Use of aromatic plants and seeds extracts in the manufacture of sheep's cheese as a novel advance for the dairy industry
- Autores: Nuria Muñoz Tébar
- Directores de la Tesis: María Isabel Berruga Fernández (dir. tes.), Ana Maria Molina Casanova (codir. tes.), Manuel Carmona Delgado (codir. tes.), Laureano Gallego Martínez (tut. tes.)
- Lectura: En la Universidad de Castilla-La Mancha ( España ) en 2021
- Idioma: inglés
- Tribunal Calificador de la Tesis: Amaya Zalacain Aramburu (presid.), Manuel Viuda Martos (secret.), Carmen Cecilia Licon (voc.)
- Programa de doctorado: Programa de Doctorado en Ciencias Agrarias y Ambientales por la Universidad de Castilla-La Mancha
- Materias:
- Enlaces
- Tesis en acceso abierto en: RUIdeRA
- Resumen
One of the main causes of significant economic losses in the dairy industry is contamination and spoilage caused by molds. These microorganisms are responsible for quality reductions and could represent a health risk due to the mycotoxins production. The main method used to solve these problems is the application of plastic coatings supplemented with antibiotics or chemical preservatives. However, the overuse of plastic materials from inedible, non-renewable and non-biodegradable sources has led to major environmental issues that concern to all the stakeholders of the agri-food chain. In this sense, the growing concern of consumers about the environment and the effects of chemical preservatives on their health has led dairy industries to focus on the search for more natural and sustainable solutions.
This thesis aimed to offer more natural, biodegradable and sustainable solutions as an alternative way to control microbiological and technological defects caused by molds. To this end, the application of plant and seed products and by-products has been carried out with the aim of offering new alternative products that will assist dairy and other agri-food industries to fulfill current consumer demands, reduce the excessive use of plastics and stand out in an increasingly competitive market.
For this purpose, the in vitro antifungal activity of 5 aromatic plants (Artemisia dracunculus, Hyssopus officinalis, Lavandula stoechas, Origanum vulgare and Satureja montana) in their essential oil form and ethanolic extracts (from hydrodistillation by-products) against of wild cheese mold strains isolated and identified by molecular techniques within the species Penicillium commune/biforme, Penicillium crustosum, Aspergillus puulaauensis and Aspergillus jensenii. The results revealed that only the essential oils of oregano (Origanum vulgare) savory (Satureja montana) and tarragon (Artemisia dracunculus) were active against the tested strains and the two most potent (oregano and savory) were selected for the development of new coatings. In addition, the antioxidant activity of the extracts obtained was evaluated noting that all of them showed a remarkable antioxidant capacity.
The production of chia (Salvia hispanica) seed oil generates a large amount of by-product in the form of defatted flour. This raw material was used for the extraction of mucilage, obtaining a higher yield than whole seeds and excellent film-forming properties. Chia mucilage films were obtained by the casting method (using glycerol as plasticizer) and their characterization revealed a high biodegradability, low water vapor permeability values, a high deformation capacity and good tensile strength values, as well as good barrier properties against UV rays and visible light.
Oregano and savory essential oils were incorporated (concentrations ranging from 0.1 to 1.5 % v/v) into a coating base containing mucilage extracted from defatted chia flour previously optimized and characterized using, in addition to glycerol, food grade Tween 20 as emulsifier. The incorporation of the essential oil from both plants at 0.1-1.5 % v/v increased the solubility and WVP of the films up to 11 and 65 %, respectively. The light transmittance capacity was improved with the incorporation of savory essential oil, reducing the base film values by up to 24 %, and the addition of both essential oils at 0.1 % v/v significantly increased the deformation and tensile strength of these films. In relation to their antifungal activity, the addition of both essential oils at 1.0 and 1.5 % v/v inhibited the growth of molds reaching values ranging from 38 to 78 %. The characterized coatings, whose antifungal activity was demonstrated in vitro, were evaluated at pilot scale on pressed sheep cheese during 28 days of ripening. The application of the edible coatings did not affect pH evolution, weight loss, or normal microbial development. The coating containing oregano essential oil delayed the growth of molds on the surface of the cheeses by two weeks and by one week in the case of the coating formulated with savory essential oil, observing that the oregano coating was able to effectively inhibit the growth of molds at the end of the ripening period. On the other hand, texture was not affected by the type of coating applied, panelists detected no differences between coated and uncoated cheeses with similar overall acceptance, and cheeses coated with chia mucilage containing essential oils stood out in aroma and flavor with scores closer to the ideal value on the Just-About-Right scale. Finally, in order to meet consumer demands and offer new functional dairy products, a sheep cheese fortified with chia oil rich in α-linolenic acid was developed. The inclusion of chia oil emulsion in milk did not affect the cheese making process or the coagulation parameters, although it had a positive impact on cheese yield, dry matter, fat and α-linolenic content. Normal microbial development was not affected and the cheeses showed no signs of rancidity throughout the 32 days of ripening. Likewise, consumers found no differences between the fortified cheeses and the control cheese, and expressed good acceptance and purchase intention for this new dairy product.
