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BACKGROUND: Blending Moringa oleifera oil (MOO) with other oils of recognized lower stability under prolonged frying results in oxidation delay. The present study aimed to detail the probable molecular interactions supporting these observations, using a small amount of MOO (20%) and sunflower oil (SFO; 80%) under domestic deep‐frying conditions (intermittent frying of fresh potatoes, 180 °C, 2 × 90 min day⁻¹, 5 days). RESULTS: Blending 20% MOO with SFO resulted in a significantly lower formation of polymers (

Aiming to distinguish the nutritional and safety impacts on consumer’s health of prolonged frying with vegetable oils rich in monounsaturated fatty acids (MUFA), namely peanut oil (PO), canola oil (CO) and extra virgin olive oil (EVOO), a domestic deep-frying assay using fresh potatoes was implemented (175 °C, 8 h per day, up to 28 h). Based on a total polar compounds (TPC) degradation limit of 25%, PO and CO enabled 18–20 h of frying, while EVOO allowed significantly higher frying hours (> 28 h). Despite the non-significant variations in oxidized triglycerides contents observed through time, and loss of all major antioxidants during the first 8 to 12 h of frying, PO showed statistically higher amounts of conjugated dienes (27 at 20 h; against 19 in CO and 17 in EVOO) and CO of anisidine value (252 at 20 h; against 209 in PO and 100 in EVOO), indicative of different oxidation patters. This was corroborated with the analysis of major volatiles, with PO and CO being statistically richer in alkenals and alkadienals, respectively. Therefore, despite the MUFA predominance, differences in their unsaturation profile impact on the type and amount of degradations products formed under prolonged frying and consequently on consumer’s health. As to EVOO use for prolonged frying, despite its increased resistance to oxidation and lower risk of formation of unhealthy volatiles, it loses its pool of natural bioactive compounds in the first hours of frying. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13197-018-3489-z) contains supplementary material, which is available to authorized users.

Two low‐fat “frying” alternatives to deep‐frying were tested using two domestic equipment (microwave grill and convective oven), with fresh potatoes and four different frying oils (sunflower, soybean, canola, and olive oil). Potatoes composition was compared concerning nutrients, bioactivity, and fat oxidation. Fat reduction achieved 80% on both methods, directly associated with a decrease in oil natural bioactive components (vitamin E, fatty acids) and degraded lipids (oxidized triglycerides, polymers, aldehydes, etc.). Both microwave grill and oven cooking preserved potatoes and oil health attributes better than deep‐frying, particularly ascorbic acid, tocopherols, and total phenolics. Additionally, a significantly lower formation of acrylamide (−55% microwave grill and −76% oven) and oxidized lipids (oxidized triglycerides and unsaturated aldehydes) was observed, with microwave receiving higher sensory scores than the convective oven. This work sustains the possibility of using domestic equipment (microwave grill and oven) as healthier “frying” alternatives to deep‐frying.

Fresh potatoes were intermittently deep-fried up to recommended limits (175 °C, 8 h/day, 28 h) in extra-virgin olive oil (EVOO), peanut oil (PO) and canola oil (CO), and compared for diverse chemical components and sensorial attributes, aiming to quantify the impact of prolonged frying on potatoes nutrients, and the potential alterations resulting from the use of different monounsaturated-rich oils. Independently of oil type, its degradation promotes time-dependent losses of important potato nutrients, as vitamin C. Regarding the monounsaturated-rich oils tested, potatoes fried in CO had more equilibrated fatty acid profiles, but higher amounts of aldehydes derived from PUFA oxidation, while in EVOO were enriched with phenolic compounds. Acrylamide amounts were not affected by oil type or frying hours. Sensory degradation was gradually perceived by the panellists, except in PO. Prolonged frying should not be studied only on the basis of oil degradation because, even if within regulated limits, it induces loss of important food compounds. The authors acknowledge the financial support from PRODER (Contract n° 53988), co-financed by FAEDER, and from project UID/QUI/50006/2013 – POCI/01/0145/FEDER/007265 with financial support from FCT/MEC through national funds, co-financed by FEDER, under the Partnership Agreement PT2020 and the PhD Grant—SFRH/BD/82285/2011 attributed to Carla S.P. Santos. Lucía Molina García also acknowledges the financial support from Campus de Excelencia Internacional Agroalimentario (ceiA3) and University of Jaén, from Spain.

The volatile fraction of three vegetable oils recommended for deep-frying due to their high MUFA:PUFA ratios, namely extra-virgin olive oil, peanut oil and canola oil, was compared before and after frying potatoes, with a particular focus on toxic volatiles. For the purpose, a headspace solid-phase-micro extraction technique coupled with gas chromatography and mass spectrometry was optimized, with semi-quantification achieved using two internal standards. Significant qualitative and quantitative differences were observed, both before and after frying. From a total of 51 compounds, aldehydes were the main group formed after deep-frying, their nature and abundance being highly associated with the initial fatty acid composition, particularly linoleic acid (r2 = −0.999, p ≤ 0.001). Globally, extra-virgin olive oil revealed fewer formations of unsaturated aldehydes, including toxic ones, and correlated with lower amounts of degradation indicators, as polar compounds (r2 = 0.998, p ≤ 0.001) and p-anisidine value (r2 = 0.991, p ≤ 0.001). Despite the similarities in total unsaturation degree between canola and peanut oils, the former presented lower amount of volatiles, including E,E-2,4-decadienal and acrolein, the more toxic ones. These results highlight for the pertinence of volatile analyses to evaluate and compare oil degradation under thermal and oxidative stress, while complementing other degradation indicators. Additionally, the optimized methodology allows a direct comparison of different oil matrices, supporting further developments into more general methods for volatiles quantification, enabling more efficient comparison of results between research teams. The authors acknowledge the financial support from PRODER (Contract No. 53989), co-financed by FAEDER, and from project UID/QUI/50006/2013-POCI/01/0145/FEDER/007265 with financial support from FCT/MEC through national funds, cofinanced by FEDER, under the Partnership Agreement PT2020 and the PhD Grant—SFRH/BD/82285/2011 attributed to CSPS. LMG also acknowledges the financial support from Campus de Excelencia Internacional Agroalimentario (ceiA3) and University of Jaén, from Spain.

A comparative study of deep-frying and air-frying was performed, using two commercial air-frying equipment's and four common frying oils − sunflower, soybean, canola, and olive oils. Fried potatoes were compared in terms of color, moisture, lipid composition and degradation indicators, tocopherols, total ascorbic acid, β-carotene, antioxidant activity, acrylamide, and sensory analysis. The results show that fried potatoes obtained by air-frying processes presented an average of 70% less fat, which leads to a reduction of 45 kcal per 100 g. Most chemical parameters were similar on both frying processes, including acrylamide content, or showed slightly better results with air-frying process, namely ascorbic acid amounts. However, incorporated fat was more damaged in deep-fried potatoes, with a significant increase on both p-anisidine and polar compounds. Despite the less significant differences observed in the two air-frying equipment's tested, lipid oxidation allowed their distinction, particularly p-anisidine that was higher in Airfryer than Actifry, independently of the oil type. All tested oils behaved similarly, and were mainly responsible for potatoes enrichment in tocopherols, phenolics, and β-carotene, but lower lipid oxidation was observed with olive oil. From the assessor's perspective, taste and odor qualities were more determinant for acceptability of fried potatoes than color. Practical applications: Air-frying has emerged in recent years as a healthier alternative to deep-frying. The direct comparison of deep-frying and air-frying technologies with different vegetables oils shows that air-frying process presents health benefits for consumers, with less fat ingestion and less fat oxidation, particularly when using olive oil, but also economic and ecological advantages due to reduced amount of oil used and no effluent after frying. A direct comparison of potatoes frying in two air-frying systems using different vegetable oils showed health benefits to the consumers when compared with deep-frying, both by the reduced amount of incorporated fat and lower fat degradation degree.