Development of amine-sensitive intelligent film with MIL-100(Fe) as function filler based on anthocyanins/pectin for monitoring chilled meat freshness.

To enhance the amine-sensitivity of intelligent films for accurate monitoring of chilled meat freshness, different additions (0, 1, 2, 3 wt%) of MIL-100(Fe) were incorporated into the matrix composed of anthocyanins (ANs) and pectin (P). Results indicated that the tensile strength, thermal stability, barrier performance and absorption capacity of the films with MIL-100(Fe) were improved significantly (p < 0.05). Especially, the film with 2 % MIL-100(Fe) exhibited the best performance due to its compact structure and the highest crystallinity. Additionally, adsorption isotherms of the films with MIL-100(Fe) were fitted on the Langmuir and the Freundlich isotherm, and adsorption kinetics were fitted on the pseudo-second-order model and Elovich model, respectively (R2 > 0.96), suggesting a combined mechanism of chemisorption and intraparticle diffusion. Besides, when the films were exposed in ammonia environment, they changed color from purple to blue-violet, finally to green. Ultimately, film with 2 % MIL-100(Fe) was used to monitor the chilled meat freshness, as expected, similar color variation was observed at three stages of meat freshness (fresh, sub-fresh, and spoiled), which enabled the accurate differentiation of meat freshness. Thus, films with MIL-100(Fe) demonstrated the potential to be amine-sensitive intelligent packaging for monitoring chilled meat freshness in real time.

Isolation, structural, biological activity and application of Gleditsia species seeds galactomannans.

Gleditsia fruits have been known as a valuable traditional Chinese herb for tens of centuries. Previous studies showed that the galactomannans are considered as one of the major bioactive components in Gleditsia fruits seeds (GSGs). Here, we systematically review the major studies of GSGs in recent years to promote their better understanding. The extraction methods of GSGs mainly include hot water extraction, microwave-assisted extraction, ultrasonic extraction, acid extraction, and alkali extraction. The analysis revealed that GGSs exhibited in the form of semi-flexible coils, and its molecular weight ranged from 0.018 × 103 to 2.778 × 103 KDa. GSGs are composed of various monosaccharide constituents such as mannose, galactose, glucose, and arabinose. In terms of pharmacological effects, GSGs exhibit excellent activity in antioxidation, hypoglycemic, hypolipidemic, anti-inflammation. Moreover, GSGs have excellent bioavailability, biocompatibility, and biodegradability, which make them used in food additives, food packaging, pharmaceutical field, industry and agriculture. Of cause, the shortcomings of the current research and the potential development and future research are also highlighted. We believe our work provides comprehensive knowledge and underpinnings for further research and development of GSGs.

Freeze-drying pretreatment of watermelon peel to improve the efficiency of pectin extraction: RSM optimization, extraction mechanism, and characterization.

This study assessed the processing parameters and mechanism of pectin extraction and pectin qualities from freeze-dried (FD) pretreatment watermelon peel. The optimal extraction conditions for the highest pectin yield (21.83 %) were a liquid/solid ratio (w/w) of 29, pH of 1.8, ultrasonic power of 573 W, and ultrasonic time of 43 min. Compared to hot-air dried (HD) method, the extraction of pectin from FD watermelon peel was facilitated by the increased cross-sectional areas of cells, transfer rate of extracting solution, mass transfer rate, and reduced rehydration time during the extraction. HD pectin (HDP) exhibited browning, whereas FD pectin (FDP) displayed bright brownish-yellow coloration. Furthermore, the L* value of pectin from FDP was significantly higher and a* and b* values were significantly lower than pectin from HDP (P < 0.05). Additionally, the moisture, ash and protein contents of FDP were significantly higher than those in HDP (P < 0.05). Structural characterization demonstrated FDP as a low-methoxy acetylated pectin, with significantly lower degree of methoxylation and molecular weight compared to that of HDP (P < 0.05). Besides, FDP demonstrated significantly superior emulsification performance compared to HDP (P < 0.05). These findings suggest FD as a potent, efficient, and time-saving technology for drying fresh watermelon peel for pectin preparation.

Active film preparation using pectin and polyphenols of watermelon peel and its applications for super-chilled storage of chilled mutton.

We investigated the effect of active packaging films prepared by pectin (WMP) and polyphenols (WME) obtained from watermelon peel on the quality of chilled mutton during super-chilled storage. The addition of WME created new chemical and hydrogen bonds in film. Furthermore, an appropriate amount of WME (≤1.5%) was evenly distributed throughout the film matrix, improving barrier properties, mechanical properties, thermal stability, and light transmittance of the film. An assessment of the meat quality showed that the pH, L*, b*, thiobarbituric acid reactive substances (TBARs), total volatile basic nitrogen (TVB-N), and total bacterial count (TCA) of super-chilled + film group were significantly lower, whereas shear force and a* value were significantly higher (P < 0.05) than other groups. The WMP/WME film has dense microstructure and excellent mechanical properties after storage. Pectin and polyphenols obtained from watermelon peel have good potential as a novel packaging material for chilled mutton during super-chilled storage.

A sensitive and quantitative immunochromatographic assay for simultaneous detection of three stimulant laxatives in slimming food.

Bisacodyl, sodium picosulfate and their metabolite bis-(p-hydroxyphenyl)-pyridyl-2-methane (BHPM) are clinically used to treat constipation. In this study, with the rational hapten design, a broad-specific and highly sensitive monoclonal antibody (mAb) was obtained with half of inhibitory concentrations of 0.16, 0.18 and 0.65 ng/mL for bisacodyl, sodium picosulfate and BHPM, respectively. Based on this mAb, a rapid and sensitive lateral flow immunochromatographic assay toward bisacodyl, sodium picosulfate and BHPM in slimming foods was developed. This method can qualitatively and quantitatively screen three stimulant laxatives with cut-off values of 3-6 ng/mL by naked eye and quantitative detection limits of 0.14-0.41 ng/mL by reader. The acceptable recoveries of spiked samples (78.00 %-120.12 %) and consistent results with liquid chromatography with tandem mass spectrometry (LC-MS/MS) in real sample detection confirmed the accuracy of the method. The established method provides a technique for multiplex, sensitive, fast, and on-site detection of three stimulant laxatives in slimming food.

Untargeted metabolomics by liquid chromatography-mass spectrometry for food authentication: A review.

Food fraud is currently a growing global concern with far-reaching consequences. Food authenticity attributes, including biological identity, geographical origin, agricultural production, and processing technology, are susceptible to food fraud. Metabolic markers and their corresponding authentication methods are considered as a promising choice for food authentication. However, few metabolic markers were available to develop robust analytical methods for food authentication in routine control. Untargeted metabolomics by liquid chromatography-mass spectrometry (LC-MS) is increasingly used to discover metabolic markers. This review summarizes the general workflow, recent applications, advantages, advances, limitations, and future needs of untargeted metabolomics by LC-MS for identifying metabolic markers in food authentication. In conclusion, untargeted metabolomics by LC-MS shows great efficiency to discover the metabolic markers for the authenticity assessment of biological identity, geographical origin, agricultural production, processing technology, freshness, cause of animals' death, and so on, through three main steps, namely, data acquisition, biomarker discovery, and biomarker validation. The application prospects of the selected markers by untargeted metabolomics require to be valued, and the selected markers need to be eventually applicable at targeted analysis assessing the authenticity of unknown food samples.

Updating insights into the rehydration of dairy-based powder and the achievement of functionality.

Dairy-based powder had considerable development in the recent decade. Meanwhile, the increased variety of dairy-based powder led to the complex difficulties of rehydrating dairy-based powder, which could be the poor wetting or dissolution of powder. To solve these various difficulties, previous studies investigated the rehydration of powder by mechanical and chemical methods on facilitating rehydration, while strategies were designed to improve the rate-limiting rehydration steps of different powder. In this review, special emphasis is paid to the surface and structure of the dairy-based powder, which was accountable for understanding rehydration and the rate-limiting step. Besides, the advantage and disadvantage of methods employed in rehydration were described and compared. The achievement of the powder functionality was finally discussed and correlated with the rehydration methods. It was found that the surface and structure of dairy-based powder were decided by the components and production of powder. Post-drying methods like agglomeration and coating can tailor the surface and structure of powder afterwards to obtain better rehydration. The merit of the mechanical method is that it can be applied to rehydrate dairy-based powder without any addition of chemicals. Regarding chemical methods, calcium chelation is proved to be an effective chemical in rehydration casein-based powder.

Integration of Untargeted and Pseudotargeted Metabolomics for Authentication of Three Shrimp Species Using UHPLC-Q-Orbitrap.

In this work, an untargeted and pseudotargeted metabolomics combination approach was used for authentication of three shrimp species (Litopenaeus vanmamei, Penaeus japonicus, and Penaeus monodon). The monophasic extraction-based untargeted metabolomics approach enabled comprehensive-coverage and high-throughput analysis of shrimp tissue and revealed 26 potential markers. The pseudotargeted metabolomics approach confirmed 21 markers (including 9 key markers), which realized at least putative identification. The 21 confirmed markers, as well as 9 key markers, were used to develop PLS-DA models, correctly classifying 60/60 testing samples. Furthermore, DD-SIMCA and PLS-DA models were integrated based on the 9 key markers, with 59/60 and 20/20 samples of the species that were involved and uninvolved in model training correctly classified. The results demonstrated the potential of this untargeted and pseudotargeted metabolomics combination approach for shrimp species authentication.

Effects of calcium chelation on the neutralization of milk protein isolate and casein micelle reassembling.

Rehydration in an alkaline solution has been shown to improve the rehydration behaviour of milk protein isolate (MPI). In this study, the focus is on citric acid neutralization of MPI powder dissolved in alkaline solution. The results showed that alkalization induced more negative zeta-potential compared to MPI control, reducing it from -22.4 mV to -32.6 mV. Neutralization had a relatively similar zeta-potential value as alkalized sample. Sodium carbonate addition increased pH and caused a consequential reduction of ionic calcium in aqueous phase and, neutralization caused a small increase in ionic calcium. Soluble aggregate of κ-casein protein and whey protein was suggested in alkalization and neutralization process by non-reducing SDS-PAGE. In addition, neutralization kept a stable colloidal particle size for pHs decreased to pH 9,8 and 7; however, alkalization and neutralization created casein aggregates of larger colloidal particle size than primary casein micelle in control MPI.

Short communication: Effects of nanofiltration and evaporation on the physiochemical properties of milk protein during processing of milk protein concentrate.

The aim of this work was to evaluate the effects of nanofiltration and evaporation concentration technologies on the physiochemical properties of milk protein concentrate (MPC) during processing. Skim milk, ultrafiltered milk, evaporated milk, nanofiltered milk, evaporated MPC, and nanofiltered MPC samples were collected at different processing stages. Chemical composition, microstructure of casein micelles, free sulfhydryl content, and surface hydrophobicity of the samples were determined. The insolubility index of MPC was also determined. Casein micelles aggregated compactly after evaporation while surface hydrophobicity increased and free sulfhydryl content decreased in evaporated milk compared with skim milk. However, the microstructure of the casein micelles was relatively undisturbed after nanofiltration, with reduced surface hydrophobicity and free sulfhydryl content. No significant difference was found in chemical composition between the 2 MPC preparations: approximately 61.40% protein and 28.49% lactose. In addition, the particulate microstructures of both MPC were similar. However, the insolubility index of evaporated MPC was significantly (0.58mL) higher than that of nanofiltered MPC. Nanofiltration may be an effective way to improve the solubility of MPC products.