Influence of caramel and molasses addition on acrylamide and 5-hydroxylmethylfurfural formation and sensory characteristics of non-centrifugal cane sugar during manufacturing.

BACKGROUND: The aims of this study are to (i) evaluate the effects of color enhancers, caramel (C) and molasses (M), on acrylamide and 5-hydroxylmethylfurfural (HMF) formation in non-centrifugal cane sugar (NCS) and to (ii) perform nine-point hedonic scale and evaluation of sensory attributes, encompassing the appearance, flavor, texture and aftertaste, by 71 consumers on NCS, NCS_C, and NCS products made with a blend of molasses and sugar (NCS_MS) and steam processing (NCS_S). RESULTS: With the addition of molasses and caramel at the maximum allowable level of 5 g kg-1 in sugarcane juice, significantly greater acrylamide or HMF did not accumulate in NCS_C and NCS_M during the thermal manufacturing process, while color values of NCS_C significantly changed (P < 0.05). The increases in acrylamide and HMF contents were influenced by pH because they were produced by the Maillard reaction. Hedonic responses showed that NCS_MS was rated with the highest score for overall acceptance, whereas NCS_S, with the lowest content of acrylamide, exhibited the lowest score for every attribute. In addition, the appearance acceptance score of NCS_C was significantly higher than that of NCS (P < 0.05). Significant differences were also found between NCS and NCS_C in the frequency of 9 of 16 items with which consumers selected to characterize the appearance in a check-all-that-apply questionnaire (P < 0.05). CONCLUSIONS: The association between hedonic evaluations and sensory profiles in visual attributes of NCS_C indicated that caramel could be a promising addition in Maillard reaction-mitigated NCS products to improve consumer preferences through color strengthening without safety concerns. © 2020 Society of Chemical Industry.

Selective Hydrogenation of 5-Hydroxymethylfurfural to 2,5-Dimethylfuran Over Popcorn-Like Nitrogen-Doped Carbon-Confined CuCo Bimetallic Catalyst.

A new type of biomass-based liquid fuel, 2,5-dimethylfuran (DMF), has attracted significant attention owing to its unique physical properties and carbon neutrality. It can be obtained from the hydrogenation of 5-hydroxymethylfurfural (HMF), an important biomass platform compound. In this study, we developed a nitrogen-doped carbon-confined CuCo bimetallic catalyst with a popcorn-like structure for the selective hydrogenation of HMF with high efficiency and adequate stability. Under optimized conditions, 100% HMF conversion and 93.7% DMF selectivity were achieved. The structure of the catalyst was characterized using XRD, XPS, SEM, and TEM. It was observed that carbon spheres, which were covered by nitrogen-doped carbon nanotubes, uniformly formed, while metal particles were confined in the nitrogen-doped carbon nanotubes. The popcorn-like structure exhibited a larger surface area and provided more contact sites, while the confined metal particles were the main active sites. The synergistic effect between Cu and Co was beneficial for DMF selectivity.

Dehydration of Glucose to 5-Hydroxymethylfurfural Using Nb-doped Tungstite.

Dehydration of glucose to 5-hydroxymethylfurfural (HMF) remains a significant problem in the context of the valorization of lignocellulosic biomass. Hydrolysis of WCl6 and NbCl5 leads to precipitation of Nb-containing tungstite (WO3 ⋅H2 O) at low Nb content and mixtures of tungstite and niobic acid at higher Nb content. Tungstite is a promising catalyst for the dehydration of glucose to HMF. Compared with Nb2 O5 , fewer by-products are formed because of the low Brønsted acidity of the (mixed) oxides. In water, an optimum yield of HMF was obtained for Nb-W oxides with low Nb content owing to balanced Lewis and Brønsted acidity. In THF/water, the strong Lewis acidity and weak Brønsted acidity caused the reaction to proceed through isomerization to fructose and dehydration of fructose to a partially dehydrated intermediate, which was identified by LC-ESI-MS. The addition of HCl to the reaction mixture resulted in rapid dehydration of this intermediate to HMF. The HMF yield obtained in this way was approximately 56 % for all tungstite catalysts. Density functional theory calculations show that the Lewis acid centers on the tungstite surface can isomerize glucose into fructose. Substitution of W by Nb lowers the overall activation barrier for glucose isomerization by stabilizing the deprotonated glucose adsorbate.

Heterogeneous catalyst-assisted thermochemical conversion of food waste biomass into 5-hydroxymethylfurfural.

A novel thermochemical conversion route has been developed that yields 5-hydroxymethylfurfural (HMF) from food waste biomass (FWB) in the presence of a heterogeneous catalysts (zirconium phosphate (ZrP)). The ZrP catalyst was prepared by precipitation followed by calcination at 400 (ZrP-400) and 600 °C (ZrP-600) and was characterized by SEM, XRD, XPS, N2 sorption and NH3-TPD. The optimized reaction conditions were identified to maximize HMF yield by varying the type of catalyst, the catalyst loading and the reaction time. The highest HMF yield achieved was 4.3%. On average 33% higher yield for ZrP-600 was obtained compared to that for ZrP-400, which might be due to higher number of acid sites on ZrP-600. The ZrP catalyst was easily regenerated by thermal treatment and showed stable activity upon its reuse. Preliminary calculations of the "minimum selling price" of HMF suggest that it is economically attractive to make this industrially-relevant chemical from FWB.

Establishment and assessment of a novel cleaner production process of corn grain fuel ethanol.

An integrated corn ethanol-methane fermentation system was proposed to solve the problem of stillage handling, where thin stillage was treated by anaerobic digestion and then reused to make mash for the following ethanol fermentation. This system was evaluated at laboratory and pilot scale. Anaerobic digestion of thin stillage ran steadily with total chemical oxygen demand removal efficiency of 98% at laboratory scale and 97% at pilot scale. Ethanol production was not influenced by recycling anaerobic digestion effluent at laboratory and pilot scale. Compared with dried distillers' grains with solubles produced in conventional process, dried distillers' grains in the proposed system exhibited higher quality because of increased protein concentration and decreased salts concentration. Energetic assessment indicated that application of this novel process enhanced the net energy balance ratio from 1.26 (conventional process) to 1.76. In conclusion, the proposed system possessed technical advantage over the conventional process for corn fuel ethanol production.