Analysis of Volatile Organic Compounds in Milk during Heat Treatment Based on E-Nose, E-Tongue and HS-SPME-GC-MS.

Volatile organic compounds (VOCs) make up milk flavor and are essential attributes for consumers to evaluate milk quality. In order to investigate the influence of heat treatment on the VOCs of milk, electronic nose (E-nose), electronic tongue (E-tongue) and headspace solid-phase microextraction (HS-SPME)-gas chromatography-mass spectrometry (GC-MS) technology were used to evaluate the changes in VOCs in milk during 65 °C heat treatment and 135 °C heat treatment. The E-nose revealed differences in the overall flavor of milk, and the overall flavor performance of milk after heat treatment at 65 °C for 30 min is similar to that of raw milk, which can maximize the preservation of the original taste of milk. However, both were significantly different to the 135 °C-treated milk. The E-tongue results showed that the different processing techniques significantly affected taste presentation. In terms of taste performance, the sweetness of raw milk was more prominent, the saltiness of milk treated at 65 °C was more prominent, and the bitterness of milk treated at 135 °C was more prominent. The results of HS-SPME-GC-MS showed that a total of 43 VOCs were identified in the three types of milk-5 aldehydes, 8 alcohols, 4 ketones, 3 esters, 13 acids, 8 hydrocarbons, 1 nitrogenous compound, and 1 phenol. The amount of acid compounds was dramatically reduced as the heat treatment temperature rose, while ketones, esters, and hydrocarbons were encouraged to accumulate instead. Furfural, 2-heptanone, 2-undecanone, 2-furanmethanol, pentanoic acid ethyl ester, 5-octanolide, and 4,7-dimethyl-undecane can be used as the characteristic VOCs of milk treated at 135 °C. Our study provides new evidence for differences in VOCs produced during milk processing and insights into quality control during milk production.

Transcriptomic and proteomic profiling reveals the intestinal immunotoxicity induced by aflatoxin M1 and ochratoxin A.

Mycotoxins-contaminated milk could threaten human health; therefore, it is necessary to demonstrate the toxicological effect of mycotoxins in milk. Most recently, researchers have paid more attention to the immunotoxic effects of the individual cereal-contaminating mycotoxins, namely, zearalenone and deoxynivalenol. However, there is scant information about the intestinal immunotoxicity of aflatoxin M1 (AFM1), let alone that of a combination of AFM1 and ochratoxin A (OTA), which often co-occur in milk. To reveal the inflammatory response caused by these mycotoxins, expression of inflammation-related genes in differentiated Caco-2 cells was analyzed, demonstrating a synergistic effect of the mixture of AFM1 (4 µg/mL) and OTA (4 µg/mL). Integrative transcriptomic and proteomic analyses were also performed. A cross-omics analysis identified several mechanisms underlying this synergy: (i) compared with stimulation with either compound alone, combined use resulted in stronger induction of proteins involved in immunity-related pathways; (ii) combination of the two agents targeted different points in the same pathways; and (iii) combination of the two agents activated specific inflammation-related pathways. These results suggested that combined use of AFM1 and OTA might exacerbate intestinal inflammation, indicating that regulatory authorities should pay more attention to food contamination by multiple mycotoxins when performing risk assessments.

Enantioselective synthesis of a chiral coordination polymer with circularly polarized visible laser.

Circular dichroism is known to be the feature of a chiral agent which has inspired scientist to study the interesting phenomena of circularly polarized light (CPL) modulated molecular chirality. Although several organic molecules or assemblies have been found to be CPL-responsive, the influence of CPL on the assembly of chiral coordination compounds remains unknown. Herein, a chiral coordination polymer, which is constructed from achiral agents, was used to study the CPL-induced enantioselective synthesis. By irradiation with either left-handed or right-handed CPL during the reaction and crystallization, enantiomeric excesses of the crystalline product were obtained. Left-handed CPL resulted in crystals with a left-handed helical structure, and right-handed CPL led to crystals with a right-handed helical structure. It is exciting that the absolute asymmetric synthesis of a chiral coordination polymer could be enantioselective when using CPL, and provides a strategy for the control of the chirality of chiral coordination polymers.