugation, whereas those isolated from oils obtained by hexane extraction presented levels of TA that ranged from 510 to 900 g kg-1 . Oleanolic (OA) and maslinic (MA) acids were the TA found in the concentrates. The relative contents of OA and MA were, respectively, 30:70 (w/w) and 77:23 (w/w). All concentrates also presented phenolic compounds at levels of g kg-1 and displayed slight antioxidant properties. CONCLUSION: Concentrates of TA, containing MA and OA, can be readily obtained from a byproduct generated by filtration of crude olive pomace oils. Concentrates isolated from oils obtained by centrifugation were rich in MA, whereas those from oils extracted with hexane were rich in OA. The concentrates showed slight antioxidant properties that can be mainly attributed to the presence of phenolic compounds and not to TA. © 2018 Society of Chemical Industry.

Effectiveness of α-, γ- and δ-Tocopherol in a CLA-Rich Oil.

Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of octadecadienoic acid with conjugated double bounds. Positive health properties have been attributed to some isomers, such as anticarcinogenic activity, antiartherosclerotic effects and reduction of body fat gain. Hence, oils rich in CLA such as Tonalin(®) oil (TO), normally obtained through alkaline isomerization of safflower oil (SO), an oil rich in linoleic acid (LA), are currently used in functional foods. However, special care must be taken to protect them from oxidation to ensure the quality of the supplemented foods. The objective of this work was to evaluate the oxidation and effectiveness of different tocopherol homologues (α-, γ- and δ-), alone or in combination with synergists (ascorbyl palmitate and lecithin), in TO compared to SO at different conditions, ambient temperature (25 °C) and accelerated conditions in Rancimat (100 °C). The oils, the oils devoid of their antioxidants and the latter containing the antioxidants added were assayed. Results showed great differences between SO and TO in terms of formation of hydroperoxides and polymers and also in the effectiveness of tocopherols to delay oxidation. TO showed higher levels of polymerization and, in general, the effectiveness of tocopherol homologues, alone or in combination with synergists, was also lower in the TO.