Effects of interactions between the constituents of chitosan-edible films on their physical properties

The main objective of this work was to evaluate the effect of chitosan and plasticizer concentrations and oil presence on the physical and mechanical properties of edible films. The effect of the film constituents and their in-between interactions were studied through the evaluation of permeability, opacity and mechanical properties. The effects of the studied variables (concentrations of chitosan, plasticizer and oil) were analysed according to a 2 3 factorial design. Pareto charts were used to identify the most significant factors in the studied properties (water vapour, oxygen and carbon dioxide permeability; opacity; tensile strength; elongation at break and Young's modulus). When addressing the influence of the interactions between the films' constituents on the properties above, results show that chitosan and plasticizer concentrations are the most significant factors affecting most of the studied properties, while oil incorporation has shown to be of a great importance in the particular case of transport properties (gas permeability), essentially due to its hydrophobicity. Water vapour permeability values (ranging from 1. 62 × 10 -11 to 4. 24 × 10 -11 g m -1 s -1 Pa -1) were half of those reported for cellophane films. Also the mechanical properties (tensile strength values from 0. 43 to 13. 72 MPa and elongation-at-break values from 58. 62% to 166. 70%) were in the range of those reported for LDPE and HDPE. Based on these results, we recommend the use of 1. 5% (w/w) chitosan concentration to produce films, where the oil and plasticizer proportions will have to be adjusted in a case-by-case basis according to the use intended for the material. This work provides a useful guide to the formulation of chitosan-based film-forming solutions for food packaging applications.The author MA Cerqueira is a recipient of a fellowship from Fundacao para a Ciencia e Tecnologia (FCT, SFRH/BD/23897/2005) and BWS Souza is a recipient of a fellowship from the Coordenacao Aperfeicoamento de Pessoal de Nivel Superior, Brazil (Capes, Brazil)

Effect of different coating-forming agents on the efficacy of the biocontrol agent Candida sake CPA-1 for control of Botrytis cinerea on grapes

[EN] Multiple formulations of known biocontrol agent (BCA) Candida sake, containing different coatingforming polymers and surfactants were tested at different polymer:BCA ratios, in order to improve control of Botrytis cinerea on grapes. The BCA cell viability on the grape surface was analyzed and reduction in disease incidence and severity was determined. Coating-forming solids improved the survival and effi- cacy of C. sake as a BCA against B. cinerea, depending on the polymer type and ratio. The incorporation of surfactants did not improve survival or disease control, although they promoted a better cell dispersion on the grape surface. Cell growth of the antagonist during incubation led to the formation of aggregates, even when surfactants were present. Sodium caseinate and starch were the most suitable polymers to formulate C. sake preparations to obtain coating-forming systems with this BCA and to increase its survival and efficacy at the minimum economic cost of the ingredients. 2016 Elsevier Inc. All rights reservedThe authors are grateful to the Spanish Government for the financial support from the national project RTA2012-00067-C02 (Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria, Spain and FEDER founds) and to the Conselleria d'Educacio of the Generalitat Valenciana, (Spain) for A. Marin's PhD grant.Marín-Gozalbo, A.; Cháfer Nácher, MT.; Atarés Huerta, LM.; Chiralt, A.; Torres, R.; Usall, J.; Teixidó, N. (2016). Effect of different coating-forming agents on the efficacy of the biocontrol agent Candida sake CPA-1 for control of Botrytis cinerea on grapes. Biological Control. 96:108-119. https://doi.org/10.1016/j.biocontrol.2016.02.012S1081199

Quitosana no controle pós-colheita da podridão mole em caqui 'rama forte' Chitosan on the postharvest control of soft rot in 'rama forte' persimmon

Este trabalho objetivou avaliar o efeito da quitosana, aliada ao processo de destanização, no controle de Rhizopus stolonifer em caqui 'Rama Forte' e sobre o crescimento micelial do fungo in vitro. Caquis foram submetidos ao processo de destanização com CO2 (70% / 18 horas), em tambores herméticos, sendo em seguida submetidos à inoculação com suspensão de esporos de R. stolonifer (3x10(5) esporos mL-1). Após inoculação, os frutos permaneceram por 2 horas a 25 °C, quando foram imersos em quitosana (0; 0,5; 1,0; 1,5 e 2,0%), por 1 minuto. Os frutos foram mantidos a 25 °C / 80% UR e avaliados quanto à severidade e incidência da podridão mole, durante cinco dias. Após o período de armazenamento, avaliaram-se a coloração de casca, a firmeza e o índice de adstringência. In vitro, avaliou-se o crescimento micelial em placas contendo meio BDA incorporado com quitosana ou ácido cítrico. Os resultados mostraram que a quitosana, a 1,5%, reduz a severidade e a incidência da podridão mole em caquis e não influencia no processo de perda de adstringência, firmeza e na coloração de casca. In vitro, a quitosana inibe completamente o crescimento micelial de R. stolonifer, em concentração tão baixa quanto 0,5%.<br>The objective of this research was to evaluate the effect of chitosan in addition to de-astringency process on the control of Rhizopus stolonifer in 'Rama Forte' persimmon and on in vitro mycelial growth. Persimmon were submitted to de-astringency process using CO2 (70% / 18 h), in hermetic chambers. Next, fruit were inoculated through subcuticular injections of a R. stolonifer spore suspension (3x10(5) spore mL-1) and 2 hours later at 25 °C immersed into chitosan (0, 0.5, 1.0, 1.5, and 2.0%), for 1 min. Fruit were stored at 25 °C / 80% RH, and checked for rot severity and incidence of soft rot, during 5-days of storage. After storage the skin color, firmness and astringency index were evaluated in persimmons. In vitro, mycelial growth was evaluated on PDA media emended with chitosan or citric acid. Chitosan 1.5% reduces severity and soft rot incidence and does not influence the astringency loss, firmness and skin color. In vitro, chitosan at concentration completely inhibited the R. stolonifer mycelial growth at concentration < 0.5%