正相高效液相色谱法同时测定肉制品中4 种羟基十八碳二烯酸异构体的含量

为建立同时测定肉制品中13-羟基-9Z,11E-十八碳二烯酸（13-hydroxy-9Z,11E-octadecadienoic acid，13-Z,E-HODE）、13-羟基-9E,11E-十八碳二烯酸（13-hydroxy-9E,11E-octadecadienoic acid，13-E,E-HODE）、9-羟基-10Z,12E-十八碳二烯酸（9-hydroxy-10Z,12E-octadecadienoic acid，9-Z,E-HODE）、9-羟基-10E,12E-十八碳二烯酸（9-hydroxy-10E,12E-octadecadienoic acid，9-E,E-HODE）的高效液相色谱检测方法，肉制品中的13-Z,E-HODE、13-E,E-HODE、9-Z,E-HODE和9-E,E-HODE经甲醇提取、采用Sep-Pak C18柱净化浓缩后，在硅胶柱Absolute SiO2（250 mm×4.6 mm，5 μm）上以正己烷-异丙醇-乙酸（98.3∶1.6∶0.1，V/V）为流动相进行分离，选用二极管阵列检测器在234 nm进行测定。结果表明，13-Z,E-HODE、13-E,E-HODE、9-Z,E-HODE和9-E,E-HODE分别在质量浓度为0.5～20.0、0.25～10.0、0.75～12.5 μg/mL和0.5～7.5 μg/mL的范围内线性关系良好（R2分别为0.999 4、0.999 2、0.999 2、0.999 6），检出限分别为0.075、0.035、0.090、0.060 μg/g，定量限分别为0.25、0.12、0.32、0.20 μg/g，不同添加水平的平均回收率分别为89.03%、89.03%、89.33%、87.93%。对18 种肉制品含量分析表明，所有样本都含有13-Z,E-HODE、13-E,E-HODE、9-Z,E-HODE和9-E,E-HODE，含量分别为1.73～9.10、0.56～5.79、2.37～11.02、0.78～5.82 μg/g。综上，建立的检测方法快捷、准确、重复性好，可用于同时测定肉制品中13-Z,E-HODE、13-E,E-HODE、9-Z,E-HODE和9-E,E-HODE的含量。     

Lipid Composition and State of Oxidation of Fortified Infant Flours in Low‐Income Countries Are Not Optimal and Strongly Affected by the Time of Storage

Food fortification is widely used to address the public health problem of nutrient deficiencies. This study's purpose is to assess the lipid profile and nutritional quality of 13 fortified infant flours (FI) collected “in the field” in Africa and Asia after different periods of storage. The lipid content, fatty acid profiles, lipophilic vitamin content, and lipid oxidation state (peroxide values, secondary oxidation products) are determined. Mycotoxins and packaging materials are also characterized. The lipid content averages 9.1 ± 3.5 g/100 g. Fatty acid profiles are dominated by linoleic (43.3 ± 8.8%), oleic (29.5 ± 7.4%), and palmitic acid (17.8 ± 6.7%) and result in an average ω6/ω3 ratio of 12.2 ± 5.9 but with high values for some FI. Very high overages in vitamins A, D, and E are observed in products stored for short periods (1–6 months), whereas FI stored for more than 12 months has insufficient vitamin content. Lipid oxidation is acceptable but for six products presenting excessive peroxide values. Most products are contaminated by low amounts of mycotoxins but only two FI do not abide by the regulation. A strong correlation between peroxide values, hexanal content, and time of storage is observed. Practical Applications: The expiration dates for FI commercialized in low‐income countries should be shortened from 36 to 12 months so as to guarantee their nutritional quality of these functional foods and to abide by the fortified infant flour legislation. Indeed, FI quality significantly decreases over time of storage. The use of high barrier packaging materials must be generalized, although it is a necessary criterion but not sufficient to ensure the long‐term stability of FI. Special attention should be given to reduce lipophilic vitamin overages and to improve their lipid profile, especially the ω6/ω3 ratio, which has to be lower than 15.     

Effects of gamma irradiation dose and short-term storage on phytochemicals,antioxidants, and textural properties of boiled ‘Tainan 9’ peanuts

Boiled peanuts are preferable as a ready-to-eat healthy snack; however, gamma irradiation as a postharvest treatment of raw peanuts may induce unfavourable food components. Hence, the phytochemical, antioxidant, and the texture of boiled ‘Tainan 9’ peanuts pretreated with gamma irradiation (0, 2.5, 5, and 10 kGy) and stored at 29 ± 2 °C for up to 180 days were investigated. Both gamma irradiation and storage time contributed to testa darkening in raw peanuts. In boiled irradiated products, irradiation doses and storage time affected the moisture content (MC), total proteins, total oil, total soluble sugars, and antioxidant capacity (P ≤ 0.05). Total phenolic and flavonoid contents showed an increase at days 90 and decreased at days 180 across all treatments. A positive correlation was observed among ferric reducing antioxidant power (FRAP), total phenolics, and total flavonoids. Gamma irradiation at 10 kGy led to increase of peroxide value (PV) (P ≤ 0.05), but malondialdehyde (MDA) content was unaffected. Textural properties of boiled irradiated peanuts were soft. As a result, gamma irradiation at 5 kGy is recommended for postharvest treatment of raw peanuts with subsequent storage up to 180 days to obtain the eating quality of boiled peanuts with good phytochemicals and antioxidant properties, which is a challenge for food industry.     

Changes in lipid profiles and volatile compounds of shrimp (Penaeus vannamei) submitted to different cooking methods

Herein, the effect of three common cooking methods (boiling, baking and microwaving) on lipids and volatile compounds in shrimp (Penaeus vannamei) was assessed. The results revealed that contents of phospholipid, triglyceride, cholesterol and free fatty acids in the cooked shrimp significantly declined when compared to the raw shrimp. And these decreases occurred especially in the boiling and microwaving treatment. Among free fatty acids, the contents of palmitic acid (C_16:0), oleic acid (C_18:1n9c) and linoleic acid (C_18:2n6c) also decreased greatly in the boiled and microwaved shrimp, while EPA and DHA enhanced in each cooked group (P < 0.05). Furthermore, microwaved samples exhibited higher levels of oxidation parameters, such as acid value (AV) and thiobarbituric acid-reactive substances (TBARS). For volatile compounds, a total of 31 volatile compounds were detected by GC-IMS, and these contents increased after cooking. Aliphatic volatile compounds, including 1-octen-3-one, pentane-1-ol, 1-propanol, octanal, heptanal, pentanal and hexanal, were main flavour contributors in cooked shrimp, with higher contents observed in microwaved shrimp. In addition, the correlation analysis showed that linoleic acid was a substrate for 15 volatile compounds of cooked shrimp meat. These results indicate that microwave cooking exerts more influences on lipid profiles in shrimp and consequently caused more volatile compounds.     

Influence of different solid lipids on the properties of a novel nanostructured lipid carrier containing Antarctic krill oil

This study aimed to investigate the effect of solid lipids (lauric acid (LAU), myristic acid (MYR), stearic acid (STE), glycerol monostearate (GMS), glycerol 1,3-distearate (GDS), glycerol tristearate (GTS), glycerol trimyristate (GTM) and glycerol trilaurate (GTL)) on the characteristics of novel nanostructured lipid carrier (NLC) containing Antarctic krill oil through ultrasound. The fatty acids (LAU, MYR, STE and GMS) were unsuitable solid lipid materials, as apparent stratification was quickly observed during the NLC preparation. NLCs were successfully prepared using GTS, GTM, GTL and GDS. The zeta potential of all NLCs exceeded −30 mV indicating good uniformity and stability. These NLCs appeared spherical or oval. Differential calorimetry and X-ray diffraction analysis revealed these NLCs formed imperfect crystals. As the carbon chain length of triglycerides increased from C₁₂ to C₁₈, the particle size of NLCs increased from 235.8 ± 2.3 nm to 340.5 ± 2.2 nm, the degree of recrystallisation increased from 39.06% to 49.99%, while the EPA encapsulation efficiency decreased from 88.72 ± 0.47% to 72.86 ± 1.06%. NLC prepared with GDS had the smallest particle size (112.4 ± 0.4 nm), the lowest recrystallisation and the highest EPA encapsulation efficiency (>99%). GDS was the most suitable to prepare high encapsulate efficiency krill oil-loaded NLC.     

Modification of chitosan using hydrogen peroxide and ascorbic acid and its physicochemical properties including water solubility,oil entrapment and in vitro lipase activity

Chitosan was modified using H₂O₂ and ascorbic acid with different incubation temperatures (4–40 °C). The properties of modified chitosan, including its oil entrapment ability, water solubility and the lipase-resistant activities, using in vitro intestine model system were determined. Nuclear magnetic resonance analysis showed that ascorbic acid was bound to modified chitosan. All of the modified chitosan from 4 to 40 °C demonstrated improved water solubility (even in pH 7) compared to non-modified chitosan, which was only soluble at pH 4. Modified chitosan from 4 °C exhibited 27.40% of oil entrapment ability which was approximately four times higher than 6.87% of non-modified chitosan. Modified chitosan from 4 and 40 °C had increased resistance against lipase activity compared to other biopolymers, including beeswax, carnauba wax and non-modified chitosan. Modified chitosan could be used as a new food ingredient due to their high water solubility, oil-entrapping ability and resisting lipase activity.