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The weaning time is a crucial period in the management of piglets. The risk of development of post-weaning diarrhoea (PWD) in piglets is high. PWD is the cause of serious economic losses in pig herds. Since 2006, the use of antibiotic growth promoters for prevention of diarrhoeal diseases in piglets has been banned. This measure also led to the investigation of alternative suitable feed supplements that would be reasonably efficient in protecting and sustaining animal health and performance. Various natural materials such as probiotics, prebiotics, organic acids, zinc and plant extracts have been tested as effective alternatives to antibiotics. Recently, owing to their high adsorption capacity, research efforts have been conducted on the application of natural clays and clay-based feed supplements. The purpose of this review is to summarize the effect of different alternative components as growth promoters on the health and performance of weaned and growing piglets.

Organic acids, such as malate, citrate and oxalate, have been proposed to be involved in many processes operating in the rhizosphere, including nutrient acquisition and metal detoxification, alleviation of anaerobic stress in roots, mineral weathering and pathogen attraction. A full assessment of their role in these processes, however, cannot be determined unless the exact mechanisms of plant organic acid release and the fate of these compounds in the soil are more fully understood. This review therefore includes information on organic acid levels in plants (concentrations, compartmentalisation, spatial aspects, synthesis), plant efflux (passive versus active transport, theoretical versus experimental considerations), soil reactions (soil solution concentrations, sorption) and microbial considerations (mineralization). In summary, the release of organic acids from roots can operate by multiple mechanisms in response to a number of well-defined environmental stresses (e.g., Al, P and Fe stress, anoxia): These responses, however, are highly stress-and plant-species specific. In addition, this review indicates that the sorption of organic acids to the mineral phase and mineralisation by the soil's microbial biomass are critical to determining the effectiveness of organic acids in most rhizosphere processes.

Introduction. Red and black currants are a valuable component of a healthy diet because they are an excellent source of ascorbic acid, anthocyanins and minerals. Materials and methods. Three red currant cultivars and eight black currant cultivars were evaluated in terms of fruit quality. Some selected physicochemical characteristics such as berry weight, dry matter, soluble solids, total sugars, titratable acidity and total anthocyanins were investigated. Total anthocyanin content was measured with the pH differential absorbance method while citric, malic, tartaric and ascorbic acid were quantified by a reversed-phase HPLC method. Sodium, calcium, magnesium, iron, manganese, chromium and zinc were determined by ICP-MS following a microwave digestion, while potassium content was determined by FAAS. Results. Significant differences in the physicochemical and mineral content were detected among the cultivars. The range of total anthocyanins of the tested samples was 12.14–22.06 mg·100 g-1 (red currants) and 116.17–287.78 mg·100 g-1 (black currants). Ascorbic acid content varied between 23.23–44.62 mg·100 g-1 (red currants) and 161.58–284.46 mg·100 g-1 (black currants). Citric acid was predominant in all studied black and red currant cultivars, followed by malic and tartaric acids. Black and red currants have rich mineral composition, especially potassium, calcium and magnesium. Black currant fruits were superior to red currants with regard to calcium and magnesium content. Introduction. Les groseilles et les cassis sont un élément précieux pour une alimentation saine car ils sont une excellente source d’acide ascorbique, d’anthocyanines et de minéraux. Matériel et méthodes. Trois cultivars de groseille et huit cultivars de cassis ont été évalués quant à la qualité de leurs fruits. Certaines caractéristiques physico-chimiques telles que le poids, la matière sèche, les solides solubles, les sucres totaux, l’acidité titrable et les anthocyanines totales des baies ont été étudiées. La teneur totale en anthocyanines a été mesurée par la méthode d’absorbance différentielle du pH tandis que les acides citrique, malique, tartrique et ascorbique ont été mesurés par la méthode de chromatographie liquide sous haute pression en phase inverse. Les éléments sodium, calcium, magnésium, fer, manganèse, chrome et zinc ont été déterminés par ICP-MS après une digestion au micro-onde tandis que la teneur en potassium a été déterminée par FAAS. Résultats. Des différences significatives de teneurs en éléments physico-chimiques et minéraux ont été détectées parmi les cultivars. La gamme des anthocyanines totales des échantillons examinés a été de 12.14–22.06 mg·100 g-1 (groseilles rouges) et 116.17–287.78 mg·100 g-1 (cassis). La teneur en acide ascorbique a varié entre 23.23–44.62 mg·100 g-1 (groseilles rouges) et 161.58–284.46 mg·100 g-1 (cassis). L’acide citrique a été l’acide prédominant dans tous les cultivars étudiés de groseille et de cassis; il a été suivi des acides maliques et tartriques. Les groseilles et les cassis ont une riche composition minérale, particulièrement en ce qui concerne le potassium, le calcium et le magnésium. Les teneurs en calcium et magnésium des cassis ont été supérieures à celles des groseilles rouges. Introducción. Las grosellas y las grosellas negras son un elemento preciado para una alimentación sana, dado que son una excelente fuente de ácido ascórbico, de antocianinas y de minerales. Material y métodos. Se evaluaron tres cultivares de grosella y ocho cultivares de grosella negra, en cuanto a la calidad de sus frutos. Se estudiaron ciertas características físico-químicas, tales como el peso de las bayas, la materia seca, los sólidos solubles, los azúcares totales, la acidez valorable y las antocianinas totales. Se midió el contenido total de antocianinas, mediante el método de absorbancia diferencial del pH, mientras que los ácidos cítrico, málico, tartárico y ascórbico se midieron mediante el método de cromatografía de líquidos de alta resolución en fase inversa. Los elementos sodio, calcio, magnesio, hierro, manganeso, cromo y cinc se determinaron mediante ICP-MS, tras una digestión en el micro-ondas, mientras que el contenido de potasio se determinó mediante FAAS. Resultados. Entre los cultivares, se detectaron diferencias significativas de contenidos de elementos físico-químicos y minerales. La gama de las antocianinas totales de las muestras examinadas fue de 12,14–22,06 mg·100 g-1 (grosellas rojas) y 116,17–287,78 mg·100 g-1 (grosellas negras). El contenido en ácido ascórbico varió entre 23,23–44,62 mg·100 g-1 (grosellas rojas) y 161,58–284,46 mg·100 g-1 (grosellas negras). El ácido cítrico fue el ácido predominante en la totalidad de los cultivares estudiados de grosella y de grosella negra; le siguieron los ácidos málicos y los tartáricos. Las grosellas y las grosellas negras tienen una composición mineral rica, particularmente en lo que se refiere al potasio, al calcio y al magnesio. Los contenidos de calcio y de magnesio de las grosellas negras fueron superiores que los de las grosellas rojas.

Organic acids (oxalic, citric, malic, and succinic) contents of Domat, Memecik and Uslu varieties of olives grown in Turkey were investigated using HPLC method. Organic acids were extracted from olives with water-methanol mixture solution 75:25 (v/v) and were analysed through KC-118 ion-exchange column using UV absorbance detector at 214 nm. The mobile phase was phosphoric acid (0.1%, w/v). The recovery values of the organic acids added into olive fruit samples were 92.8%, 98.75%, 110%, and 86% for oxalic, citric, malic, and succinic acids, respectively.

The effect of malolactic fermentation (MLF) on the flavour quality of cider was examined. Leuconostoc mesenteroides subsp. mesenteroides Z25 was used to start MLF taking place at 25 deg C for 12 days after the completion of alcoholic fermentation (AF) by Saccharomyces cerevisiae. Strain Z25 showed good activity in starting MLF of cider with 10% alcoholic concentration. The content of malic acid, whose high concentration gives negative organoleptic characteristics to the cider, dropped significantly from 4.0 g/l to 0.25 g/l via MLF. The concentration of lactic acid increased significantly from 0.99 g/l to 3.50 g/l, contributing to volatile acidity. The acetic acid content of the ciders was 0.74 g/l. Among 51 volatile compounds detected by GC-MS, higher alcohols, esters, and carbonyl compounds were formed in ciders through MLF. The total concentration of aromatic substances doubled compared to the controls. The occurrence of MLF started by strain Z25 enabled the cider containing more volatile compounds and an acceptable adjustment of organic acids. This is the first report on using L. mesenteroides subsp. mesenteroides strain Z25 to start the MLF of apple wine improving the flavour quality of the cider produced.

Nia30(145) transformants with very low nitrate reductase activity provide an in vivo screen to identify processes that are regulated by nitrate. Nia30(145) resembles nitrate-limited wild-type plants with respect to growth rate and protein and amino acid content but accumulates large amounts of nitrate when it is grown on high nitrate. The transcripts for nitrate reductase (NR), nitrite reductase, cytosolic glutamine synthetase, and glutamate synthase increased; NR and nitrite reductase activity increased in leaves and roots; and glutamine synthetase activity increased in roots. The transcripts for phosphoenolpyruvate carboxylase, cytosolic pyruvate kinase, citrate synthase, and NADP-isocitrate dehydrogenase increased; phosphoenolpyruvate carboxylase activity increased; and malate, citrate, isocitrate, and alpha-oxoglutarate accumulated in leaves and roots. There was a decrease of the ADP-glucose pyrophosphorylase transcript and activity, and starch decreased in the leaves and roots. After adding 12 mM nitrate to nitrate-limited Nia30(145), the transcripts for NR and phosphoenolpyruvate carboxylase increased, and the transcripts for ADP-glucose pyrophosphorylase decreased within 2 and 4 hr, respectively. Starch was remobilized at almost the same rate as in wildtype plants, even though growth was not stimulated in Nia30(145). It is proposed that nitrate acts as a signal to initiate coordinated changes in carbon and nitrogen metabolism.

An experiment was conducted to investigate the effect of various organic acid (OA) supplementation on phosphorus (P) and nitrogen (N) retention by rainbow trout fed low fishmealbased diets. Six experimental diets were formulated, and diet 0.5P was arranged as a positive control diet with 0.5% calcium phosphate and OP as a negative control without additional P. Diets CA and LA were supplemented with 1% citric (CA), and lactic (LA) acids, respectively, and diets MHA and LTE were supplemented with 1% methionine hydroxy analog (MHA) and 1% liquid trace elements (LTE), respectively. Fish fed CA and LTE showed similar growth to that of the positive control diet. P retention was lowest in the 0.5P group and was elevated with CA and LTE diets. Therefore, in this study it is suggested that it might not be necessary to supplement the low fishmeal-based diet of rainbow trout with P if certain organic acids such as CA are added.

The basic chemical characteristics of 22 quince genotypes and cultivars were determined: dry matter content, soluble solid content, the contents of organic acids, pectins, and mineral elements (nitrogen, phosphorus, potassium, calcium, and sodium). Quince fruits were harvested in the course of October and analysed at the stage of consumption ripeness after storage at 2 deg C and relative air humidity of 85%. The levels of pectins in fruits were high - the cultivar Hruskovita contained 3.51+/-0.19 g/100 g FW. The concentrations of vitamin C were also high, the cultivar Muskatova containing as much as 79.31+/-2.01 g/100 g FW. The affinity of chemical properties of the individual cultivars was expressed by means of cluster analysis and it was found out that there were no marked differences between pear-shaped (Cydonia oblonga subsp. pyriformis) and apple-shaped (Cydonia oblonga subsp. maliformis) forms of fruit.

Gas chromatograph/mass spectrometry (GC/MS) analysis was carried out to determine both the volatile and nonvolatile organic acids in kimchi during 60 days of fermentation at 10°C. Principal component analysis (PCA) was applied to differentiate the pre-defined organic acids and lactic acid bacteria (LAB) during fermentation. Acetic acid was observed as dominant, which was vigorously produced until the middle of fermentation. Lactic acid was the major non-volatile organic acid in the kimchi and was produced throughout fermentation. In contrast, malic acid content decreased sharply at the initial stage of fermentation. Colony forming units of LAB in the kimchi, such as Leuconostoc, Lactobacilli, Pediococci, and Streptococci, were measured on selective media. Populations of Leuconostoc and Lactobacilli increased exponentially over 7 days of fermentation, indicating acetic acid and lactic acid were mainly produced by Leuconostoc and Lactobacilli. PCA demonstrated that acetic acid, propionic acid, lactic acid, butanoic acid, malic acid, Leuconostoc, and Lactobacilli were major components that differentiated the kimchi according to fermentation time.

Biological soil disinfestation (BSD), or reductive soil disinfestation, achieved by amendment with organic materials such as wheat bran followed by flooding and covering the soil surface, has been used to control some soilborne diseases including Fusarium wilt and bacterial wilt of tomato. During a BSD treatment, accumulation of acetic acid and/or butyric acid was detected with high-performance liquid chromatography. Survival of Fusarium oxysporum f. sp. lycopersici or Ralstonia solanacearum was suppressed by these organic acids. Amendment of these organic acids into soil suppressed the survival of R. solanacearum at lower concentrations than the maximum detected in BSD treatment, indicating that production of these organic acids is one of the mechanisms of control. However, F. oxysporum f. sp. lycopersici in soil survived with the maximum concentrations of these organic acids achieved by BSD; thus, involvement of factors other than organic acids may be involved. [PUBLICATION ABSTRACT]