Olive Oil By-products Research Articles

SUPPLY CHAINS FOR VALORIZATION OF OLIVE GROVE RESIDUES AND OLIVE OIL INDUSTRY BY-PRODUCTS: A REVIEW ON RESEARCH AND LITERATURE ON OLIVE BASED BIOECONOMY

The residual biomass produced in the olive sector is the result of the large quantity of olive groves and olive oil manufacturers that generate byproducts with a potentially high energy content. Until now, the disposal and management of pruning residues and olive oil by-products has generally represented disposal problems which lead to environmental problems rather than opportunities for additional revenue. In this context, this study aimed to define a roadmap for studies in Turkey to untap the potential of olive grove residues and olive oil industry by-products and residues, (i.e., olive tree prunings, olive leaves, olive pomace) that could be used to produce high-added value products in an integrated biorefinery or in a bioenergy power plant. This paper presents a review on recent research on the valorization of olive by-products in line with the circular economy principles and the bioeconomy strategy and presents the literature which applies to design and management of olive biomass supply chains. Main objective is to provide a conceptual framework for developing and deploying an effective bioeconomy utilizing olive prunings and olive oil industry byproducts conducting a preliminary review of the olive oil chain residues in Europe and Turkey comparatively, assessment of technical potentials, biomass supply costs and allocation of biomass collection sites and energy production facilities with different supply chain scenarios. Biomass resource assessment, biomass feedstock supply chain design and management, and logistics optimization require multidisciplinary and interdisciplinary approaches. They need to be carried out properly in order to execute efficient projects in energy generation from biomass and/or extracting bio-commodities in biorefineries. Turkish researchers have adequate research on valorization methods for olive based biomass resources, but their studies are limited on general biomass supply chain design and particularly no research has been conducted for olive biomass resources. Taking all the aforementioned into account, the author proposes to conduct further studies on a biomass energy project including design of a supply chain network for energy valorization of olive grove residues and olive oil industry by-products in line with the common practice and being inspired by the leading countries like Spain and Italy, which will both contribute to circular business concept development and renewable energy capacity increase.

Characterization, Sensory and Oxidative Stability Analysis of Vegetable Mayonnaise Formulated with Olive Leaf Vinegar as an Active Ingredient.

Development of novel food products represents a basic meeting point for health and business requirements. Mayonnaise sauce is well-suited to be a healthy and tasty dressing. In this study, mayonnaise was formulated by using unconventional ingredients, such as olive leaf vinegar (OLV), soybean/high oleic sunflower oil blend, and soymilk (as an egg substitute). An 18% alcoholic vinegar was used as the control sample. OLV is a rich source of bioactive substances, especially polyphenols and represents a possible way to enhance the olive oil by-product valorisation. For this new typology of vinegar an high level of phenolic compounds (7.2 mg/mL GAE), especially oleuropein (6.0 mg/mL oleuropein equivalent) was found. OLV mayonnaise had 57% fat, composed of 11%, 64%, and 23% saturated, monounsaturated, and polyunsaturated fatty acids, while linolenic acid was up to 1.7%. The phenol and oleuropein contents were 68 and 52 mg/100 g, respectively. Sensory panellists expressed a moderate overall acceptability for both samples but attested more distinctive and positive sensations for the colour, odour, and taste attributes of OLV mayonnaise. Finally, oxidative stability and shelf life were better in OLV mayonnaise than in the control. Specifically, the peroxide value remained low (around 4.5 meqO2/kg) after 12 months of storage at room and low (4 °C) temperatures.

Industrial drying for agrifood by-products re-use: Cases studies on pomegranate peel (Punica granatum L.) and stoned olive pomace (pâtè, Olea europaea L.)

The effect of industrial drying processes on phenols and polysaccharides of olive pomace (pâté) and pomegranate peel was studied, with the aim to re-use pomegranate and olive oil by-products. Pomegranate peel (Wonderful and G1 varieties) was oven-dried at different temperatures, taking into account peel thickness and size. Pâté was freeze-dried and oven dried at 50–110 °C, at lab scale; then, an industrial drying system (150 °C) was compared to freeze-drying. All dried samples were analyzed in terms of phenolic and polysaccharides compounds. Drying at room temperature of small pieces of pomegranate peel guaranteed the highest humidity removal and recovery of phenols. Sugar analysis, DLS and 1H NMR confirmed that polysaccharide fractions were not significantly affected by the highest drying temperatures (42 °C for pomegranate, 150 °C for pâté). The two drying procedures at large scale were suitable for avoiding degradation of phenols, maintaining the same profiles of the corresponding freeze-dried samples.

Consumption of yogurt enriched with polar lipids from olive oil by-products reduces platelet sensitivity against platelet activating factor and inflammatory indices: A randomized, double-blind clinical trial

Several studies have reported the positive cardio-metabolic effects of yogurt consumption. The addition of olive oil’s bioactive extracts into yogurt can result to a functional food with pleiotropic properties against cardiovascular diseases. A polar lipid extract of olive pomace (OOPLE) that contains platelet activating factor receptor (PAF-R) antagonists, has been stated not only to inhibit the development of atherosclerotic plaques in hypercholesterolemic rabbits but also to regress the already formed plaques. The present study aims to investigate the effect of the daily intake of an OOPLE-enriched low-fat yogurt, on the metabolic profile, ex vivo platelet aggregation and markers of thrombosis and inflammation, in healthy, mainly overweight volunteers. A randomized, three-arm, double-blind, placebo-controlled, parallel-group, 8 weeks duration, clinical trial was performed in apparently healthy adults (35–65 years old). Group A (control group) consumed at most one yogurt every two weeks, Group B (plain yogurt) consumed one serving of plain yogurt every day and Group C (enriched yogurt) consumed one serving of yogurt, enriched with OOPLE, daily. Enriched yogurt intake resulted in lower levels of IL-10 and to lower platelet sensitivity against PAF, compared to the other two groups (p-values<0.05), while no impact on energy intake, body weight, glucose and lipid metabolism was detected. Lower levels of IL-6 were observed only at 4 weeks enriched yogurt intake (p = 0.03) compared to plain yogurt. Intake of the enriched yogurt resulted in reduced PAF-induced platelet aggregation and suppression of IL-10 levels. NCT02259205.

Sensory evaluation and consumer response of fillets from seabream fed with lipids extracted from olive oil by-products

Sensory evaluation and consumer response of fillets from seabream fed with lipids extracted from olive oil by-products

NADES for food industry innovation: novel bioadditives based on olive oil byproducts

There is an urgent need for the replacement of synthetic food additives by natural-based ones. In this scenario the recovery of biocompounds from byproducts represents a huge opportunity for their application as bioadditives in food industry. Among bioactive compounds, phenolics are recognized for their biological properties, being excellent antioxidants, antimicrobials, dyes in food applications. In this work green technologies with Natural Deep Eutectic Solvents (NADES) were combined for phenolic extraction, mainly luteolin and hydroxityrosol, from olive pomace of different seasons and cultivars. Three different NADES and organic solvent were evaluated being the mixture composed of lactic acid, glucose and water (LGH) selected due to its highest performance for phenolic extraction. To support the potential application of olive pomace-LGH extract as functional ingredient or food additive, in vitro digestion was performed. Phenolic content, total anthocyanin, antioxidant capacity hydroxytyrosol (Hty) and luteolin (Lut) concentration were monitored during the different steps of the process. Recovery index for intestinal phase was 183% for Hty and 75% for Lut indicating a high stability during gastrointestinal process. Regarding anthocyanins, 43% remained available, revealing the potential of LGH when compared with other researches. Bioaccessibility evaluation of olive pomace-LGH extract contributes to novel bioadditives development.

A validated qualitative method using oleuropein as a robust biomarker to confirm ground black pepper (Piper nigrum L.) adulteration with olive (Olea europaea L.) by-products

Olive stone and olive pomace were first identified as black pepper adulterants at the end of the 19th century. Nowadays, there is a worldwide boom in olive oil consumption. The olive oil and table olive industry generate tremendous volumes of olive wastes and this is presenting fraudsters with significant opportunities to use olive oil by-products as bulking agents in other foods such as black pepper. Despite the development of analytical methods for black pepper (Piper nigrum L.) authentication, it has been difficult to both detect and identify the specific fraudulent addition of Olea europaea L. waste by-products to this well-known spice. As such, there is a need for the development of a targeted method to address this issue. In this study, a secoiridoid phenolic biomarker of olive oil by-products, oleuropein, was identified as a target for the development of a novel analytical method, coupling ASE®) extraction and LC-MS/MS analysis for the identification of phenolic compounds as biomarkers of black pepper adulteration with olive wastes. The described operating conditions were used for the quantitation of oleuropein in olive oil by-products as well as the qualitative detection and identification of oleuropein in black pepper as a proof of the presence of olive waste addition as a bulking agent. Oleuropein was detected and quantified in all the olive oil by-product samples, even those subjected to processes such as olive-pomace extraction with hexane and sterilisation with steam heat-treatment. The method was validated for the qualitative detection of oleuropein in black pepper with selectivity and specificity values equal to 1 for 1.5% of olive pomace addition. The proposed method is simple and automated, requiring no purification step and can be applied as a rapid routine analysis to arm the industry against this potential fraud.

Olive byproducts and their bioactive compounds as a valuable source for food packaging applications.

Among the most important agro-industrial activities in the Mediterranean basin, olive oil production has a high impact on the economy of many Mediterranean countries. However, olive oil extraction generates huge quantities of byproducts, including leaves, pomace residues, stones and wastewater, which have severe environmental impacts mainly because of their phytotoxicity and great organic content. Olive oil byproducts are regarded as inexpensive and abundant raw materials rich in bioactive compounds with high and varied health-related activities. Several phenolic compounds and terpenoids were recovered from olive byproducts using different conventional and advanced extraction methods due to their potential to be used in food, packaging, pharmaceutical, and cosmetic industries. Recently, the use of olive byproducts and their functional compounds to enhance the functional properties of packaging systems was investigated as a sustainable strategy for food preservation, fostering the sustainability of the olive-oil chain, and promoting circular economy. In this framework, the main goals of this review are to summarize the main bioactive compounds in olive byproducts, to review the main advancements in their extraction, purification, and characterization, and finally to discuss their applications in food packaging systems as well as safety-related aspects.

Olive Pomace and Pâté Olive Cake as Suitable Ingredients for Food and Feed.

Olive oil extraction generates several by-products that represent an environmental issue, mainly for Mediterranean countries where olive oil is mostly produced. These by-products represent an ecological issue for their phenolic components, such as oleuropein, hydroxytyrosol, and tyrosol. However, olive oil by-products can be treated and properly exploited in different fields for their health-promoting properties, and they represent great potential for the food and beverage, cosmetic, and pharmaceutical industries. Furthermore, recovery and treatment processes can contribute to efficient waste management, which can enhance the sustainability of the olive oil industry, and in turn, lead to relevant economic benefits. The solid waste, i.e., olive pomace, could be considered to be a suitable matrix or primary resource of molecules with high added value due to their high phenolic content. Olive pomace, at different moisture contents, is the main by-product obtained from two- or three-phase extraction systems. A commonly used centrifugal extraction system, i.e., a multiphase decanter (DMF), does not require the addition of water and can generate a new by-product called pâté or olive pomace cake, consisting of moist pulp that is rich in phenols, in particular, secoiridoids, without any trace of kernel. Although several reviews have been published on olive wastes, only a few reviews have specifically focused on the solid by-products. Therefore, the aim of the present review is to provide a comprehensive overview on the current valorization of the main solid olive oil by-products, in particular, olive pomace or pâté olive cake, highlighting their use in different fields, including human nutrition.

Phenolic Compounds and Triterpenes in Different Olive Tissues and Olive Oil By-Products, and Cytotoxicity on Human Colorectal Cancer Cells: The Case of Frantoio, Moraiolo and Leccino Cultivars (Olea europaea L.).

Phenolic and triterpenoid compounds of the olive tree are recognized as having a key role in health promotion, thanks to their multiple protective actions in humans. To expand the source of these bioactive compounds, the phenolic and triterpenoid profiles of leaf, branch, destoned fruit, destoned pomace, shell, seed, and extra virgin olive oil from the Frantoio, Leccino, and Moraiolo olive cultivars were simultaneously characterized by HPLC-DAD-MS. Overall, 43 molecules were quantitated and expressed on the obtained dry extracts. Oleuropein was mainly concentrated in branches (82.72 g/kg), fruits (55.79 g/kg), leaves (36.71 g/kg), and shells (1.26 g/kg), verbascoside (4.88 g/kg) in pomace, and nüzhenide 11-methyl oleoside (90.91 g/kg) in seeds. Among triterpenoids, which were absent in shells, the highest amount of oleanolic acid was found in olive leaves (11.88 g/kg). HCT-116 colorectal cells were chosen to assess the cytotoxicity of the dry extract, using the phytocomplex from Frantoio, which was the richest in phenols and triterpenoids. The IC50 was also determined for 13 pure molecules (phenols and terpenoids) detected in the extracts. The greatest inhibition on the cell’s proliferation was induced by the branch dry extract (IC50 88.25 μg/mL) and by ursolic acid (IC50 24 μM). A dose-dependent relationship was observed for the tested extracts.

Exploitation of virgin olive oil by-products (Olea europaea L.): phenolic and volatile compounds transformations phenomena in fresh two-phase olive pomace ('alperujo') under different storage conditions.

BACKGROUNDMuch effort has recently been spent for re‐using virgin olive oil by‐products as nutraceutical ingredients for human diet thanks to their richness in bioactive phenols, but their management is not easy for producers. We aimed to provide useful information for a better management of fresh olive pomace before drying, by studying the phenolic and volatile compounds transformations phenomena of fresh olive pomace stored under different conditions planned to simulate controlled and uncontrolled temperature conditions in olive oil mills.RESULTSThe evolution of the phenolic and volatile compounds was studied by high‐performance liquid chromatography‐diode array detector mass spectrometry (HPLC‐DAD‐MS) and headspace solid‐phase microextraction gas chromatography‐mass spectrometry (HS‐SPME‐GC‐MS). The phenolic profile varied rapidly during storage: the verbascoside content decreased about 70% after 17 days even at 4 °C, while the content of simple phenols such as hydroxytyrosol and caffeic acid increased over time. The low temperature was able to slow down these phenomena. A total of 94 volatile organic compounds (VOCs) were detected in the fresh olive pomace, with a prevalence of lipoxygenase (LOX) VOCs (78%), mainly aldehydes (19 490.9 μg kg−1) despite the higher number of alcohols. A decrease in LOX volatiles and a quick development of the ones linked to off‐flavors (carboxylic acids, alcohols, acetates) were observed, in particular after 4 days of storage at room temperature. Only storage at 4 °C allowed these phenomena to be slowed down.CONCLUSIONTo preserve the natural phenolic phytocomplex of fresh olive pomace before drying and to avoid off‐flavors development, storage in open containers must be avoided and a short storage in cold rooms (7–10 days) is to be preferred. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Bench Test of a Hydraulic Biofluid Based on Refined Pomace Oil

AbstractThis paper aims at investigating the possibility of replacing conventional hydraulic fluids with refined olive pomace oil added with a common food grade antioxidant, as hydraulic fluid for agricultural machinery. The fluid efficiency test is carried out using an experimental test rig based on a hydraulic system designed to apply severe work cycles (pressure values up to 40 MPa; temperatures up to 100 °C) to small oil volumes with the aim of strongly accelerating the ageing of the tested fluid. The fluid, added with 2 g kg−1 of antioxidant, apparently does not undergo any changes in chemical‐physical properties and maintains stable the technical performance of the test equipment during 530 h work cycle. This research has four different goals: i) to contribute to the circular economy, by using olive oil byproducts in agricultural environment; ii) to contribute to the reduction of environmental contamination by substituting petroleum products with natural biodegradable ones; iii) to contribute to avoid the presence of mineral products (such as saturated hydrocarbons, which could accumulate in human organs, and aromatic hydrocarbons, which are potentially genotoxic), as a residue in food products and in vegetable oils. iv) to identify alternative market possibilities for such a by‐product.Practical applications: The results of the study seem to indicate the possibility of using the olive pomace oil as hydraulic fluid, for example, in agricultural machinery, opening new market perspectives which would increase its added value.

A Real Case Study of a Full-Scale Anaerobic Digestion Plant Powered by Olive By-Products.

The anaerobic digestion plant studied in this paper is one of the first full-scale plants using olive oil by-products. This is a two-stage plant with a power of 100 kWe. Two tests were performed: the first on olive pulp and pitted pomace and the second on biomass consisting of 10% crushed cereal. In both cycles, the retention time was 40 days. The production of biogas was between 51 and 52 m3/h, with limited fluctuations. The specific production values of biogas indicate that a volume of biogas greater than 1 m3/kg was produced in both tests. The produced biogas had a methane percentage of about 60% and the specific production (over total volatile solids, TVS) of methane was of the order of 0.70 m3methane/kgTVS. FOS/Alk (ratio between volatile organic acids and alkalinity) was always lower than 1 and tended to decrease in the second digester, indicating a stable methanogenic phase and the proper working of the methanogenic bacteria in the second reactor. The concentration of incoming biomass TPC (total polyphenols content) can vary significantly, due to the seasonality of production or inadequate storage conditions, but all measured values of TPC, between 1840 and 3040 mg gallic acid kg−1, are considered toxic both for acidogenic and methanogenic bacteria. By contrast, during the process the polyphenols decreased to the minimum value at the end of the acidogenic phase, biogas production did not stop, and the methane percentage was high.

Olive Mill Wastewater as Renewable Raw Materials to Generate High Added-Value Ingredients for Agro-Food Industries

Olive oil production represents an agro-industrial activity of vital economic importance for many Mediterranean countries. However, it is associated with the generation of a huge amount of by-products, both in solid and liquid forms, mainly constituted by olive mill wastewater, olive pomace, wood, leaves, and stones. Although for many years olive by-products have only been considered as a relevant environmental issue, in the last decades, numerous studies have deeply described their antioxidant, anti-inflammatory, immunomodulatory, analgesic, antimicrobial, antihypertensive, anticancer, anti-hyperglycemic activities. Therefore, the increasing interest in natural bioactive compounds represents a new challenge for olive mills. Studies have focused on optimizing methods to extract phenols from olive oil by-products for pharmaceutical or cosmetic applications and attempts have been made to describe microorganisms and metabolic activity involved in the treatment of such complex and variable by-products. However, few studies have investigated olive oil by-products in order to produce added-value ingredients and/or preservatives for food industries. This review provides an overview of the prospective of liquid olive oil by-products as a source of high nutritional value compounds to produce new functional additives or ingredients and to explore potential and future research opportunities.

Antithrombotic properties of differently fed farmed gilthead sea bream: In vitro and in vivo studies

Background and Aims: During the last years, the replacement of fish oil, by plant oils in compounded fish feeds, is under investigation. Platelet-Activating Factor (PAF) is a potent inflammatory mediator implicated in atherosclerosis. PAF antagonists exist in olive oil by-products (OOP), and inhibit the development of atherosclerosis in animal models. Present work aims to evaluate the in vitro and in vivo antithrombotic properties of sea bream fed with the polar lipid extract from OOP enriched-diet (enriched fish; EF) versus sea bream fed with fish oil diet (conventional fish; CF).

Activities of platelet-activating factor (PAF) enzymes after daily consumption for two months of a yogurt enriched with natural origin PAF inhibitors

Background and Aims: Platelet-activating factor (PAF), a pro-inflammatory lipid mediator, plays a crucial role in the formation of the atherosclerotic plaque. Therefore, the inhibition of endothelium inflammation by nutraceuticals, such as PAF inhibitors, is a promising alternative for preventing cardiovascular diseases. The aim of the present study is to evaluate the impact of a new functional yogurt enriched with natural origin PAF inhibitors from olive oil by-products on PAF metabolism.

Neuroprotective Effect of Terpenoids Recovered from Olive Oil By-Products.

The neuroprotective potential of 32 natural extracts obtained from olive oil by-products was investigated. The online coupling of supercritical fluid extraction (SFE) and dynamic adsorption/desorption allowed the selective enrichment of olive leaves extracts in different terpenoids’ families. Seven commercial adsorbents based on silica gel, zeolite, aluminum oxide, and sea sand were used with SFE at three different extraction times to evaluate their selectivity towards different terpene families. Collected fractions were analyzed by gas chromatography coupled to quadrupole-time-of-flight mass spectrometry (GC-QTOF-MS) to quantify the recoveries of monoterpenes (C10), sesquiterpenes (C15), diterpenes (C20), and triterpenes (C30). A systematic analysis of the neuroprotective activity of the natural extracts was then carried out. Thus, a set of in vitro bioactivity assays including enzymatic (acetylcholinesterase (AChE), butyrylcholinesterase (BChE)), and anti-inflammatory (lipoxidase (LOX)), as well as antioxidant (ABTS), and reactive oxygen and nitrogen species (ROS and RNS, respectively) activity tests were applied to screen for the neuroprotective potential of these extracts. Statistical analysis showed that olive leaves adsorbates from SS exhibited the highest biological activity potential in terms of neuroprotective effect. Blood–brain barrier permeation and cytotoxicity in HK-2 cells and human THP-1 monocytes were studied for the selected olive leaves fraction corroborating its potential.

Bioactive Compounds in Waste By-Products from Olive Oil Production: Applications and Structural Characterization by Mass Spectrometry Techniques.

In recent years, a remarkable increase in olive oil consumption has occurred worldwide, favoured by its organoleptic properties and the growing awareness of its health benefits. Currently, olive oil production represents an important economic income for Mediterranean countries, where roughly 98% of the world production is located. Both the cultivation of olive trees and the production of industrial and table olive oil generate huge amounts of solid wastes and dark liquid effluents, including olive leaves and pomace and olive oil mill wastewaters. Besides representing an economic problem for producers, these by-products also pose serious environmental concerns, thus their partial reuse, like that of all agronomical production residues, represents a goal to pursue. This aspect is particularly important since the cited by-products are rich in bioactive compounds, which, once extracted, may represent ingredients with remarkable added value for food, cosmetic and nutraceutical industries. Indeed, they contain considerable amounts of valuable organic acids, carbohydrates, proteins, fibers, and above all, phenolic compounds, that are variably distributed among the different wastes, depending on the employed production process of olive oils and table olives and agronomical practices. Yet, extraction and recovery of bioactive components from selected by-products constitute a critical issue for their rational valorization and detailed identification and quantification are mandatory. The most used analytical methods adopted to identify and quantify bioactive compounds in olive oil by-products are based on the coupling between gas- (GC) or liquid chromatography (LC) and mass spectrometry (MS), with MS being the most useful and successful detection tool for providing structural information. Without derivatization, LC-MS with electrospray (ESI) or atmospheric pressure chemical (APCI) ionization sources has become one of the most relevant and versatile instrumental platforms for identifying phenolic bioactive compounds. In this review, the major LC-MS accomplishments reported in the literature over the last two decades to investigate olive oil processing by-products, specifically olive leaves and pomace and olive oil mill wastewaters, are described, focusing on phenolics and related compounds.

Consumption of Enriched Yogurt with PAF Inhibitors from Olive Pomace Affects the Major Enzymes of PAF Metabolism: A Randomized, Double Blind, Three Arm Trial

Platelet-activating factor (PAF), a proinflammatory lipid mediator, plays a crucial role in the formation of the atherosclerotic plaque. Therefore, the inhibition of endothelium inflammation by nutraceuticals, such as PAF inhibitors, is a promising alternative for preventing cardiovascular diseases. The aim of the present study was to evaluate the impact of a new functional yogurt enriched with PAF inhibitors of natural origin from olive oil by-products on PAF metabolism. Ninety-two apparently healthy, but mainly overweight volunteers (35–65 years) were randomly allocated into three groups by block-randomization. The activities of PAF’s biosynthetic and catabolic enzymes were measured, specifically two isoforms of acetyl-CoA:lyso-PAF acetyltransferase (LPCATs), cytidine 5′-diphospho-choline:1-alkyl-2-acetyl-sn-glycerol cholinephosphotransferase (PAF-CPT) and two isoforms of platelet activating factor acetylhydrolase in leucocytes (PAF-AH) and plasma (lipoprotein associated phospholipase-A2, LpPLA2). The intake of the enriched yogurt resulted in reduced PAF-CPT and LpPLA2 activities. No difference was observed in the activities of the two isoforms of lyso PAF-AT. In conclusion, intake of yogurt enriched in PAF inhibitors could favorably modulate PAF biosynthetic and catabolic pathways.

Inhibitory Effect of Olive Phenolic Compounds Isolated from Olive Oil By-Product on Melanosis of Shrimps.

Melanosis is an unsolved problem of the crustacean industry and the cause of great loss of value. This study investigates the effect of two potent, natural antioxidants isolated from olive waste (hydroxytyrosol, HT and 3,4-dihydroxyphenylglycol, DHPG) and three novel HT-derivatives containing selenium and sulfur (dihydroxytyrosyl diselenide, N-hydroxytyrosyl selenourea, and N-hydroxytyrosyl thiourea) on the prevention of melanosis in Atlantic ditch shrimp (Palaemonetes varians) during refrigerated storage. These results clearly demonstrate the positive inhibitory effect of DHPG and dihydroxytyrosyl diselenide on delaying melanosis in vivo, although this effect was not dose dependent. The effect was associated with a concomitant-inhibitory effect on tyrosinase activity in vitro. To our knowledge, so far no studies on the prevention of melanosis have been conducted on this small specie of shrimp which is available in large quantities at any time of the year at low cost. Studies with these promising compounds could then be extended to other more economically important species with a greater guarantee of success.