Effects of nano-chitosan coatings incorporating with free /nano-encapsulated cumin (Cuminum cyminum L.) essential oil on quality characteristics of sardine fillet
Introduction
Increasing demand for natural biological compounds, coupled with customer concern about the use of chemical preservatives, has led to a new trend in the food industry called (green consumerism) to try alternative approaches to food preservation (Shariatifar et al. 2020). Among natural additives, essential oils (EOs) and extracts have a high potential for use in the field of green consumerism due to their biological properties (Ghaderi-Ghahfarokhi et al. 2017).
Fish fillet is prone to microbial spoilage and fat oxidation because of its low oxidative stability and special composition. Delay in microbial growth at the fish surface using active coatings seems to be a good way to maintain fish quality for a longer time and increase its shelf-life (Pabast et al. 2018). Fish contain high levels of moisture (65–80%), free amino acids (AA) and another non-protein nitrogenous compounds (9–18%) and fat (7–11) that these factors cause many microbial, physical and biochemical changes when stored at refrigerator temperature (4 °C) (Wu et al. 2015). The sardines often reside in coastal areas and live in groups. Sardines are one of the most important marine resources that are harvested in many parts of the world and in Iran (Darvishi et al. 2013; Dib et al. 2018).
Cumin (Cuminum cyminum L.) is an herb of the Apiaceae family that is of great economic value due to its special aroma, medicinal, therapeutic and edible properties. The most important producing countries are Iran, Egypt and Morocco (Rana 2014). Some of its important pharmacological properties are antioxidant, antibacterial and antifungal properties. EOs are aromatic oils which arise from different parts of plants. The antioxidant and antimicrobial properties of EOs have been recognized for many years, but it has not been long before scientific circles have increased their interest in investigating the various aspects of these effects (Taherkhani et al. 2015; Ziaee et al. 2014). However, some compounds of extracts and EOs, including chemically active compounds such as phenolic compounds, are rarely present in food matrices.These problems include the negative impact of these compounds on the physical stableness and chemical food integrity and the loss of bioactive activity of bioactive compounds (Pabast et al. 2018; Sharafati Chaleshtori et al., 2016).
Encapsulation could offer a probable way to conquer these problems through the following methods: Improve the oxidative stability of compounds, limit the reaction of these compounds with food, protect their constancy during process of food and maintenance, and provide controlled and targeted release conditions (Donsì et al. 2011; Gibis et al. 2012). Nano-liposomes are high surface area phospholipids that made with amphiphilic molecules consisting of a fat-soluble hydrophobic tail and a water-soluble hydrophilic head. Although the impact of nano-encapsulated bioactive compounds on food and beverage storage has been investigated, few researches have been led on the use of these compounds for the storage of solid foods such as fish, meat and fruit that it is not possible to apply these nanocapsules directly (Alexander et al. 2012; Pabast et al. 2018). The integration of nano-liposomes with edible coatings could provide a novel way of removing this limitation and fixing the nano-liposomes on the food surface. This method, in addition to fixing nano-liposomes on the surface of food, causes the following: Adjusting the release of active ingredients, reducing the impact of plant extract taste, reducing the rate of penetration, reducing the concentration of extract needed to achieve the expected effects, enhancing active packaging activity and ultimately improving the performance of edible coatings (Ghaderi-Ghahfarokhi et al. 2017).
Also, edible coatings reduce the spoilage and contamination of food through its specific function as a barrier against moisture and gas, as well as the migration of soluble materials during processing, distribution and storage. Numerous studies have shown reliable results of the application of antimicrobial nanoliposomes with coatings of bio-based to growth the shelf-life of fish products (Donsì et al. 2011; da Silva Malheiros et al. 2012; Dib et al. 2018).
Chitosan is a natural polysaccharide extensively used in the food trade that is industrially produced from the diacetylation of crustacean chitin such as insects, crabs, shrimp, lobsters and the cell wall of certain types of algae and fungi (Aşik and Candoğan 2014; Haghju et al. 2016; Simpson et al. 1997). Many researches have told which chitosan coatings are effective for carrying lipophilic bioactive compounds and can have a synergistic effect with extracts incorporated with it due to its antimicrobial nature. In addition, other researches have reported the constancy of liposomes and its homogenous dispersal in the film of chitosan due to the much viscosity of the solution of chitosan and the complex created by the liposomes negative charge (−) and the charge of positive (+) of the amine groups of chitosan (Kanatt et al. 2013; Ojagh et al. 2010).
However, edible coatings involving polysaccharides such as chitosan alone are not a good barrier against gas and water vapor due to their hydrophilic groups. A novel method to advance the structure of edible coatings is the use of nanoliposomes, which to date have not investigated the characteristics of edible film and edging coatings including nanoliposomes and their application to fish coatings (Pabast et al. 2018; Sharafati Chaleshtori et al., 2016). Nowadays, in addition to the usual methods of increasing the shelf life of foods, the use of new technologies and complementary food preservation techniques such as antimicrobial and antioxidant packaging using biodegradable films and edible coatings, have received much attention (Mohammed et al. 2004; Noori et al. 2018). Chitosan can be used as a coating for other natural polymers if desired.
The most interesting and unique properties of this material are its antimicrobial ability and ability to absorb heavy metal ions, the first being related to increasing shelf life and food safety and the second being related to reducing food oxidation (Ghaderi-Ghahfarokhi et al. 2017; Helander et al. 2001).
The techniques of nanochitosan preparation include: Microemulsion Technique, Method of Ionotropic Gelation, Technique of Polyelectrolyte Complex (PEC), Method of Emulsification-Cross Linking, Technique of Complex Coacervation, Technique of Solvent Evaporation and Co-precipitation Method (Haghju et al. 2016; Kanatt et al. 2013).
The use of encapsulated active agents as controlled-release and delivery systems in bioactive coating and packaging is rare but is increasing in recent researches. To the best of our understanding, there aren't results on the construction of active edible coatings by CCEO and nanoliposomes of EO loaded. Furthermore, no certain data existing on the using of the edible coating such as nanoliposomes of CCEO loaded in sardine fish produces (Jung et al. 2009; Ziaee et al. 2014).
This study is performed to the development of systems of bioactive packaging through the combination of nanoliposomes of CCEO loaded into coating of nanochitosan based and assessment of its biological activity on sardine fillet shelf life.
Section snippets
Materials
Methanol, sodium carbonate anhydrous, dichloromethane, Cholesterol (95%), Folin-Ciocalteu reagent, acetic acid, glycerol (>97% purity) and powder of chitosan (molecular weight: 190–310 kDa) with a deacetylation grade of 75–85% were obtained from Merck Company (Darmstadt, Germany). Other solvents and reagents were got by Merck Company (Darmstadt, Germany) and were grade of analytical (upper available purity). Granular phospholipid (L-a-lecithin) (with pure of 99%) for preparation of
Identification of compounds of cumin essential oils (CCEO)
In this research, 25 components amounting to 99.1% of the CCEO were recognized (Table 1). The main components were γ- Terpinene, Benzenemethanol α.-propyl, 2- β-pinene, p-cymene and cumin aldehyde. Rana in 2014 was exposed the EO from the CC seeds and isolated using technique of hydrodistillation and the chemical composition was measured by GC/MS. In this research, a sum of 26 components, indicating 96.7% of the oil were recognized. Cuminaldehyde, β-pinene, γ- terpinene, p-cymene, p-cymen-7-ol,
Conclusion
The results of chemical and microbial analyses showed that chitosan coating including nano-encapsulated CCEO on sardine could conduct to expansion of shelf-life, enhancement of microbiological safety and holding of the good quality specification in storage period at 4 °C. All samples of coated reduced significantly counts of microbial than uncoated samples. In general, CCEO encapsulation allows the control of microbial agents on the surface of samples, leading to prolonged antimicrobial
Declaration of competing interest
We have no conflicts of interest to declare.
Acknowledgements
This study has been supported by the Tehran University of Medical Sciences and Health Services (TUMS).
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