María A. Martín-Cabrejas

Characterization of Industrial Onion Wastes (Allium cepa L.): Dietary Fibre and Bioactive Compounds

The food industry produces a large amount of onion wastes, making it necessary to search for possible ways for their utilization. One way could be to use these onion wastes as a natural source of high-value functional ingredients, since onion are rich in several groups of compounds, which have perceived benefits to human health. The objective of this work is to gain knowledge of any differences between the different onion wastes obtained from industry and non-commercial bulbs to use them as food ingredients rich in specific compounds. The results showed that brown skin and top–bottom could be potentially used as functional ingredient rich in dietary fibre, mainly in insoluble fraction, and in total phenolics and flavonoids, with high antioxidant activity. Moreover, brown skin showed a high concentration of quercetin aglycone and calcium, and top–bottom showed high concentration of minerals. Outer scales could be used as source of flavonols, with good antioxidant activity and content of dietary fibre. However, inner scales could be an interesting source of fructans and alk(en)yl cystein sulphoxides. In addition, discarded onions (cvs Recas and Figueres) could be used as a good source of dietary fibre, and cv Recas also as a source of phenolics compounds.

Starch, Functional Properties, and Microstructural Characteristics in Chickpea and Lentil As Affected by Thermal Processing

Changes in starch, functional, and microstructural characteristics that occurred in chickpea and lentil under soaking, cooking, and industrial dehydration processing were evaluated. Available starch in raw legumes represented 57-64%, and resistant starch (RS) is a significant component. As a result of cooking, available starch contents of soaked chickpea and lentil were significantly increased (21 and 12%, respectively) and RS decreased (65 and 49%, respectively) compared to raw flours. A similar trend was exhibited by dehydration, being more relevant in lentil (73% of RS decrease). The minimum nitrogen solubility of raw flours was at pH 3, and a high degree of protein insolubilization (80%) was observed in dehydrated flours. The raw legume flours exhibited low oil-holding capacities, 0.95-1.10 mL/g, and did not show any change by thermal processing, whereas water-holding capacities rose to 4.80-4.90 mL/g of sample. Emulsifying activity and foam capacity exhibited reductions as a result of cooking and industrial dehydration processing. The microstructural observations were consistent with the chemical results. Thus, the obtained cooked and dehydrated legume flours could be considered as functional ingredients for food formulation.

Study of total fructan and fructooligosaccharide content in different onion tissues

The objective of this work was to determine the fructan and fructooligosaccharide (FOS) content of different onion tissues in order to evaluate the potential use of onion by-products from the food industry as a source of FOS and fructans. Assays with two methods were carried out to optimise the extraction procedure. The main FOS, namely kestose (GF2), nystose (GF3) and fructofuranosylnystose (GF4), were measured directly using standard sugars. The method for total fructans was based on enzymatic treatment (Novozym 230) of ethanolic/aqueous extract followed by determination of released fructose and glucose by HPLC. Data showed a clear predominance of GF2 in every onion tissue and no occurrence of highly polymerised fructans. The tissues richest in fructans were the fleshy layers, so that the outer two fleshy layers turn out to be the best onion by-product as a possible fructan source. © 2000 Society of Chemical Industry

Achievements and Challenges in Improving the Nutritional Quality of Food Legumes

Quality aspects of food crops have globally important market economic and health repercussions in the current climate of food security. Grain legumes have high potential for the nutritional quality improvement of foods, but limited data on manipulating seed quality is available as the primary focus has been hitherto on phenotypic and agronomic trait improvement. This has resulted in a lack of innovation and low attractiveness of legume food products that, with the emergence of novel food habits, have together contributed to reduced legume food consumption. This trend now needs to be challenged and circumvented. In this review we have assessed the key factors affecting the nutritional quality of legume seeds such as protein, starch, dietary fiber, natural antioxidant compounds and anti-nutritional factors. All have been reviewed with emphasis on how these components might influence consumer acceptance and functional properties of legume based food products. Biofortification approaches and technological processing are discussed as ways in which the nutritional value of legumes and their consumption might be enhanced. In order to increase consumption of grain legumes, we propose that efforts should concentrate on identifying nutritionally enhanced and genetically diverse germplasm, and on linking genetics with sensorial and processing quality. This will assist the development of breeding/selection tools for traits that determine consumer demand, facilitating the implementation of quality breeding objectives in legume breeding programs. Equally important, efforts should focus on developing attractive, convenient ready-to-eat and tasty legume-based food formulations, contributing to the diversification of healthier and more nutritional diets. As a result of such a targeted effort, legume cultivation and consumption could be enhanced leading to a reduction in both the global economic burden caused by malnutrition and associated chronic diseases, and the environmental impact of agriculture.

Evaluation of Phenolic Profile and Antioxidant Properties of Pardina Lentil As Affected by Industrial Dehydration

This study presents the effects of soaking, cooking, and industrial dehydration treatments on phenolic profile and also on antioxidant properties in Pardina lentil. HPLC-PAC and HPLC-MS (ESI) analysis identified a total of 35 phenolic compounds in raw and processed lentil flours, corresponding to catechins and procyanidins (69% of the total of identified phenolic compounds), flavonols (17%), flavones, and flavanones (5%), and hydroxybenzoic and hydroxycinnamic compounds (5 and 4%, respectively). During the industrial process, catechins and procyanidins, flavonols, flavones, and flavanones decreased, while hydroxybenzoic compounds exhibited an important increase. In addition, raw lentils showed high values of the antioxidant activity (66.97 μmol Trolox/g); although the thermal processing promotes decreased, the levels of antioxidant activity were still relevant. Thus, the significant occurrence of bioactive phenolic compounds along with the interesting antioxidant capacity of dehydrated lentil flours make them useful for daily inclusion in the human diet as ready-to-use for special meals to specific populations.

A novel antioxidant beverage for body weight control based on coffee silverskin

The present research aimed to add value to coffee silverskin by looking for new innovative applications. Formulation of novel beverages based on coffee silverskin for body fat reduction and body weight control was proposed. Conditions for beverage preparation were optimised. Data on chemical composition and sensorial quality of the new drink were acquired. Health benefits were evaluated in vitro and in vivo employing as animal model Caenorhabditis elegans. An antioxidant beverage containing physiological active concentrations of caffeine and chlorogenic acid for prevention body fat accumulation and possessing acceptable sensorial properties was obtained. Our findings support that the use of coffee silverskin for obtaining bioactive extract is an innovative way for revalorisation of coffee by-product.

Changes in nonnutritional factors and antioxidant activity during germination of nonconventional legumes

The present study describes the effects of germination on nonnutritional factors and antioxidant activity in the nonconventional legumes Vigna unguiculata (cowpea), Canavalia ensiformis (jack bean), Lablab purpureus (dolichos), and Stizolobium niveum (mucuna). Protease inhibitors and lectins were detected in raw legumes and were significantly decreased during the germination. Regarding total and individual inositol phosphates (IP5-IP3), important reductions of IP6 and high increases in the rest of inositol phosphates were also detected during this process. In addition, total phenols, catechins, and proanthocyanidins increased, accompanied by an overall rise of antioxidant activity (79.6 μmol of Trolox/g of DW in the case of mucuna). Germination has been shown to be a very effective process to reduce nonnutritional factors and increase bioactive phenolic compounds and antioxidant activities of these nonconventional legumes. For this reason, they could be used as ingredients to obtain high-value legume flours for food formulation.

Effect of sterilisation on dietary fibre and physicochemical properties of onion by-products

Food industries are forced to develop productions without secondary residues. Therefore, there is a considerable emphasis on the recovery, recycling and upgrading of wastes. The possibility has been suggested for the conversion of onion waste into food ingredients, but with a stabilisation treatment being necessary. The objective of this work was to study the effect of sterilisation on fibre fractions, fibre composition and physicochemical properties of onion by-products to evaluate the use of sterilised onion by-products as a source of fibre. Sterilisation produced insoluble dietary fibre decreases and soluble dietary fibre increases, improving the soluble:insoluble ratio. Uronic acids of insoluble dietary fibre were partly solubilised and losses of cellulose and Klason lignin were observed. Physicochemical properties slightly changed with sterilisation. Sterilised by-products showed less oil holding capacity, cation exchange capacity and swelling capacity than control ones, although their physicochemical properties were generally higher than those of cellulose. Therefore, sterilisation would be considered a good method to stabilise onion by-products to use as a potential dietary fibre ingredient.

Effects of gibberellic acid (GA3) on strawberry PAL (phenylalanine ammonia-lyase) and TAL (tyrosine ammonia-lyase) enzyme activities

Gibberellic acid (GA 3 ) treatments (30 and 60 μg litre -1 ) were applied to young plants (Fragaria ananassa cv Chandler). Fruits were harvested at various developmental stages (14, 21, 28 and 35 days from fruit set). Weight and size, phenolic compounds (total polyphenols and anthocyanins) and enzyme activities, phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) were determined. Our aim was to obtain detailed information about PAL and TAL activities related to the strawberry colour during development and ripening processes and to determine the effects of exogenous treatments of GA 3 on PAL and TAL activities. Exogenous treatments of GA 3 improve weight, size and colour of strawberry fruits, and affect PAL and TAL activities. We found that the anthocyanin content and PAL activity are enhanced by the exogenous treatment of GA 3 in the range of 30 μg litre -1 . However, with the higher GA 3 treatment, only the anthocyanin content is affected in that way. These findings suggest that gibberellic acid effect on PAL, TAL and ultimately anthocyanin enhancement is dosage related and saturation of the response occurs at 30 μg litre -1 .

Phenolic compounds in fruits and beverages consumed as part of the mediterranean diet: their role in prevention of chronic diseases

The objective of this review was to assess, based on human data, the role of phenolic compounds in selected plant foods consumed as part of the Mediterranean diet in the prevention of chronic diseases (CDs) like cardiovascular disease, cancer and neurodegenerative conditions. Fruits and vegetables are rich sources of phenolic compounds and based on scientific data it would be expected that their consumption, as part of the diet, would be responsible for their documented preventive role of chronic diseases. The results of the review of scientific literature on human clinical trials revealed that in some studies polyphenols exert a positive effect in the prevention of cardiovascular disease, essentially blood pressure and arterial dilation, certain types of cancer and neurodegenerative disorders. However, such effects are not consistent with other clinical studies in which no effect has been found. Therefore, the level of evidence for a beneficial effect in humans of phenols on the prevention of CDs is weak and need to be strengthened by additional studies addressing potential confounding factors, such as interaction of phenols with other bioactive substances in foods and potential pro-oxidant effects.