Teresa Gomes

Study of organic honey from the Northeast of Portugal

Concerns about traces of numerous toxic substances and authenticity have prompted consumer demand for honey that is certified as organic, based on strict ecological, natural principles and traceability. The present study aims to characterize organic honey samples (n = 73) from Northeast Portugal, with respect to floral nectar origin, physicochemical parameters and microbial safety. The phenols and flavonoids contents, often referred to as responsible for honey’s bioactive properties, were also assessed. All organic honey samples were classified as monofloral lavender (Lavandula sp.), exceeded in quality the international physicochemical standards and showed low microbiological counts (yeast, moulds and aerobic mesophiles), with negative results in respect to fecal coliforms, Salmonella and sulphite-reducing Clostridium spp. Correlation of the palynological, physicochemical and microbiological results is necessary to check the authenticity, quality and sanitation of honey. Although not required by international legislation, results of those assessments provide a complete outlook and elucidation of the organic honey’s properties, which could promote its valorisation.

Antioxidant activity and bioactive compounds of lettuce improved by espresso coffee residues

The antioxidant activity and individual bioactive compounds of lettuce, cultivated with 2.5-30% (v/v) of fresh or composted espresso spent coffee grounds, were assessed. A progressive enhancement of lettuces antioxidant capacity, evaluated by radical scavenging effect and reducing power, was exhibited with the increment of fresh spent coffee amounts, while this pattern was not so clear with composted treatments. Total reducing capacity also improved, particularly for low spent coffee concentrations. Additionally, very significant positive correlations were observed for all carotenoids in plants from fresh spent coffee treatments, particularly for violaxanthin, evaluated by HPLC. Furthermore, chlorophyll a was a good discriminating factor between control group and all spent coffee treated samples, while vitamin E was not significantly affected. Espresso spent coffee grounds are a recognised and valuable source of bioactive compounds, proving herein, for the first time, to potentiate the antioxidant pool and quality of the vegetables produced.

Optimization of mead production using Response Surface Methodology

The main aim of the present work was to optimize mead production using Response Surface Methodology. The effects of temperature (x₁: 20-30°C) and nutrients concentration (x₂: 60-120g /hL) on mead quality, concerning the final concentrations of glucose (Y₁), fructose (Y₂), ethanol (Y₃), glycerol (Y₄) and acetic acid (Y₅), were studied. Twelve operational conditions were tested. No delays and moods were observed during fermentations. The second order polynomial models determined produced satisfactory fittings of the experimental data with regard to glucose (R²=0.646, p=0.001), ethanol (R²=0.741, p=0.049), glycerol (R²=0.899, p=0.002), fructose (R²=0.902, p=0.033) and acetic acid (R²=0.913, p=0.001). The optimum extraction conditions determined in order to maximize the combined responses were 24°C and a nutrients concentration of 0.88g/L. The mead produced under these conditions had the following characteristics: ethanol concentration of 10.2%, acetic acid 0.54 g/L, glycerol 7.8 g/L, glucose 1.8 g/L and fructose 2.5 g/L. These values were in agreement with the predicted and were within the safe limit established for acetic acid and the recommended range for glycerol. Furthermore, the residual sugars concentration was also low, decreasing the possibility of occurring undesirable refermentations.

Influence of sweetness and ethanol content on mead acceptability.

Abstract Mead is a traditional alcoholic beverage obtained by fermenting mead wort; however, its production still remains frequently an empirical exercise. Different meads can be produced, depending on fermentation conditions. Nevertheless, to date few studies have been developed on factors that may influence mead quality. The main objective of this work was to study the influence of sweetness and ethanol content on mead acceptability. Different meads were produced with two sweetness levels (sweet and dry meads) and three ethanol contents (18, 20, 22% (v/v)), adjusted by brandy addition. Afterwards, meads acceptability was evaluated by sensory analysis through a consumers’ panel (n=108) along with chemical analysis by HPLC-RID of glucose, fructose, ethanol, glycerol and acetic acid. The sweet (75 gglucose+fructose/L) and dry (23 gglucose+fructose/L) meads presented glycerol contents equal to 5.10±0.54 and 5.96±0.95 g/L, respectively, that were desirable since glycerol improves mead quality. Low concentrations of acetic acid were determined (0.46±0.08 and 0.57±0.09 g/L), avoiding the vinegar off-character. Concerning sensory analysis, the alcohol content of mead had no effect on the sensory attributes studied, namely, aroma, sweetness, flavour, alcohol feeling and general appreciation. Regarding sweetness, the “sweet meads” were the most appreciated by the consumers (score of 5.4±2.56), whereas the “dry meads” (score of 2.7±2.23) showed low acceptability. In conclusion, this work revealed that sweetness is a sensory key attribute for mead acceptance by the consumers, whereas ethanol content (18 to 22% (v/v)) is not.

Endophytic and Epiphytic Phyllosphere Fungal Communities Are Shaped by Different Environmental Factors in a Mediterranean Ecosystem

The diversity and factors influencing fungal assemblages in phyllosphere of Mediterranean tree species have been barely studied, especially when endophytic and epiphytic communities are simultaneously considered. In this work, the endophytic and epiphytic fungal communities from olive tree phyllosphere were studied. This tree species is natural from the Mediterranean region and adapted to grow under adverse climatic conditions. The main objectives were to determine whether there are differences between both fungal communities and to examine whether different abiotic (climate-related) and biotic (plant organs) factors play a pivotal role in structuring these communities. Both communities differed in size and composition, with epiphytic community being richer and more abundant, displaying also a dominance of melanized fungi. Season was the major driver of community composition, especially of epiphytes. Other drivers shaping epiphytes were wind speed and temperature, while plant organ, rainfall, and temperature were the major drivers for endophytic composition. In contrast, canopy orientation caused slight variations in community composition of fungi, but with distinct effects in spring and autumn seasons. In conclusion, epiphytic and endophytic communities are not driven by the same factors. Several sources of variation undergo complex interactions to form and maintain phyllosphere fungal community in Mediterranean climates. Climatic parameters have influence on these fungal communities, suggesting that they are likely to be affected by climate changes in a near future.

Modeling the Endophytic Fungus Epicoccum nigrum Action to Fight the “Olive Knot” Disease Caused by Pseudomonas savastanoi pv. savastanoi (Psv) Bacteria in Olea europaea L. Trees

In this paper, a four-populations’ nonlinear mathematical model is introduced to analyze the interactions between two different microorganisms and the olive tree on which they reside. One such microorganism infects and ultimately kills the branches while the other one has a beneficial effect on the plant. We aim at devising a control strategy of the action of the pathogenic microorganism on the plant. To this end, the equilibrium points of the ecosystem are investigated. Feasibility and stability conditions of the equilibria are derived analytically. The numerical simulations show that the infection transmission rate and the disease-related mortality can deeply affect the spread of the disease. Some conditions for the disease eradication are investigated and suggestions are given for the implementation of suitable biological controls, such as pruning of the infected leaves.