Starch is a promising source of biopolymers and the incorporation of essential oils (EOs) into it can improve some biological properties of films. This study aimed at developing and characterizing barrier, biodegradability and optical properties of biopolymeric films made from arrowroot starch and at incorporating EOs from Piper aduncum leaves and inflorescences in order to analyze their antifungal activity against Rhizopus microsporus and Colletotrichum gloeosporioides. The casting method was used for developing arrowroot starch films and incorporating EOs into them. Resulting films exhibited satisfactory barrier properties, low water vapor permeability (WVP), transparency and good barrier property against UV-vis light, besides being 100% biodegradable. In addition, films enriched with EOs at 0.75% and 1.0% revealed promising antifungal activity. Results showed, for the first time, that arrowroot starch enriched with EOs from P. aduncum can potentially be used as an active film due to its excellent physicochemical properties and antimicrobial activity.

RESUMO: Existem fatores que podem afetar o conteúdo de óleo essencial das plantas, sendo o horário de coleta um deles. Assim, observa-se que o teor e a composição química de óleo essencial podem variar em certas plantas de acordo com horário de coleta. O objetivo deste trabalho foi avaliar o efeito do horário de coleta sobre o conteúdo e a composição química do óleo essencial das folhas de goiabeira ( Psidium guajava ). Folhas de Psidium guajava foram coletadas em diferentes horários do dia para determinar teor e composição química de seu óleo essencial. O óleo essencial não apresentou variação qualitativa da composição química em relação ao horário de coleta das folhas de Psidium guajava , mas alterou a concentração das substâncias, entre elas o α-humuleno e o trans-cariofileno. Os constituintes principais do óleo essencial das folhas de Psidium guajava são o limoneno (2,2-4,4%), trans-cariofileno (18,1-17,1%), α-humuleno (26,3-20,4%), aromadendreno (7,6-12,2%), α-selineno (7,3-11,3%), óxido de cariofileno (3,7-3,3%) epóxido de humuleno II (4,1-1,9%) e o selin-11-en-4α-ol (7,2-11,1%). No entanto, a maior produção de óleo essencial, foi obtida com as folhas coletadas às 19h, apresentando conteúdo de 0,38% (b.s.) e a mais baixa produção às 07h, apresentando conteúdo de 0,24% (b.s.). Através da análise química, identificou-se que compostos sesquiterpênicos apresentaram uma maior concentração (62,0%) e os monoterpenos e monoterpenoides foram os que apresentaram menor concentração (2,2 e 1,1%, respectivamente). As classes que sofreram maiores mudanças em relação ao horário de coleta foram os monoterpenos (2,2-4,4%) e os sesquiterpenos e os sesquiterpenoides (63,8-61,7% e 15,9-13,2%, respectivamente).

ABSTRACT: The essential oil plants contents can be affected by several factors. For example, in certain plants, collection time has been observed to affect the content and chemical composition of the essential oil obtained from the plant. The objective of this study was to evaluate the effect of collection time on the content and chemical composition of the essential oil from guava ( Psidium guajava L.) leaves. Leaves were collected at different times of the day and the content and chemical composition of their essential oil was determined. Collection time did not qualitatively affect the chemical composition of the essential oil. However, concentration of certain substances in the oil, such as α-humulene and trans-caryophyllene, did significantly vary at different collection times. The main constituents of the essential oil of Psidium guajava are limonene (2.2-4.4%), trans-caryophyllene (18.1-17.1%), α-humulene (26.3-20.4%), aromadendrene (7.6-12.2%), α-selinene (7.3-11.3%), caryophyllene oxide (3.7-3.3%), humulene epoxide II (4.1-1.9%), and selin-11-en-4α-ol (7.2-11.1%). Leaves collected at 7:00 AM had higher essential oil production, with a content of 0.38% (d.b.), whereas leaves collected at 7:00 PM had lower essential oil production, 0.24% (d.b.). Chemical analysis showed that sesquiterpene compounds represented the highest concentration (62.0%), and monoterpenoids and monoterpenes represented the lowest concentrations (1.1 and 2.2%, respectively). Chemical classes that underwent major changes with respect to collection time were monoterpenes, sesquiterpenes, and sesquiterpenoids (2.2-4.4%, 63.8-61.7%, and 15.9-13.2%, respectively).