Xiuzhu Yu

Novel method for the producing area identification of Zhongning Goji berries by electronic nose

High-quality Zhongning Goji berries (ZNG) are illegally adulterated in the market by adding non-ZNG (NZNG). An accurate, rapid, and effective approach for the producing area identification of ZNG is needed to protect the geographical indications of Goji berry products and to ensure fair trade. Samples from different regions were collected and their odors were detected by an electronic nose (E-nose). Principal component analysis (PCA), cluster analysis (CA), and linear discriminant analysis (LDA) were employed to build identification models. The E-nose models were further verified by gas chromatography-mass spectrometry (GC-MS). The identification rates of the PCA, CA, and LDA models were 91.0%, 98.9%, and 100%, respectively. The PCA and CA models presented good results, and the LDA model showed optimum performance. These conditions indicate the feasibility of using the E-nose technique for ZNG identification. GC-MS analysis revealed differences and similarities in total ion current chromatograms between ZNG and NZNG.

Direct FTIR analysis of isolated trans fatty acids in edible oils using disposable polyethylene film

A new transmission-based Fourier transform infrared (FTIR) spectroscopy method has been developed to determine trans fatty acids (TFA) content in edible oils using disposable polyethylene (PE) film as a spectral acquisition accessory. Calibration standards were devised by gravimetrically adding TFA to TFA-free oil. The response was measured at 990-945 cm(-1) against the baseline. A linear relationship between the areas in the spectral regions 1670-1625 cm(-1) and 990-945 cm(-1) in TFA-free oil samples was established to compensate for interference due to underlying triacylglycerol absorptions in the trans measurement region (990-945 cm(-1)). Subsequently, the area measured at 990-945 cm(-1) was corrected for interference, using the linear equation obtained, to determine TFA content. Results indicated that the PE film-based FTIR method for analyzing TFA content in edible oils was simple and rapid, and could be used effectively as an alternative to gas chromatography and mass spectrometry methods.

A novel method to determine total sugar of Goji berry using FT-NIR spectroscopy with effective wavelength selection

ABSTRACT This study investigated the feasibility of determining the content of Goji berry total sugar (GBTS) through Fourier transform near-infrared (FT-NIR) spectroscopy combined with chemometrics. A total of 114 Goji berry samples from different regions in China were scanned with a FT-NIR reflectance spectroscopic system. X-loading weights and correlation coefficients were utilised to identify the most influential wavelength after the selection of spectra processing methods. Partial least squares regression was applied to build models, and paired t test was used for external validation. The model with raw spectra after pre-treatment with Norris gap derivatives and effective wavelength of 8700–4000 cm−1, which were determined by the correlation coefficients, exhibited the best predicative ability. In addition, the determination coefficients (R2) of calibration validation set were both greater than 0.9 when principal component number was 6. The model presents good performance, with root mean square errors (RMSE) of 0.406 and 0.695 for the prediction of calibration validation set, relatively. The use of FT-NIR spectroscopy to implement quick determination of GBTS is thus feasible.

Efficient Salt-aided Aqueous Extraction of Bitter Almond Oil

BACKGROUND Salt-aided aqueous extraction (SAAE) is an inexpensive and environmentally friendly method of oil extraction that is influenced by many factors. In the present study, we investigated the effect of SAAE on bitter almond oil yield. RESULTS This study used sodium bicarbonate solution as extraction solvent and the optimal extraction parameters predicted by Box-Behnken design (i.e., concentration of sodium bicarbonate, 0.4 mol L-1 ; solvent-to-sample ratio, 5:1; extraction temperature, 84 °C; extraction time, 60 min), for oil recovery of 90.9%. The physiochemical characteristics of the extracted oil suggest that the quality was similar to that of the aqueous enzymatic extracted oil. Moreover, the content of hydrocyanic acid (HCN) in bitter almond oil was found to be less than 5 mg kg-1 , which was lower compared to that obtained by other reported methods. Results of microanalysis indicated that SAAE led to significant improvement in oil yield by allowing the release of oil and decreasing the emulsion fraction. Therefore, extraction of bitter almond oil by SAAE is feasible. CONCLUSION These results demonstrate that extraction of bitter almond oil by SAAE based on the salt effect is feasible on a laboratory scale.

Simple Synthesis Hydrogenated Castor Oil Fatty Amide Wax and Its Coating Characterization

A simple method for incorporating amine groups in hydrogenated castor oil (HCO) to produce wax for beeswax or carnauba wax substitution in packaging and coating was developed. From the conversion rate of the products, HCO was reacted with ethanolamine at 150°C for 5 h, and the molar ratio of HCO and ethanolamine was 1:4. The hardness of the final product was seven times higher than that of beeswax, the cohesiveness of the final product was 1.3 times higher than that of beeswax and approximately one half of that of carnauba wax, and the melting point of the final product is 98°C. The Fourier transform Infrared spectroscopy showed that the amide groups were incorporated to form the amide products. In coating application, the results showed that the force of the final product coating cardboard was higher than that of beeswax and paraffin wax and less than that of carnauba wax. After 24 h soaking, the compression forces were decreased. HCO fatty acid wax can be an alternative wax for carnauba wax and beeswax in coating applications.

Monitoring oxidative stability and changes in key volatile compounds in edible oils during ambient storage through HS-SPME/GC–MS

ABSTRACT Headspace solid-phase microextraction/gas chromatography–mass spectrometry (HS-SPME/GC–MS) analysis combined with ‘relative odour activity value (ROAV)’ was used to monitor changes in key volatile compounds in peanut oil, soybean oil, rapeseed oil, and linseed oil during ambient storage. Volatile composition and oxidation process were compared among edible oil samples. The differences in the volatile contents of edible oils led to their characteristic flavour. Aldehydes featured a relatively high content and low odour threshold and mainly contributed to the flavour of edible oils. The key flavour compounds included pentanal, hexanal, octanal, nonanal, trans-2-heptenal, and benzaldehyde, which are important oxidative degradation products of oleic acid and linoleic acid. The formation of key volatile oxidation compounds was affected by different oxidation processes during ambient storage. Certain aldehydes increased with oxidation level, whereas other aldehydes initially increased then decreased. Correlation analysis showed that the concentrations of several volatile compounds progressively increased during oxidation. The key volatile oxidation compounds formed during oil storage at ambient temperature are partly different from those generated at high temperatures. Volatile oxidation compounds can be a marker for monitoring the oxidation degree of edible oils during ambient storage.

A rapid method for evaluating the edible oil oxidative stability during ambient storage by FTIR spectroscopy using a mesh cell

A rapid method for evaluating the edible oil oxidative stability during ambient storage was established by Fourier transform infrared (FTIR) procedures, using a mesh cell as the spectral acquisition accessory. The prepared oil samples were exposed to visible light at ambient temperature (23 ± 2 °C), and the oxidative stability of edible oils was predicted by comparing the time when the peroxide value (PV) reached 20 and 100 meq. kg−1 by using the mesh cell-based oxidation method (MCOM) and bulk oxidation. The results indicated that the MCOM is 2.6 to 4.2 times faster than the oxidized oils in bulk when the PV reached 20 and 100 meq. kg−1, respectively. The oxidation changes in some functional groups can be monitored in real time during ambient storage using the mesh cell-based FTIR technique. Compared with traditional oxidation methods, the use of the mesh cell-based FTIR technique provides a simple, practical, and rapid means for evaluating the oxidative stability of edible oils during ambient storage.

Efficient Detection of Edible Oils Adulterated with Used Frying Oils through PE-film-based FTIR Spectroscopy Combined with DA and PLS

Edible oil adulteration has been a considerable problem worldwide, and rapid detection methods should be established. In this study, a validation method for edible oil adulterated with used frying oil (UFO) was introduced through Fourier transform infrared (FTIR) spectroscopy. The spectral region of 6000-400 cm-1 was determined through FTIR by using a disposable polyethylene film, and absorption profiles at 1550-650 cm-1 region could be used for detection analysis. A qualitative analysis model was established through discriminant analysis, and edible oil adulteration with more than 1% content of UFO could be qualitatively analyzed. A quantitative analysis model was also created through partial least squares regression. When the actual value was more than 1.5%, the predicted and actual values showed good linear correlation. FTIR coupled with chemometric analysis is a useful tool to detect edible oil adulteration.

An Improved Method for Determination of Cyanide Content in Bitter Almond Oil

An improved colorimetric method for determination of cyanide content in bitter almond oil was developed. The optimal determination parameters were as follows: volume ratio of hydrochloric acid to bitter almond oil (v/v), 1.5:1; holding time for hydrolysis, 120 min; and volume ratio of distillation solution to bitter almond oil (v/v), 8:1. Analytical results showed that the relative standard deviations (SDs) of determinations were less than 10%, which satisfies the test requirements. The results of high-performance liquid chromatography and measurements exhibited a significant correlation (R = 0.9888, SD = 0.2015). Therefore, the improved colorimetric method can be used to determine cyanide content in bitter almond oil.

Application of Fourier Transform Infrared Spectroscopy for the Quality and Safety Analysis of Fats and Oils: A Review

Abstract Fats and oils are essential food components. Their quality and safety pose major concerns for consumers and food producers because of factors such as oxidation and rancidity, excessive levels of trans fatty acid (TFA), and widespread adulteration. Thus, a rapid and easy-to-use technique must be exploited for quality parameter evaluation and monitoring to ensure the edibility, safety, and quality of fats and oils. In the last decades, Fourier transform infrared (FTIR) spectroscopy has shown great potential in analyzing fats and oils given its speed and simplicity. FTIR-based analytical techniques for common intrinsic quality parameters, including peroxide value, free fatty acid, moisture, TFA, iodine value, as well as oxidation stability, adulteration, and classification of various fats and oils, are summarized in this review. The advantages and disadvantages of selected infrared spectral accessories and sample preparation and spectral processing methods are highlighted. The prospects and reformative aspects for future application of the FTIR technique in the field of fats and oils are also discussed. This review may serve as a basis for applying FTIR not only in future research but also in the fat and oil industries.