Cristina de Lorenzo

Regulated deficit irrigation in super-high-density (SHD) olive orchards is a well-known strategy to save water and control plant vigor, without decreasing fruit or oil yield. As there is controversial information about its influence on virgin olive oil quality, a trial was conducted in five SHD olive orchards of Arbequina cultivar in different locations of central, east, north and northeast Spain under full irrigation (FI) and regulated deficit irrigation (RDI) treatments. RDI applied during phase II of fruit growing (40% of total needs) saves more than 20% of water on average, without reductions in olive fruit or extra virgin olive oil (EVOO) yield. No threshold of 3.5 MPa of stem water potential was crossed in any case. RDI modified sterols and the fatty acid profile of EVOOs but not phenols, quality parameters, or the sensory profile. Latitude, altitude, and yearly rainfall have a big impact on some compounds such as campesterol, oleuropein, or margaroleic or linolenic acids.

The total phenols in virgin olive oil are highly dependent on cultivar, but also on ripening stage and other agronomic factors. The focus of most studies on agronomic factors has been irrigation, while fertilization has received less attention. Most of the fertilization works find that nitrogen over-fertilization leads to a decrease in phenol contents in virgin olive oil (VOO) and extra virgin olive oil (EVOO), under rain-fed or irrigation management. Ortho-diphenols also decrease with high doses of nitrogen, with no effect on secoiridoids. Phosphorous has a minor effect on irrigated trees; while the role of potassium is controversial, with a lack of trials with calcium and micro-nutrients. Due to the great impact of the fertilization on the phenol content and quality of VOO, new research is necessary with focus aimed at different cultivars and agronomic factors.

The objective of this work was to evaluate the influence of irrigation and fertilization with nitrogen and potassium on the sterol and triterpene dialcohol contents in two trials of cv. Arbequina in super-intensive orchards in Madrid and Lleida (Spain), using a completely randomized block design. No significant differences in total sterols between deficit and full irrigation treatments were observed. Under very dry conditions, the sterol levels from fully irrigated trees were higher than from rain-fed treatments and the triterpene dialcohol erythrodiol+ uvaol content was lower in the irrigated treatments in Lleida. In the fertilizer trial with full irrigation, total sterols were higher in the two N treatments compared to the unfertilized one; while erythrodiol + uvaol decreased. The application of K fertilizer had no effect on total sterol or triterpene dialcohol contents. A proper fertilization and irrigation are vital to obtain high quality EVOOs that meet the regulatory range in sterol and erythrodiol + uvaol contents.

Rainfed olive groves have been traditionally tilled in order to reduce the competition for water and nutrients. In sloping Mediterranean olive groves, this practice leads to high erosion rates, resulting in a reduction in soil fertility. Cover crops have been employed as a sustainable olive grove management strategy, but previous studies found differences in their effect on fruit load and there is scarce information on their influence on the virgin olive oil (VOO) quality. The aim of this study is to evaluate the effect of different soil management strategies on olive and oil yield and VOO physicochemical and sensory characteristics in a rainfed olive grove (238 trees·ha⁻¹) of Cornicabra cultivar, the main in Central Spain. No effect of soil management was found in olive or oil yield along three cropping seasons. VOO quality was mainly influenced by the year, but slight differences were found in the driest year between the studied treatments. Small differences in fruit ripening, pigments, and several fatty acids as well as in sensory parameters were found.

In this work a methodology to evaluate the sensory properties of honeys has been developed. The sensory analysis was carried out by means of a quantitative descriptive analysis (QDA) method, based on several reference scales, for the coverage of the designed range for each descriptor. The peculiarity of this sensory analysis is that the reference scales have been constituted by common foodstuffs agreed upon by consensus of the panel. The main sensory attributes evaluated in the analyses were: adhesiveness, viscosity, bitterness, aroma, sweetness, acidity, color and granularity. Both the intensity and persistence of honey aromas have also been estimated, together with the classification of the identified aromatic attributes into different groups. The method was applied to 55 artisanal honeys from Madrid (Spain) with the following results: (i) the developed sensory profile sheet allowed a satisfactory description of Madrid honeys; (ii) correlations between sensory attributes of three broad groups of Madrid honeys were obtained and (iii) aroma persistence, sweetness, bitterness, color and granularity appeared as the main sensorial characteristics of honey with discrimination power between floral and honeydew honeys.

The present study analyzed the effect of dietary fat and strain on the fatty acid and cholesterol contents of eggs over a 20 month-period. Hy-line and Warren hens received three consecutive 7% lipid diets in which the basal constituents of the diet supplied 3% of the fats while the remaining 4% was composed of fats, oils or oleins added to progressively increase polyunsaturated fatty acid (PUFA) levels, while decreasing dietary levels of both saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA). In general, the percentages of most fatty acids in egg lipids were affected by changes in dietary lipids but not by the strain. Data suggest the existence of a dietary threshold for elaidic acid to appear in eggs. Mufa decreased and total PUFA increased throughout the study. The cholesterol egg content was higher at the animal fat plus soybean oil than at the animal fat or the olein plus soybean oil blend. Overall, results showed that changes in dietary lipids influenced fatty acid composition and hence atherogenic and thrombogenic indexes much more than the strain.

Sixty-seven Spanish honeys from different floral origins, nectars and honeydews, were examined for potential antimicrobial and antioxidant activities. Antioxidant capacities were determined in terms of their antiradical capacity using the stable free radical DPPH•. The bacterial species Micrococcus luteus and Staphylococcus aureus were used as the resistant microorganism in the antibacterial assays. The results showed that honeydew honeys presented higher antioxidant capacities than nectar honeys. On the other hand, honey capacity to inhibit Micrococcus luteus and Staphylococcus aureus was firstly evaluated by an agar diffusion method. Secondly, the active samples were tested with a spectrophotometic method to quantify their “non-peroxide” antimicrobial capacity to inhibit Staphylococcus aureus . We did not observed any relationship between the physicochemical parameters of the samples, and their ability to inhibit these microorganisms. The results obtained by the spectrophotometric method show that this method is easy and useful in the evaluation of the antibacterial capacity of honeys.

Twenty‐two honey samples from Spain have been assayed in relation to (1) their sensory and physicochemical characteristics; and (2) their radical‐scavenging capacity against the stable free radical DPPH. Sensory analysis has been carried out by means of descriptive profiling with a trained panel. In previous studies, a strong correlation of the physicochemical parameters, (1) net absorbance and (2) electrical conductivity, was observed, with the radical‐scavenging capacity. Interestingly, some correlations were also observed between the mentioned radical‐scavenging capacity and some sensory parameters. Statistical analysis showed that sensory parameters of bitterness and color were directly correlated with the honey antioxidant capacity, whereas the parameters sweetness and crystallization degree were negatively correlated. In terms of sensory appreciation, bitterness and dark color are sensory parameters indicative of the honey scavenging capacity, which is greater in dark honeys, mainly honeydews. PRACTICAL APPLICATIONS: The main weight of this work is devoted to the sensory analysis of honeys by the use of objective scales, and to study the relation between these appreciations with the antioxidant properties of artisanal honeys. The main practical application is to improve the knowledge of the consumer about honey, its characteristics and properties, in order to provide criteria for selection. The direct correlation established between some sensory parameters and the antioxidant capacity of honey may enable the consumer to have an idea about the antioxidant capacity of the product. So, the intake of darker and less sweet honeys, which have higher antioxidant activities, in combination with other natural and better‐known foodstuffs rich in antioxidants (fruit, vegetables, olive oil, red wine, among others), can be introduced in the frame of an adequate diet.