Encapsulation of lemongrass essential oil by bilayer liposomes based on pectin, gum Arabic, and carrageenan: Characterization and application in chicken meat preservation.

The volatile characteristics of lemongrass essential oil (LO) have seriously hindered its further application, and encapsulation it with multilayer modified liposomes may be an effective strategy to improve this dilemma. This study selected chitosan (CH) and three anionic polymers, pectin (P) / gum arabic (GA) / carrageenan (C), as the first and second coating polymers to modify nano liposomes (NL) by layer-by-layer electrostatic deposition, obtaining three bilayer liposomes, P-CH-NL, GA-CH-NL, and C-CH-NL as high-quality stabilized carriers of LO. The bilayer liposomes showed a dense membrane structure ranging from 110 to 150 nm uniformly, with good antioxidant properties. All bilayer liposomes had good stability during 28-day storage at 4 °C, while C-CH-NL performed relatively better inferred by smaller changes of size, PDI and Zeta potential. The total volatile base nitrogen (TVB-N) values of fresh chicken meat and a total number of bacterial colonies (TBC) experiments showed that GA-CH-NL and C-CH-NL could better retard the increase of volatile salt base nitrogen. All bilayer liposomes could delay the time for the total bacterial count to exceed 6 log CFU/g (from 7 days to 10 / 12 days). Therefore, the bilayer liposomes P-CH-NL, GA-CH-NL, and C-CH-NL may be promising natural preservatives for food products.

Aggregation studies of alpha-lactalbumin induced by edible azo dyes with different sulfonyl group numbers: A comparative study.

As an opaque and complex colloidal mixture, milk is usually present as a positively charged colloid under acidic conditions. Adding negatively charged colloids can lead to protein aggregation in milk. Alpha-lactalbumin (α-La) is an essential component of whey protein and has good physicochemical properties for functional food development. We combined spectroscopy, computer simulations, and other techniques to comparative analyze the mechanisms and characteristics of isolated α-La aggregation induced by CI Acid Red 27 (C27)/CI Acid Red 14 (FB) containing different sulfonyl groups in vitro. The results showed that C27/FB (5.25 × 10-5 mol·L-1 to 3.15 × 10-4 mol·L-1) induced the formation of fibril-like aggregates under acidic conditions (pH 2.0 and 4.0) mainly benefit from hydrophobic and electrostatic forces. Weakening and redshift of α-La's characteristics negative peak were observed (208 nm to 218 nm) on circular dichroism. ß-Crosslinks self-assembly and reorganization of disulfide bonds occurred during protein fibrillation. Moreover, the different redshift intensity of Congo red binding to amyloid fibrils was observed to be induced by C27 (>551 nm) and FB (>536 nm), and the direct observation by TEM demonstrated the ability to induce protein fibrillation is C27 > FB. Edible azo dyes with more sulfonyl groups would possess a stronger ability to induce protein fibrillation.

Uneven winter snow influence on tree growth across temperate China.

Winter snow is an important driver of tree growth in regions where growing-season precipitation is limited. However, observational evidence of this influence at larger spatial scales and across diverse bioclimatic regions is lacking. Here, we investigated the interannual effects of winter (here defined as previous October to current February) snow depth on tree growth across temperate China over the period of 1961-2015, using a regional network of tree ring records, in situ daily snow depth observations, and gridded climate data. We report uneven effects of winter snow depth on subsequent growing-season tree growth across temperate China. There shows little effect on tree growth in drier regions that we attribute mainly to limited snow accumulation during winter. By contrast, winter snow exerts important positive influence on tree growth in stands with high winter snow accumulation (e.g., in parts of cold arid regions). The magnitude of this effect depends on the proportion of winter snow to pre-growing-season (previous October to current April) precipitation. We further observed that tree growth in drier regions tends to be increasingly limited by warmer growing-season temperature and early growing-season water availability. No compensatory effect of winter snow on the intensifying drought limitation of tree growth was observed across temperate China. Our findings point toward an increase in drought vulnerability of temperate forests in a warming climate.