The thermal oxidation evolution and relationship of unsaturated fatty acids and characteristic functional groups in blended oils with raspberry seed oil during deep-frying process by low field nuclear magnetic resonance and 1H nuclear magnetic resonance

Influence of beeswax-based fish oil oleogels on the mechanism of water and oil retention in Pacific white shrimp (Litopenaeus vannamei) meat emulsion gels: Filling, emulsification and phase transition

Oleogels have been used in the gelled surimi products to replace animal fats due to its structure characteristics. The effect of structure characteristics in fish oil oleogels on the mechanism of oil/water retention was investigated in meat emulsions. Beeswax assembly improved the oil and water retention. The unsaturation degree of fatty acids lowered the mobility of bound water, immobilized water as well as bound fat in the fish oil oleogel, but enhanced the mobility of free water and protons of unsaturated fatty acids. Beeswax addition and oil phase characteristics could enhance β-sheets, disulfide bonds and hydrophobic force to improve the viscoelasticity, gel strength and oil/water retention. Beeswax assembly facilitated the tight micro-sol network and filling effect, and high unsaturation degree promoted the emulsification effect, thus reducing phase transition temperature and juice loss. The study could lay the foundation for development of gelled shrimp meat products with EPA and DHA.

A sight of self-assembly mechanism in fish oil oleogels: Phase transition, crystal structure and non-covalent interaction

Fish oils contain ω-3 polyunsaturated fatty acids (PUFAs), but easily cause quality deterioration due to the oxidation. Beeswax-based oleogels could wrap fish oils by beeswax self-assembly. The phase transition, crystal structure and non-covalent interaction were investigated to reveal the self-assembly mechanism from the perspective of beeswax and oil phase characteristics. The results indicated that high unsaturation degree, PUFAs and beeswax additions promoted phase transition, SFC and stable crystal networks. The changes of crystal structures were ascribed to the polymorphism and polymorphic transition. β-Polymorphs could form crystal networks, and β'-polymorphs could influence the size of crystal chains or clusters as well as crystalline domains. Crystalline domain sizes affected crystal morphologies and network structures, including plate-like structures and multi-layer porous structures. UFAs could involve the beeswax self-assembly to change structure characteristics by van der Waals forces and π-π stacking. The OBC remained 100%, when beeswax additions reached more than 6%. Hence, beeswax additions, PUFA contents and unsaturation degree all influenced the self-assembly mechanism and adjusted the macroscopic properties of oleogels.

Influence of Seeds' Age and Clarification of Cold-Pressed Raspberry (Rubus idaeus L.) Oil on the DSC Oxidative Stability and Phase Transition Profiles

After cold-pressing, small particles of seed residue remain in raspberry seed oil (RSO), even after passing it through cold filtration. The removal of the remaining seed residue is rather an alternative option to improve the visual properties of RSO. This study investigated the influence that the seeds’ age (0, 10, 20 months) and clarification process after pressing has on the oxidative stability and phase transition of RSO by means of differential scanning calorimetry (DSC). The results proved that the oil centrifugation process reduces the DPPH radical scavenging activity and oxidative stability measured by p-anisidine value (p-AnV) and DSC oxidation induction time (OIT) at 120 °C of all RSO samples, regardless of the age of the seeds (p ≤ 0.05). No significant differences were observed on the DSC melting and crystallization properties at 1 °C/min after the oil clarification by centrifugation (p > 0.05). The storage time of raspberry seeds, i.e., 10 and 20 months after expiry date, influenced the quality deterioration of RSO, as measured by higher p-AnV, lower DPPH, and OIT values (p ≤ 0.05). The results presented provide new information about oil production processing, suggesting that producers should reconsider giving up the clarification process of oil, since it lowers all quality parameters.

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.

Sensitivity of Proton NMR Relaxation and Proton NMR Diffusion Measurements to Olive Oil Adulterations with Vegetable Oils

Olive oils and, in particular, extra-virgin olive oils (EVOOs) are one of the most frauded food. Among the different adulterations of EVOOs, the mixture of high-quality olive oils with vegetable oils is one of the most common in the market. The need for fast and cheap techniques able to detect extra-virgin olive oil adulterations was the main motivation for the present research work based on ¹H NMR relaxation and diffusion measurements. In particular, the ¹H NMR relaxation times, T₁ and T₂, measured at 2 and 100 MHz on about 60 EVOO samples produced in Italy are compared with those measured on four different vegetable oils, produced from macadamia nuts, linseeds, sunflower seeds, and soybeans. Self-diffusion coefficients on this set of olive oils and vegetable oil samples were measured by means of the ¹H NMR diffusion ordered spectroscopy (DOSY) technique, showing that, except for the macadamia oil, other vegetable oils are characterized by an average diffusion coefficient sensibly different from extra-virgin olive oils. Preliminary tests based on both NMR relaxation and diffusometry methods indicate that eventual adulterations of EVOO with linseed oil and macadamia oil are the easiest and the most difficult frauds to be detected, respectively.

Nutritional targeting modification of silkworm pupae oil catalyzed by a smart hydrogel immobilized lipase

To prepare a nutritional supplement using silkworm pupae oil (SPO) as a feedstock, a microfluidic reactor with a smart hydrogel immobilized lipase was first constructed to reduce the relative content of palmitic acid at sn-1,3 and improve the nutritional function. The effects of flow rate, reaction temperature, and substrate molar ratio were investigated. In vitro digestion and pH-stat models were employed to analyze the digestion feature after the modification of SPO, while HPLC-ELSD, zeta potential, DSC, and TGA were used to evaluate the nutritional function. The relative content of "OOO" and "OPO" type triglycerides was increased by 49.48% and 107.67%, and that of palmitic acid at sn-1,3 was decreased by 49.61% in 10 s. After the verification of the in vitro digestion model, the fatty acid release rate of the modified SPO was significantly improved by 22.07%, indicating the nutritional function improvement of SPO. Therefore, the nutritional function of SPO has been improved successfully by the application of a microchannel reactor with photo-immobilized lipase, which could set a reference for the utilization of insect oil resources.