Biotecnologia Industrial

Há uma visível mudança no mercado brasileiro de cerveja, como o aumento pela demanda de cervejas diferenciadas que se distinguem pelos diferentes ingredientes, métodos de elaboração e características sensoriais. Deste modo nota-se a necessidade de obtenção de
cervejas com novos e variados aromas que atendam diferentes grupos de pessoas. Para comprovar a aceitação de uma cerveja elaborada com café, decidiu-se fazer uma pesquisa mercadológica antes da fabricação da cerveja para mensurar a aceitação do novo produto. Para essa pesquisa foram submetidos a um questionário on-line, 211 consumidores de ambos os sexos, maiores de 18 anos e consumidores de bebidas alcoólicas. O perfil dos consumidores que responderam ao questionário, era de maioria homens. A maioria dos entrevistados elege como bebida alcoólica preferida a cerveja, ingere de 2 a 3 vezes por
semana e prefere bebe-la em sua própria casa. Os itens mais importantes dessa bebida devem ser o sabor e o preço. Os estilos preferidos são as cervejas Pilsen e IPA. Os atributos mais importantes de uma cerveja devem ser o sabor e o aroma. Sessenta por
cento dos entrevistados ainda não tomaram uma cerveja de café, e os que já tomaram, mais de sessenta por cento gostaram. Analisando os hábitos dos consumidores de cervejas, observou-se um aumento pela procura por cervejas diferenciadas e com mais sabor e uma possível grande aceitação no mercado de cervejas aromatizadas com café.

Polyelectrolyte complexes (PECs) of biopolymers have been used for many applications, including emulsion stabilization and improvements in the properties of biopolymers, such as interfacial tension. The enhance of interfacial activity of biocompatible compounds is essential to the development of new natural stabilizers. Thus, the aim of this study was to understand how modifications on chitosan structure affect the interfacial tension of PECs. Positive, neutral and negative PECs were formed by varying chitosan or chitosan oligomers: whey protein isolate (WPI) mass ratios. Hydrolysis reduced chitosan size and increased zeta potential. FT-IR, H NMR analyses and crystallinity index confirmed structure modification. Chitosan oligomers showed lower crystallinity index and higher deacetylation degree than native chitosan. Positive
chitosan PEC showed the lowest interfacial tension, suggesting a strong adsorption at interface oil-water and better interfacial stabilization than other PECs. Therefore, changes on chitosan structures enhance PECs interfacial properties and its use as emulsion stabilizer.

Consumers have sought to adopt a healthier lifestyle by avoiding the use of foods with artificial preservatives. To meet this demand, a solution would be the use of natural preservatives. There are foods that already have natural antimicrobials such as milk (which has lactoferrin), eggs (lysozyme) and crustaceans (chitosan). There are also bacteriocins produced by bacteria to inhibit others, nisin. All these antimicrobials are non-toxic and can be applied to foods as natural preservatives. In this review, we detail each natural antimicrobial and the possible food application that can be directly or through films, coatings, packaging and encapsulation.

Lactoferrin (L) and gellan gum (G) nanoparticles were produced in different biopolymer proportions through electrostatic complexation to enhance the antimicrobial properties of lactoferrin. The nanoparticles were characterized according to size, charge density, morphology and antimicrobial activity against S. aureus and E. coli, in two different broths to show the effect of the broth composition on the nanoparticle activity. The 9L:1G particles showed the highest positive zeta potential (+21.20 mV) and reduced diameter (92.03 nm) which resulted in a minimum inhibitory concentration six times smaller (0.3 mg/ml) than pure lactoferrin (2 mg/ml). However, the bacteriostatic action of nanoparticles was inhibited in the presence of divalent cations. When applied to strawberries as a coating, lactoferrin nanoparticles extended fruit shelf-life up to 6 days in the presence of carboxymethylcellulose (CMC). Therefore, lactoferrin-gellan gum complexation was proved to be a promising tool to enhance lactoferrin antimicrobial action and broaden its application as a food preserver.

The aim of the present study was to produce lactoferrin (L) and chitosan (C) nanoparticles by ionic cross-linking with TPP and thereby increase the antimicrobial activity of biopolymers. The nanoparticles were synthesized in different proportions of biopolymers and TPP and characterized regarding their size, zeta potential, morphology, chemical interactions, structural characteristics, and antibacterial activity. They were also applied as coatings on strawberries with the aim of increasing fruit shelf-life. Circular dichroism spectra revealed that the addition of TPP altered the secondary structure of lactoferrin. The nanoparticles 3.5L:5.5C:1TPP and 4.5L:4.5C:1TPP showed higher zeta potential values and lower hydrodynamic diameters (+39.30 mV, 81.87 nm and +33.07 mV, 97.67 nm, respectively) and intense bacteriostatic action against S. aureus (0.0370 mg/ml and 0.0463 mg/ml, respectively). The minimum inhibitory concentration of these nanoparticles was three times lower than those of pure biopolymers. When applied to strawberries coating, the nanoparticles delayed the ripening and degradation of the fruit. These results confirm that it is possible to intensify the antimicrobial properties of lactoferrin and chitosan through ionic cross-linking with TPP and, thus, expand their use as natural food preservatives.

Application of hydrophobic coatings, such as carnauba wax nanoemulsions, combined
with natural antimicrobials, has been demonstrated to be an effective solution in extending the shelf life of fruits. The present study evaluated the effectiveness of carnauba wax nanoemulsion (CWN) coatings containing free or encapsulated with β-cyclodextrin (β-CD) essential oils of Syzigium aromaticum (CEO) and Mentha spicata (MEO) for the post-harvest conservation of papaya fruit. The chemical composition of the essential oils (EOs) was analyzed using GC-MS. Subsequently, coatings
incorporating free and encapsulated EOs were prepared and applied to papaya fruit. Fruit was evaluated for post-harvest quality parameters during 15 days of storage. Clove essential oil presented as main compounds eugenol (89.73%), spearmint and carvone (68.88%), and limonene (20.34%). The observed reduction in weight loss in coated fruit can be attributed to the formation of a physical barrier provided by the coating. Compared to the control group, which experienced the highest
weight loss of 24.85%, fruit coated with CWN and CWN-MEO:β-CD exhibited significantly lower weight loss percentages of only 5.78% and 7.5%, respectively. Compared to the control group, which exhibited a release of ethylene at a rate of 1.3 µg kg−1 h −1 , fruit coated with CWN, CWN-MEO:β-CD, and CWN-MEO coatings demonstrated a lower ethylene release rate at 0.7 µg kg−1 h −1 . Although the physical-chemical properties of papayas, including pH, Brix, titratable acidity, color, and texture, remained largely unchanged during storage with the coatings, analysis of incidence and severity of papaya post-harvest deterioration revealed that coatings containing essential oils effectively acted as antifungals in the fruit. Microscopy images showed that CWN and CWN-MEO:β-CD coatings are  more uniform compared to the others. The edible coatings, especially CWN and CWN-MEO: β-CD, can act as antimicrobial coatings on papaya fruit, increasing their conservation during post-harvest storage.

Chitosan (CS) nanoparticles were formed by two different methodologies: ionic (with sodium tripolyphosphate-TPP) and chemical (with genipin-GN) cross-linking. CS-TPP and CS-GN nanoparticles showed positive zeta potential (+46.24 and +62.86 mV, respectively) and sizes ranging from 83.70 to 835.91 nm, respectively. Ionic cross-linking (with TPP) resulted in particles smaller than those formed by chemical cross-linking (with GN). The in vitro antibacterial activity revealed an efficient inhibitory effect, especially regarding CS-TPP. In situ, antibacterial and antioxidant studies were carried out on O/W emulsions. The mesophilic and psychrotrophic counts, peroxide value and quantification of conjugated dienes and trienes during time revealed that nanoparticles tend to improve the microbiological and oxidative stability of emulsions. These findings underline the direct relationship between the reduction of particle size and the increase in biopolymer functional properties and expand the possibilities of CS application as a natural preservative of emulsified systems.

As cervejas distinguem-se pelos diferentes ingredientes, métodos de
elaboração e características sensoriais. As cervejas artesanais ou especiais, em geral, são cervejas que utilizam receitas ou processos de fabricação diferentes das produzidas em larga escala. Também chamadas de cervejas premium ou gourmet, as cervejas especiais
enquadram-se em uma categoria de qualidade superior e de alto valor agregado. Nesta pesquisa, produziu-se uma cerveja gourmet aromatizada com café, com o objetivo de contribuir para o desenvolvimento da produção de cervejas especiais. A análise sensorial demonstrou que a cerveja produzida com 45% de café foi a melhor aceita,
dentre as cervejas formuladas, em todos os quesitos e intenção de compra. Conclui-se, que o café poderá ser empregado como aromatizante no processo de produção de cerveja com até 45% de café, sem interferir no processo fermentativo.