Fig tree bioresidues as natural preservatives in fig-based products

Mestrado de dupla diplomação com a Université Libre de TunisThe food processing and storage became imperative to provide the quotidian needs of humans. Therefore, the use of artificial additives started to be mandatory to decrease or postpone the nutritional value losses due to chemical, microbiological and enzymatic changes, thus maintaining the characteristics of the processed food for a longer period. Nevertheless, the use of synthetic additives has been highly studied due to several scientific alerts about their harmful effects that can include allergic problems, asthma, among others. This situation leads to a deep search for natural alternatives able to serve the same purpose. To do so, food industries started this mission through the extraction of natural compounds from microorganisms, animals, plants and agri-food bio-waste. Indeed, among the food industry, several sectors produce huge amounts of bio residues. Figs, for instance, are known for their richness in minerals and nutrients, which leads to their high consumption, thus generating several fig bio-wastes, which include fig leaves that could be useful for the recovery of bioactive compounds, such phenolic compounds, to act as natural preservatives, hence, valorizing fig-waste and promoting circular economy. Therefore, in the present work, fig leaves from five different varieties, namely Dauphine (Da), Longue d’Aout (La), Bourjassote Noire (Bn), Marseille (Ma) and Pasteliere (Pa) were screened to determine their phenolic content by HPLC-DAD-ESI-MS as well as their bioactivities, namely antioxidant through the TBARS and CAA assays, antimicrobial by the microdilution method, anti-inflammatory using RAW 264.7 mouse macrophage cell line and cytotoxic through the sulforhodamine B assay. The extraction of total phenols was optimized through response surface methodology and carried out by dynamic maceration and ultrasound assisted extraction, being their determination assessed by the Folin ciocalteu assay. Finally, the extracts obtained from the optimal conditions of ultrasound assisted extraction, used as a cost effective method, were mixed together searching for possible synergistic effects. When the leaves acted together, the antioxidant activity was higher, since the lowest EC50 recorded for Bn was 0.23±0.01 mg/mL, and for the mixture an EC50 of 0.12 ±0.01 mg/mL was achieved. Moreover, the mixture also revealed promising results regarding the antimicrobial activity by acting against all the tested bacteria and fungi strains. It was important to showcase that the mixture revealed activity against Pseudomonas aeruginosa with a MIC of 10 mg/mL. In addition, as the extracts showed no toxicity against normal cell line PLP2 with a GI50>400 μg/mL, a concentration of 10mg/mL was incorporated, after the cooking process, at 80°C and 50°C in two formulations of fig jams (extracts with honey and extracts without honey) to determine the efficiency of the developed extracts, acting as natural preservatives, and their stability in the final products. The fig jams were subjected to the evaluation of physical parameters (color, texture, aw and pH), nutritional (moisture, ash, fat using soxhlet, protein by the kjeldahl method, carbohydrates and energy) and chemical profiles as the free sugars by HPLC-RI and fatty acids through the GC-FID, and microbial load following ISO procedures. The low-sugar fig jam incorporated with natural fig leaf preservatives revealed that the incorporation did not change the overall appearance of the jams. Regarding the nutritional and chemical properties, the formulas presented low sugar, low protein content and high amount of carbohydrates, low fatty acids content with palmitic acid as the major compound. Furthermore, the different temperatures of incorporation showed no discernible changes over time, implying that the molecules of interest present in the extracts are not thermolabile.O processamento e armazenamento de alimentos tornou-se imperativo para suprir as necessidades quotidianas do ser humano. Assim, o uso de aditivos artificiais passou a ser obrigatório para diminuir as perdas de valor nutricional por alterações químicas, microbiológicas e enzimáticas, mantendo assim as características do alimento processado por mais tempo. No entanto, o uso de aditivos artificiais tem sido bastante avaliado devido a vários estudos científicos que alertaram sobre os seus efeitos nocivos, que podem incluir problemas alergénicos, asma, entre outros. Esta situação leva à busca exaustiva por alternativas naturais capazes de servir o mesmo propósito. Para tal, a indústria alimentar iniciou essa missão através da extração de compostos naturais de microrganismos, animais, plantas ou de bio resíduos/desperdício alimentar. De facto, na indústria alimentar, diversos setores produzem grandes quantidades de resíduos, como por exemplo na produção de figos, que podem ser úteis para a recuperação de compostos bioativos para atuar como conservantes naturais. Os figos, por exemplo, são conhecidos pela sua riqueza em minerais e nutrientes e, por isso, o seu consumo aumentou significativamente, levando também à inevitável produção de bioresíduos que incluem folhas de figueira. Assim, no presente trabalho, foram exploradas folhas de figueira de cinco variedades diferentes, nomeadamente Dauphine, Longue d'Aout, Bourjassote Noire, Marseille e Pasteliere. Estas variedades foram analisadas relativamente ao seu perfil fenólico por HPLC-DAD-ESI- MS, bem como as suas bioatividades, nomeadamente propriedades antioxidantes pelos métodos de TBARs e CAA, antimicrobianas pelo ensaio de microdiluição, anti-inflamatórias utilizando macrógafos de rato e citotóxicas pelo método da sulforrodamina B. A extração dos compostos fenólicos foi otimizada pela metodologia de superfície de resposta e realizada por maceração dinâmica e extração assistida por ultrassons, sendo a sua determinação feita pelo ensaio de Folin ciocalteu. Finalmente, os extratos obtidos nas condições ótimas de extração pela tecnologia de ultrassons, utilizada por ser mais rápida, com um custo mais baixo, foram misturados de forma a analisar possíveis efeitos sinérgicos. Quando avaliada a atividade antioxidante dos extratos de folhas em conjunto, esta foi mais forte, já que a menor EC50 registrada para Bn (0,23 ± 0,01 mg/mL), e para a mistura foi EC50 de 0,12 ± 0,01 mg/mL. Além disso, a mistura apresentou resultados promissores quanto à atividade antimicrobiana, pois foram capazes de inibir todas as estirpes de bactérias e fungos testados. De realçar, que, quando em conjunto, os extratos revelaram atividade contra Pseudomonas aeruginosa com valor de CMI de 10 mg/mL. Como os extratos não apresentaram toxicidade na linha celular PLP2 com GI50>400 μg/mL, estes foram incorporados em duas formulações de compota de figo (com e sem mel), de forma a atuarem como conservantes naturais. Os produtos finais foram avaliados quanto às suas propriedades físicas (cor, textura, aw e pH), perfil nutricionais (humidade, cinzas, gordura por soxhlet, proteína pelo método kjeldahl, hidratos de carbono e energia), e químico, como os açúcares livres por HPLC-RI e ácidos gordos por GC-FID, e aindacarga microbiana. Após o processo de cocção, as diferentes propriedades foram avaliadas em duas temperaturas de incorporação (80°C e 50°C), de forma a determinar a eficiência dos extratos desenvolvidos e a sua estabilidade nos produtos finais. A compota de figo com baixo teor de açúcar incorporada com extratos conservantes naturais obtidos a partir de folhas de figueira, não revelou alterações na aparência geral das compotas. Em relação às propriedades nutricionais e químicas, as formulações apresentaram baixo teor de açúcar, baixo teor de proteína, alta quantidade de hidratos de carbono, e baixo teor de ácidos gordos (ácido palmítico como composto majoritário). Além disso, as diferentes temperaturas de incorporação não apresentaram alterações discerníveis ao longo do tempo, implicando que as moléculas de interesse presentes nos extratos não são termolábeis.European Regional Development Fund (ERDF) through the Competitiveness and Internationalization Operational Program for financial support to the project 100% Figo (POCI-01-0247- FEDER-064977)

The use of specialty sorghums for expanded snack food processing

The physical, chemical, and antioxidant properties of extrudates prepared from specialty tannin sorghum (CSC3xR28) and Tx430 black sorghums were evaluated. White food type sorghums (ATx631xRTx436) and commercial corn meal were also extruded. Sorghums were extruded as whole kernels or cracked (broken) kernels through a Maddox MX-3001 high-friction extruder. Cracked sorghum fortified with bran (0 -50%) derived from decortication or roller-milling were also extruded. Tannin sorghums extruded similarly to white food-type sorghums, with very little difference in extrudate quality. Cracking the sorghums produced lower feed rates, higher specific mechanical energy (SME) and extrudates that were less dense, more expanded, and softer than whole kernel extrudates. Whole and cracked sorghum materials had feed rates similar to corn meal, but lower SME. Corn meal extrudates were less dense, more expanded, and softer than sorghum extrudates. Cracked and whole black sorghum extrudates were less expanded than hi-tannin and white sorghum extrudates, due to the black sorghum's soft endosperm and thick, fibrous pericarp. With increased fiber, all extrudates had decreased SME and expansion, with increased bulk density and breaking force with the addition of bran. These effects, were more pronounced in extrudates containing decorticated bran vs. roller-milled bran. The decorticated bran had smaller particle size, higher density, lower endosperm content, and greater dietary fiber content than roller-milled bran. Also, increases in dietary fiber content in the extrudates were strongly correlated to increases in bran fortification in the raw feed stock. Tannin and black bran extrudates showed increased phenol, tannin (high-tannin), and antioxidants where bran was added. Phenols, tannins, and antioxidants in tannin extrudates ranged between 10.3-30.9 mg GAE/g, 7.1-55.2 CE mg/g, and 68.3-212.2 umol TE/g, respectively. Phenols and antioxidant activity in black sorghum extrudates ranged from 4.2 -7.8 mg GAE/g and 39.7 - 73.3 umol TE/g, respectively. Specialty tannin and black sorghums can be used to produce extruded snacks high in fiber and antioxidant activity. Optimum product characteristics, along with nutraceutical benefits, will need further determination

Boysenberry pomace as a source of antioxidant and dietary fibre in an extruded products

Boysenberry, a Rubus hybrid (R.ursinus × R.idaeus), was processed to acquire its pomace. Pomace was used to prepare extruded breakfast cereal products with maize and rice bases. In total 8 types of products were made: maize and rice extrudates with 4 levels of pomace substitution (control, 5 %, 10 % and 15 % (w/w) pomace mix). Each of the products was analysed for its physio-chemical, textural, availability of carbohydrates for digestion and antioxidants activity. The expansion of the products decreased significantly (p < 0.05) with an increase of pomace substitution. There was no distinct linear trend for the other properties such as moisture, crispiness and hardness for maize products. Although, in the case of rice products, crispiness appeared to decrease and moisture increased with increasing levels of pomace in the products. No significant difference was observed with the hardness of the products, the mean hardness of the products ranged from (2981 g – 3241 g). L*a*b* colour analysis was used to calculate chroma and hue angles for each of the products and raw mixes. Colour of the products tended to darken as the replacement with pomace increased. Mean L* value of pomace was 19.55 which is darker in appearance, whereas mean L* values for control maize and rice were 96.38 and 96.35 and was whiter in apperance. In vitro starch hydrolysis of the extruded products showed that the inclusion of the pomace to the extruded products significantly reduced the rate of sugar hydrolysis. The area under the curve (AUC) significantly decreased with the increase of pomace contents in extruded products, which indicate a potential glycaemic reducing action. The inclusion of pomace in extruded products significantly increased the product’s total phenolic content and antioxidant activity. The extrusion process significantly decreased the antioxidant activity of extruded products in comparison to its raw mixes, although extruded product was able to retain an apprecable level of antioxidant activity. Extruded products containing 15 % pomace (w/w) showed 300 % surge in the antioxidant activity when compared to the control for both maize and rice. This research illustrates that the introduction of boysenberry pomace to extruded products was able to decrease potential glycaemic action and increased antioxidant activity of the extruded products

Membrane separation of bioactive lycopene from tomato juice

This thesis is a study of the concentration and purification of lycopene from tomatoes and tomato juice using membrane technology and solvent extraction. In the first part of the study, three polymeric ultrafiltration (UF) membranes (PCI?s FP 200, FP 100, and ES 404) were screened for lycopene concentration in a cross-flow pilot plant-scale membrane unit with tomato juice containing 10-11 mg lycopene/100g of tomato juice. PCI?s FP 200 membrane was the best in terms of flux with average of 155 LMH at 60?C and 50 psi TMP for a 4.5 X concentration process. The tomato concentrate obtained as retentate, contained 51.7 mg lycopene/100g sample. In the solvent extraction study, five solvents (ethanol, ethyl acetate, tetrahydrofuran, acetone, and isopropanol) were tested at ambient temperature as cosolvents with hexane for extraction of lycopene from the tomato concentrate obtained by UF. Ethanol:hexane (4:3) resulted in the highest recovery. Multiple extractions of the same tomato paste with fresh ethanol:hexane resulted in an all-trans-lycopene yield of 91% after 3 extractions at a solvent-to-solids ratio of 45 ml per g. Total recovery of carotenoids from the tomato concentrate was 58.8 mg carotenoids/100g tomato concentrate where all-trans-lycopene counted for 87.9%, ?-carotene for 4.9%, 13-cis-lycopene for 3.2%, 7-cis-lycopene for 2.2%, and unidentified lycopene cis-isomers for 1.7%. In the nanofiltration study, five polymeric membranes were screened with lycopene-hexane extracts. The DS 7 manufactured by Osmonics-Desal was the best in terms of flux, rejection and stability. The DS 7 membrane resulted in an average flux and rejection of 152 LMH and 72% respectively at 26.7oC and 400 psi when concentrating lycopene in hexane from 17.1 ?g/ml to VCR 5. Preliminary design calculations indicate a 5-stage nanofiltration system can recover 90.2% of the lycopene and could result in a final retentate stream with 157 mg/l lycopene or more and a permeate stream with as low as 3.6 mg/l lycopene that can be recycled to the extraction stage. Economic calculations show that the industrial application of membrane technology for recovering lycopene is promising and profitable