تهیه و ارزیابی خصوصیات نانوالیاف فعال الکتروریسی شده برپایه پلی کاپرولاکتون حاوی کمپلکس اسانس دارچین/بتاسیکلودکسترین

افزودن ترکیبات زیست فعال به داخل ماتریس نانوالیاف الکتروریسی شده و تولید بسترهای فعال یکی از جدیدترین رویکردهای نگهداری مواد غذایی محسوب می‌شوند. هدف: هدف از این پژوهش تولید نانوالیاف الکتروریسی شده فعال آنتی اکسیدانی برپایه‌ی پلی کاپرولاکتون (pcl) حاوی اسانس دارچین به شکل آزاد و درون پوشانی شده در بتاسیکلودکسترین بود. روش کار: اسانس دارچین به روش کلونجر استخراج شد و تشکیل کمپلکس اسانس/بتاسیکلودکسترین به روش اولتراسونیکاسیون انجام شد. سپس از pcl به روش الکتروریسی نانوالیاف تهیه شد و اسانس آزاد و کمپلکس شده، در غلظت‌های 0.5 و 1 درصد به ترکیب الیاف افزوده شد. خصوصیات مورفولوژیکی، ساختاری، حرارتی، آبگریزی سطحی و مکانیکی نانوالیاف و همچنین ظرفیت احیاکنندگی رادیکال‌های آزاد dpph تعیین شد. نتایج: آزمون ftir تشکیل پیوندهای هیدروژنی جدید بین اسانس، بتاسیکلودکسترین و pcl را اثبات کرد. نتایج آزمون fesem نشان داد که افزودن اسانس آزاد، شکل رشته‌ای نانوالیاف را تخریب می‌کند اما پس از تشکیل کمپلکس با بتاسیکلودکسترین، مورفولوژی الیاف تغییری نکرد. ماهیت بلورین و شکل شبکه‌ی کریستالی پس از افزودن کمپلکس اسانس دارچین/بتاسیکلودکسترین تغییر کرد. با افزودن اسانس آزاد تغییری در خواص حرارتی ایجاد نشد اما با افزودن کمپلکس، دمای ذوب نانوالیاف pcl بیشتر شد. اسانس آزاد، خصوصیات مکانیکی فیلم را تضعیف کرد اما کمپلکس اسانس/بتاسیکلودکسترین در غلظت 0.5 درصد به افزایش استحکام کششی منجر شد و در غلظت 1 درصد دوباره باعث کاهش این ویژگی گردید. افزودن اسانس آزاد و درون پوشانی شده، آبگریزی سطحی نانوالیاف را افزایش داد و کمپلکس اسانس/بتاسیکلودکسترین در غلظت 0.5 درصد بیشترین تاثیر را داشت. نانوالیاف حاوی 1 درصد اسانس بیشترین قدرت مهارکنندگی رادیکال آزاد dpph را نشان دادند اما تشکیل کمپلکس با بتاسیکلودکسترین تاثیر معنی داری بر روی خاصیت آنتی اکسیدانی نانوالیاف نداشت. نتیجه گیری نهایی: نتایج این پژوهش نشان داد بارگذاری اسانس دارچین بر روی نانوالیاف pcl به منظور تولید بستر فعال آنتی اکسیدانی امکان پذیر است و تشکیل کمپلکس با بتاسیکلودکسترین، خصوصیات فیزیکی نانوالیاف را بهبود می‌بخشد.

Preparation and evaluation of the characteristics of active electrospun nanofibers based on polycaprolactone containing cinnamon essential oil/βcyclodextrin inclusion complex

Introduction: Oxidation is one of the main factors affecting the shelflife of food susceptible to lipid deterioration (Almasi et al., 2014). To reduce oxidation in sensitive food products, the direct addition of antioxidants to food formulation, dipping food in antioxidant solution and the design of a suitable vacuum or modified atmosphere packaging technology are the three most common alternatives. However, there are many foodstuffs that cannot be protected in these ways, as they are fresh or raw foodstuffs in which the addition of other substances is not permitted. One of the most promising systems to protect the foods against oxidation is to use an antioxidant active packaging. Active nanofibrous mats synthesized by electrospinning technique is a novel type of food active packaging materials. The electrospinning process is an electrohydrodynamic phenomenon forming micro and nanoscale fibers by applying electrical force on a polymeric solution (Forghani et al., 2021). Poly(caprolactone) (PCL) is an aliphatic polyester filmforming candidate widely used in pharmaceutical and biomedical applications owing to its biodegradability, biocompatibility, and high mechanical properties, but recent studies have increasingly focused on the potential of PCL for electrospun nanofibers preparation with food packaging application purposes. Cinnamon has been widely used in the food industry. The dried inner bark of the tree and the milled bark are the commercial forms of cinnamon. Cinnamon essential oil (CEO) obtained from bark of the plant has been found to have an effective antimicrobial activity and listed as GRAS by the Food and Drug Administration (Zhang et al., 2017). Cinnamaldehyde, the major active component of CEO, has been shown to have broadspectrum antimicrobial activity and a good antioxidant activity (Ojagh et al., 2010). In the development of an active packaging, it is a challenge to design of a controlled release system. Many approaches have been utilized for release controlling of active agents from packaging materials. Complexation with cyclodextrins (CDs) in aqueous solutions is an effective method for release controlling especially for herbal extracts and EOs. Amongst the CDs, Betacyclodextrin (βCD) is widely used for release controlling of bioactive compounds from active packaging (Sun et al., 2014). The aim of this work was to fabricate the antioxidant active nanofibers based on PCL containing CEO in the free form and βCDcomplex form. The physical and morphological properties of nanofibers were investigated and also their antioxidant activity was studied.Materials and methods: The CEO was extracted by hydrodistillation method and the CEOβCD inclusion complex was fabricated by ultrasonication method. The PCL in the concentration of 10% w/v was dissolved in ethanol/dichloromethane mixture solvent and after that, the free CEO and CEOβCD inclusion complex were added in the concentrations of 0.5% and 1% w/w of PCL. The prepared solutions were loaded into a 5 mL plastic syringe equipped with a blunttipped 21gauge stainless steel needle. Then, the electrospinning was carried out by applying a high voltage power of 15 kV and a flow rate of 1.0 mL/h at 25 ± 2 °C and 30 ± 1 % relative humidity. Nanofibers were collected on an aluminum foil collector with a horizontal distance of 10 cm from the needle tip (Amjadi et al., 2020). The structural parameters of films were analyzed by FTIR, XRD and FESEM tests. Water contact angle and mechanical properties were also studied. Antioxidant activity of films was examined by DPPH scavenging method. The oneway ANOVA method by using SPSS software was used for statistical analysis of obtained data.Results and discussion: FTIR analysis confirmed the formation of new hydrogen bonds between CEO and PCL in the free form and encapsulated in βCD. XRD test revealed that free CEO had no effect on semicrystalline structure of PCL nanofibers. But the CEO βCD inclusion complex caused to increase the intensity of peaks related to crystallinity of PCL increased. According to FESEM images, the free CEO addition disrupted the uniformity and ordered design of PCL nanofibers but the CEOβCD inclusion complex addition produced uniform nanofibers without beads. The water contact angle and Young’s modulus of mats increased but strain to break decreased by addition of CEOβCD inclusion complex. The nanofibers containing 1 % free CEO and CEOβCD inclusion complex had the highest DPPH scavenging activity. Conclusions: The results of this research demonstrated the successfulness of active PCL nanofibers preparation by electrospinning process. The CEOβCD inclusion complex was incorporated into PCL nanofibers. The addition of CEO in the free form had adverse effect on the physical, thermal and structural properties of nanofibers. But when CEOβCD inclusion complex was used, the improved properties of nanofibers were observed. The PCL active nanofibers had strong antioxidant potential and was proposed as potential antioxidant active packaging. This research approved the good antioxidant effect of CEO loaded PCL nanofibers. Therefore, it would be suitable for those foods such as edible oils, butter and other fatty foods, suffering from oxidative deterioration as their main problems. Further studies are required to investigate the effects of fabricated active nanofibrous mats on the shelflife extension of real food systems.