Melanoidins are formed in foods during processing through the Maillard reaction between carbohydrates and amino compounds. The aim of this study was to draw conclusions about the formation mechanism and the structure of melanoidins formed at low water contents and low temperatures. In the Maillard reaction of d-glucose and γ-aminobutyric acid at low water contents 3-deoxyglucosone is the most important intermediate. Therefore, we used the reaction of 3-deoxyglucosone with γ-aminobutyric acid or β-alanine as a simplified model system. The degradation of 3-deoxyglucosone and the color formation of the formed melanoidins were determined. In addition, the reaction mixture was analyzed with high-resolution mass spectrometry and a Kendrick analysis was applied. Oligomers consisting of up to four molecules of 3-deoxyglucosone and three amino acids and their respective dehydration products with furanoidic structure were detected. The melanoidin structure of C-C linked monomeric units postulated by Kroh et al. could be confirmed.

Storage stability of white beet sugar is an important factor determining the sugar quality. Due to color formation during storage the sugar color can exceed the quality criteria of the European council directive 2001/111/EC for white sugar. It is not possible to predict the color formation tendency of a white sugar lot at the time of its production. Also the source and the mechanism of color formation during storage are unknown. Color formation in general can be caused by several factors, which can be divided into external influences such as humidity and temperature during storage and internal causes such as contents of ash, polyphenols, mono-and oligosaccharides, and amino compounds. In this work, the effect of the above mentioned factors and the nature of the formed colorants were analyzed. Studies on the color distribution in sugar crystals were carried out and the nonsucrose compounds in the surface film were determined. The syrup film on the crystal surface contains the same compounds and in similar contents as thick juice. A correlation between the changes in the amino acid and monosaccharide content and the color formation was established, which shows that the Maillard reaction is responsible for the color development during storage of sugar.

In this study, α-dicarbonyl compounds consisting of a backbone with six carbon atoms resulting from the Maillard reaction of d-fructose with γ-aminobutyric acid were determined. The reaction was carried out under mild reaction conditions at 50 °C and water contents between 0 and 90%. A thus far unknown α-dicarbonyl compound was found as the main product in the first 24 h at water contents below 50%. After isolation of its stable quinoxaline derivative, it was possible to identify the compound as 2-deoxy-d- glycero-hexo-3,4-diulose (2-deoxyglucosone). For the first time, the four C6-α-dicarbonyl compounds, 1-deoxyglucosone, 2-deoxyglucosone, 3-deoxyglucosone, and 4-deoxyglucosone, could be identified in the Maillard reaction of a hexose at the same time. This indicates the formation of a 2,3-eneaminol from the Schiff base of d-fructose and the formation of 2-amino-2-deoxy-3-ketose as an alternative to the Heyns product.

BACKGROUND: Fermentative lactic acid (LA) production and downstream processing require the addition of amounts of base and acid, respectively, as additives. This study tested the Amberlite resins FPA 53 and CR 5550 for separating lactic acid from inorganic salt-ions introduced by additives usingwater or H2SO4 as eluent. Furthermore, recycling of additives as acid and base was investigated.RESULTS: Using FPA 53 and 12.5 mmol L-1 H2SO4, an almost complete separation of LA and salt-ions was achieved. The yield of LA was more than 90%, which is comparable with state-of-the-art methods. Salt-ions were concentrated by monopolar electro-dialysis and the concentrate was converted into 1.1mol L-1 NaOH and 0.8 mol L-1 HCl by bipolar electro-dialysis. The NaOH solutionwas further concentrated to 5.3mol L-1 and used in fermentation. The LA yield obtained of 0.8 g per g saccharose is highly comparablewith reference fermentation. Furthermore, itwas shown that the reuse ofHCl does not negatively influence downstream processing.CONCLUSION: This study presents a way to separate salt-ions and LA, and to reuse recovered salt-ions as additives. Outcomes are expected to contribute to the development of processes for the co-product free preparation of pure LA formulations to be used in poly(LA) production. (C) 2016 Society of Chemical Industry

Modern instrumental analytical methods for the determination of 13C/12C ratios are established to differentiate between metabolic products of C3 and C4 plants. Differentiation and identification of sucrose from pure beet (Beta vulgaris) and pure cane (Saccharum officinarum) are possible without doubt. Influenced by the worldwide hydrological cycle the determination of the isotope ratios of 2H/1H and 18O/16O as well as their variations provide information about geographical origin. Using samples of selected crystal cane sugar (CCS) with known origin, invert sugar syrups (ISS) as well as burnt sugar syrups (BSS) produced therefrom, the authenticity was determined. The speciality sugars ISS and BSS which were made from CCS could be identified as carbohydrates of C4 plants by using 13C/12C Isotope-Ratio Mass Spectrometry (IRMS). In combination with yeast fermentation of ISS and sugar separation from BSS and fermentation into ethanol as well as knowledge about production water, the C2-H/O isotope ratios of ethanol can theoretically determine the geographical origin of the sugars.

Renewable feedstock gain increasing attention in a time of rising oil prices and uncertainty about security of supply. Often those alternative resources do have high prices and processing costs. Fermentation processes are still of major significance in biotechnological processes. Sourcing cheap raw materials is a task of agricultural businesses. Apart from feedstock costs, energy and nutrients show a great impact on process economics. This actual study explores the potential of sugar beet thick juice and raw juice to act in a bifunctional manner, either as substrate or nutrient. Key finding of this studies are that even in absence of additional nutrients with raw juice lactic acid yields of up to 51,5% compared to 13,5% with thick juice and 2,4% with crystalline sugar were obtained. Even with raw juice an enentoermic purity of l(+)-lactic acid >98% could be achieved. The analytical comparison shows that raw juice can provide significant share of amino acids of a typical yeast extract addition while crystalline sucrose shows no contribution.

Biotechnological production of lactic acid has been studied in various ways, e.g. microorganisms, fermentation processes, down-stream processes, fermentation substrates, and fermentation nutrients. The problems for all processes still are high costs for feedstock and fermentation nutrients. The objective of this study is a general evaluation of sugar beet thick juice from Pfeifer & Langen GmbH & Co. KG, Germany as a substrate for lactic acid production. In a series of fermentation experiments the results based on thick juice were comparable to those obtained using cane raw sugar and even better than using conventional corn starch as a fermentation subtrate. The most important findings for a later technical application are the high volumetric productivity (up to 5.5g·L–1·h–1), and the optical purity of the lactic acid (>99% ee l-LA).