Search

BACKGROUND Phospholipids, the main lipid component in marine shellfish, mainly comprise glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE). GPC and GPE in marine shellfish, especially scallop, carry n‐3 long‐chain polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), although different types of glycerophospholipids (GP) have different health benefits on human health. Moreover, different GP subclasses such as GPC and GPE have different oxidative susceptibilities in complex food systems. The present study compared the oxidative susceptibilities of GPC and GPE in dried scallop during storage by high‐performance liquid chromatography‐tandem mass spectrometry and kinetic models, and also investigated the effects of natural phenolic antioxidant on their susceptibilities. RESULTS: The results showed that GPC and GPE molecular species (carrying EPA or DHA) contents in samples continuously reduced during storage at two different temperatures. The first‐order kinetic model better reflected the changes of GPC and GPE molecular species (carrying EPA or DHA) in samples than the zero‐order kinetic model during storage. According to the oxidation rate (k) obtained from first‐order kinetic models, GPE possessed a greater oxidation rate than GPC during storage. Moreover, the results showed that antioxidants of bamboo leaves (AOB, polar polyphenolic antioxidants) significantly decreased the oxidation rates of GPC and GPE molecular species (carrying EPA or DHA) in samples during storage, and GPC could be more effectively protected by AOB compared to GPE. CONCLUSION: The present study provides a practical method for accurately evaluating the oxidative susceptibility of different phospholipid classes in complex food systems. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Fresh shrimp (Penaeus vannamei) deteriorates easily and the drying process is an important processing method for prolonging the shelf life of shrimp. The traditional drying method is hot‐air‐drying (HD), which can cause some problems such as nutrient loss, discoloration and lipid oxidation. In recent years, freeze‐drying (FD) has been popular for removing moisture from food at lower temperatures, maintaining the structure of raw materials, and improving storage stability of products. In the present study, the effects of HD and FD on lipid and color of P. vannamei and the mechanisms involved were investigated. RESULTS: FD caused less lipid oxidation compared to HD; consequently, FD‐processed shrimps had lower levels of primary and secondary oxidation products, as well as acid value, and higher contents of triacylglycerol, phosphatidylcholine, phosphatidylethanolamine, eicosapentaenoic acid and docosahexaenoic acid compared to HD‐processed samples. Lipase and lipoxygenase played a role in the oxidation and hydrolysis of lipids during drying process. FD‐processed shrimps had lower yellowness value and chromatic aberrations but a higher whiteness value compared to HD‐processed samples. Correlation analysis showed that lipid oxidation, astaxanthin degradation and the Maillard reaction contributed to the changes of color. Principal component analysis indicated that FD caused less deterioration in quality compared to HD. CONCLUSION: In the present study, FD is recommended for preserving shrimp color and lipid nutrition in terms of lipid oxidation control. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The optimum combination of antioxidants used for stabilization of flaxseed oil and extension of its shelf life was examined. To achieve this goal, based on different antioxidant mechanisms, a combination of four types of antioxidants including tocopherol, ascorbyl palmitate (AP), phytic acid (PA), and a source of polyphenol (antioxidant of bamboo leaves (AOB), rosemary extract (RE), tea polyphenols extract (TP), and tea polyphenol palmitate (TPP)) were added to flaxseed oil. The effects were monitored using peroxide value (POV), thiobarbituric acid‐reactive substances (TBARS), free radicals, and Rancimat induction time (RIT) of flaxseed oil during accelerated storage. Flaxseed oil containing 80 mg/kg tocopherol, 40 mg/kg AP, 40 mg/kg PA, and 240 mg/kg TPP was found to be more stable to oxidation than other samples and had 3.22‐fold longer shelf life than that of the control flaxseed oil. Practical applications: Due to its high concentration of alpha‐linolenic acid, flaxseed oil is prone to oxidation. To improve the oxidative stability of flaxseed oil and prolonging its shelf life, the optimum formulation and ratio of mixtures of antioxidants with different antioxidant mechanisms were studied. Our results indicated that the flaxseed oil containing 80 mg/kg tocopherol, 40 mg/kg AP, 40 mg/kg PA, and 240 mg/kg TPP was very stable to oxidation. And the shelf life of the flaxseed oil containing this optimum mixture of antioxidants was 3.22‐fold longer than that of the control flaxseed oil. Therefore, adding the optimum mixture of antioxidants will help to produce the flaxseed oil products with better oxidative stability for commercial development. [ABSTRACT FROM AUTHOR]

In the present paper, Fourier transform infrared spectrometer was applied to gain the infrared spectra of Hypnum fertile Sendtn. samples with different concentration of Cd2+ for 7 days to study the changes in chemical components, and some physiological characteristics such as malondialdehyde (MDA), solubility sugar (SS) and solubility protein (Pr) were also studied. Malondialdehyde and solubility sugar were measured by anthrone colorimetry and solubility protein was measured by brilliant blue and commassie dye. The results showed that with the enhancement of Cd2+ concentration, the contents of solubility sugar and solubility protein were enhanced at first and then decreased. However, it was just the opposite for the content of malondialdehyde. Based on the indices of wave number-absorbance, the infrared spectra of samples with different concentration of Cd2+ were compared in terms of changes in the physiological characteristics. The two bands at 2 920 and 2 855 cm(-1) in the CH stretching region (3 000-2 800 cm(-1)) of the spectra denote the asymmetric and symmetric lipid CH2 stretching vibrations, whose band height's variety was related to the change in malondialdehyde content in plant. The distinctive amide-I band at 1 635 cm(-1) and amide-II band at 1 545 cm(-1) arise from endogenous proteins. In the region below 1 500 cm(-1), a variety of characteristic IR group frequencies can be observed that are difficult to assign but the shape of the spectra in this region is characteristic and can be used as a "finger print" of the tissue. The band at 1 036 cm(-1)-C-O, -C-C or CH stretching region of the spectra denotes the carbohydrate related to the content of solubility sugar. The results showed that there was good correspondence between the changes in the physiological characteristics and the changes of samples based on the indices of wave number-absorbance of FTIR spectra, and the FTIR was more sensitive and convenient. Therefore, Fourier transform infrared spectrometry can be accepted as a fast and effective method to study bryophytes for monitoring the pollution degree of heavy metal in environment.