Qinglian Xu

Effects of chitosan-oil coating on blue mold disease and quality attributes of jujube fruits

The effects of chitosan coating enriched with cinnamon oil on blue mold disease and quality attributes were investigated. In the in vitro experiment, the results demonstrated that the antifungal activity against P. citrinum improved with increasing concentration of chitosan or cinnamon oil. In the in vivo study, chitosan-oil treatments significantly reduced fungal decay caused by P. citrinum and all compounds with cinnamon oil at 2.0% showed complete control of the growth of P. citrinum on wound-inoculated fruits. High chitosan-oil concentrations correlated with low disease incidence regardless of storage temperature. Treatments of chitosan-oil coating also inhibited the activity of polyphenol oxidase and maintained vitamin C and phenolic compounds in wounded jujube fruits. Results suggested that the effect of chitosan coating (1.0%) enriched with cinnamon oil (0.75%) on blue mold in jujube fruits may be associated with fungitoxic properties against the pathogen and the elicitation of biochemical defense responses in fruits.

Effect of porous starch concentrations on the microbiological characteristics of microencapsulated Lactobacillus acidophilus

This study was conducted to evaluate the effect of different porous starch concentrations on the microbiological characteristics of microencapsulated Lactobacillus acidophilus. Results showed that the encapsulation efficiency of L. acidophilus with porous starch at a concentration of 10% is the highest (61.2%) compared with other concentrations. The morphology of microencapsulation was observed by scanning electron microscope. Moreover, survival assays at pH 1.5 indicated that, at the end of 3 h, the cell numbers for microencapsulation with 10% porous starch and free cells showed 2.63 and 4.01 logarithmic cycle reductions, respectively. However, no significant reduction in viable count was observed in microcapsules as well as for free cells at pH 6.5 for 3 h. The improving survival rate under high temperatures was observed with increasing concentration of porous starch from 6 to 10% and decreasing temperature. The released counts were increased with prolonged incubation time and were between 6.34 and 6.46 log CFU g(-1) at the end of storage exposure for 2.5 h to simulated colonic pH solution. These results indicated that porous starch with the optimum concentration as a carrier can be considered as an innovative technology to improve the stability of L. acidophilus.

Effect of Chitosan Coating with Cinnamon Oil on the Quality and Physiological Attributes of China Jujube Fruits

Effects of chitosan coating with cinnamon oil on the physiological attributes and preservation quality of China jujube fruits during storage at 4°C for 60 days were investigated. Results indicated that weight loss and decay of jujube fruits were significantly reduced by chitosan-oil coating during the period of 60-day storage, which also exhibited a quite beneficial effect on maintaining the sensory quality for jujube fruits. Meanwhile, the contents of vitamin C and titratable acid decreased to 3.08 mg·g−1 and 0.342% for the fruits treated by chitosan-oil coating (1.0% + 0.10%), respectively. Polyphenol oxidase, superoxide dismutase, and peroxidase activities were 13.40 U·g−1, 14.53 U·g−1, and 63.6 U·g−1 at the end of storage, respectively. The contents of total soluble phenolics and MDA were 34.51 mg·g−1 and 19.43 μmol·g−1 for the combined coating treated samples and control fruits, respectively. These results suggested that the chitosan-oil coating might be recognized as one efficiency technology on the preservation quality of jujube fruits during the storage time.

Effect of different coating materials on the biological characteristics and stability of microencapsulated Lactobacillus acidophilus

The effect of different coating materials on the biological characteristics and stability of microencapsulated Lactobacillus acidophilus was investigated. Results indicated that the surface and microstructure of microcapsules were significantly affected by the type of coating material. A complex carrier could provide protection for L. acidophilus cells against simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). Cell survivals give higher counts with 2.1 and 3.72 logarithmic cycle reduction found in microencapsulated L. acidophilus with complex wall materials and free cells after exposure to SIF for 180 min, respectively. Furthermore, at the high temperatures investigated, a higher cell survival rate in microcapsules embedded with complex materials was found than for free cells and those with other materials. Cell counts were reduced to 8.16, 7.17, and 6.42 log CFU mL−1 and 5.86, 4.29, and 2.32 log CFU mL−1 for microcapsules with complex materials and free cells treated at 50, 60 or 70 °C for 20 min, respectively. Stability was also improved compared to free cells at refrigerated temperatures. For the cells that were released from microcapsules, the counts increased with a prolonged incubation time. Moreover, the survival rate of cells with microencapsulation was better than that of free cells at high concentrations of bile salt. Results showed that for improving protection against deleterious factors, complex materials might be a better choice for the preparation of microcapsules.

Preservation Mechanism of Chitosan-Based Coating with Cinnamon Oil for Fruits Storage Based on Sensor Data

The chitosan-based coating with antimicrobial agent has been developed recently to control the decay of fruits. However, its fresh keeping and antimicrobial mechanism is still not very clear. The preservation mechanism of chitosan coating with cinnamon oil for fruits storage is investigated in this paper. Results in the atomic force microscopy sensor images show that many micropores exist in the chitosan coating film. The roughness of coating film is affected by the concentration of chitosan. The antifungal activity of cinnamon oil should be mainly due to its main consistent trans-cinnamaldehyde, which is proportional to the trans-cinnamaldehyde concentration and improves with increasing the attachment time of oil. The exosmosis ratios of Penicillium citrinum and Aspergillus flavus could be enhanced by increasing the concentration of cinnamon oil. Morphological observation indicates that, compared to the normal cell, the wizened mycelium of A. flavus is observed around the inhibition zone, and the growth of spores is also inhibited. Moreover, the analysis of gas sensors indicate that the chitosan-oil coating could decrease the level of O2 and increase the level of CO2 in the package of cherry fruits, which also control the fruit decay. These results indicate that its preservation mechanism might be partly due to the micropores structure of coating film as a barrier for gas and a carrier for oil, and partly due to the activity of cinnamon oil on the cell disruption.

Chitosan-Based Coating with Antimicrobial Agents: Preparation, Property, Mechanism, and Application Effectiveness on Fruits and Vegetables

Chitosan coating is beneficial to maintaining the storage quality and prolonging the shelf life of postharvest fruits and vegetables, which is always used as the carrier film for the antimicrobial agents. This review focuses on the preparation, property, mechanism, and application effectiveness on the fruits and vegetables of chitosan-based coating with antimicrobial agents. Chitosan, derived by deacetylation of chitin, is a modified and natural biopolymer as the coating material. In this article, the safety and biocompatible and antimicrobial properties of chitosan were introduced because these attributes are very important for its application. The methods to prepare the chitosan-based coating with antimicrobial agents, such as essential oils, acid, and nanoparticles, were developed by other researchers. Meanwhile, the application of chitosan-based coating is mainly due to its antimicrobial activity and other functional properties, which were investigated, introduced, and analyzed in this review. Furthermore, the surface and mechanical properties were also investigated by researchers and concluded in this article. Finally, the effects of chitosan-based coating on the storage quality, microbial safety, and shelf life of fruits and vegetables were introduced. Their results indicated that chitosan-based coating with different antimicrobial agents would probably have wide prospect in the preservation of fruits and vegetables in the future.

Preparation, properties and in vivo antimicrobial activity in yacon roots of microencapsulation containing cinnamon oil

Preparation, properties and in vivo antimicrobial activity in yacon roots of microencapsulated cinnamon oil were investigated. The encapsulation efficiency was affected by the concentration of wall materials. Result indicated that cinnamon oil microencapsulation exhibited different particles size and irregular shape. Thermogravimetric analysis showed that the first mass loss in curves for microparticles without oil and microencapsulated oil were observed from 43.78 to 73.59 °C and from 43.78 to 73.59 °C, respectively. The oil release of from mciroparticles could increase with improving the relative humidity and/or the temperature. The counts of bacteria and, yeast and moulds in fresh-cut yacon roots treated by microencapsulated cinnamon oil with PVC film reached the level of 4.5 × 102 and 6.3 × 103 after 12 day storage, respectively. Treatment of microencapsulated cinnamon oil could also keep the overall good visual quality for fresh-cut yacon roots.

Effects of Six Commercial Saccharomyces cerevisiae Strains on Phenolic Attributes, Antioxidant Activity, and Aroma of Kiwifruit (Actinidia deliciosa cv.) Wine

“Hayward” kiwifruit (Actinidia deliciosa cv.), widely planted all around the world, were fermented with six different commercial Saccharomyces cerevisiae strains (BM4×4, RA17, RC212, WLP77, JH-2, and CR476) to reveal their influence on the phenolic profiles, antioxidant activity, and aromatic components. Significant differences in the levels of caffeic acid, protocatechuate, and soluble solid content were found among wines with the six fermented strains. Wines fermented with RC212 strain exhibited the highest total phenolic acids as well as DPPH radical scavenging ability and also had the strongest ability to produce volatile esters. Wines made with S. cerevisiae BM 4×4 had the highest content of volatile acids, while the highest alcohol content was presented in CR476 wines. Scoring spots of wines with these strains were separated in different quadrants on the components of phenolics and aromas by principal component analyses. Kiwifruit wines made with S. cerevisiae RC212 were characterized by a rich fruity flavor, while CR476 strain and WLP77 strain produced floral flavors and green aromas, respectively. Altogether, the results indicated that the use of S. cerevisiae RC212 was the most suitable for the fermentation of kiwifruit wine with desirable characteristics.

Effect of Soft Foamed Polyethylene and/or Aluminum Material on the Properties of a Portable Mini-Cold Room

In this investigation, effects of soft foamed polyethylene (FPE) and/or aluminum (AL) material on the properties of mini-cold room were investigated. Experiments showed that the thermal conductivity of FPE material with foaming rates of 15 and 45 were 0.0270 w/m · k and 0.0334 w/m · k, respectively. Thermal conductivity improved with increasing foaming rates. The thermal conductivity and heat flux of FPE materials with different outer layers were also measured. Aluminum material could provide best heat preservation properties for the FPE insulation material. The frost accumulation and the electricity consumption of mini store-room prepared with FPE + AL material were the lowest. The decay, bleaching rate and shattering rate of table grapes were 1.9%, 7.1%, and 4.2%, and the decay rate, weight loss and fruit firmness of the apples fruits were 0.5%, 0.47%, and 8.11 Kg/cm2, respectively, after storage at 0°C for 150 days in mini cold storage prepared with FPE + AL material. The fruits of Kyoho table grapes and “Fuji” apples in this mini-cold room exhibited better quality than those in the control cold storage room. The application of mini-cold room prepared with foamed PE material covered with aluminum material could not only provide excellent thermal insulation performance, but improve the quality of fruits.