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    Development of Two Types of Isotonic Beverages with Functional Attributes Using Natural and Synthetic Ingredients
    (Faculty of Science, University of Peradeniya, Sri Lanka, 2024-04-23) Kariyawasam KP; Somaratne GM; Roy D; Silva DD; Weththasinghe WAOW; Sandanika DWN
    Isotonic drinks maintain a balance of salt and sugar concentrations similar to that of the human body, aiding in the rapid replacement of lost fluids during dehydration. Although the availability of isotonic beverages in the Sri Lankan market is limited, this segment is experiencing rapid growth on the global stage, with numerous brands marketing their products. Moreover, it is especially advantageous to create isotonic beverages tailored to tropical country consumers, given their ability to effectively replenish lost fluids due to dehydration. This study seeks to develop economically viable and commercially feasible formulations of isotonic drinks that cater to the preferences of Sri Lankan consumers, utilizing a combination of synthetic and natural ingredients. In the realm of natural isotonic beverages, coconut water and bee honey serve as excellent sources of electrolytes and sugar, respectively. Following osmolality and sensory evaluations, the chosen samples underwent further analysis to determine their mineral content and physicochemical characteristics. These developed formulations fall within the prescribed ranges for osmolality (270-330 mOsm/kg) and sodium content (460-1150 mg. L-1), aligning with international standards for isotonic beverages. In conclusion, the devised formulas successfully adhere to international specifications for isotonic beverages. The abundant potential of coconut water and bee honey in Sri Lanka with wide availability as valuable sources of minerals and energy for crafting isotonic drinks is evident.
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    Impact of protectant uptake on the shelf-life of dried Lacticaseibacillus rhamnosus
    (Elsevier, 2022-01) Priour S; Welman A; Singh H; Ellis A
    To improve the survival of dried probiotics, it is advised to expose the bacteria to protectants prior to processing, allowing equilibration of internal solutes. However, optimal conditions for this exposure remain unclear. This study examined solute uptake by Lacticaseibacillus rhamnosus HN001 (formally known as Lactobacillus rhamnosus HN001) at 4 °C and 20 °C, over exposure times of 0–240 min. The cells were exposed to hyperosmotic solutions of glucose and sucrose, two potential protective sugars, which are metabolisable and have different molecular weights. Sugar uptake was analysed through HPLC, while the impact on cell viability after freeze-drying was examined at 30 °C and 40 °C. The interactions between cell biomolecules and sugars were examined using Nano DSC. Results showed that the sugars were rapidly taken up by the cells, independent of temperature. At 20 °C, glucose was readily metabolised, eventually resulting in loss of cell viability during storage. Conversely, the Nano DSC study revealed interactions between the cells and sucrose, potentially providing some explanation as to the stability of the cells. In conclusion, sugar type and exposure temperature were shown to exert a significant effect on the viability of Lacticaseibacillus rhamnosus. Nano DSC is a promising technique to understand the protectant and cells’ interactions.
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    The Effect of a 14-Day gymnema sylvestre Intervention to Reduce Sugar Cravings in Adults
    (MDPI (Basel, Switzerland), 2022-12-12) Turner S; Diako C; Kruger R; Wong M; Wood W; Rutherfurd-Markwick K; Stice E; Ali A
    Gymnemic-acids (GA) block lingual sweet taste receptors, thereby reducing pleasantness and intake of sweet food. Objective: To examine whether a 14-day gymnema-based intervention can reduce sweet foods and discretionary sugar intake in free-living adults. Healthy adults (n = 58) were randomly allocated to either the intervention group (INT) or control group (CON). The intervention comprised of consuming 4 mg of Gymnema sylvestre containing 75% gymnema acids, a fibre and vitamin supplement, and an associated healthy-eating guide for 14 days; participants in the CON group followed the same protocol, replacing the GA with a placebo mint. Amount of chocolate bars eaten and sensory testing were conducted before and after the 14-day intervention (post-GA or placebo dosing on days zero and 15, respectively). Food frequency questionnaires were conducted on days zero, 15 and after a 28-day maintenance period to examine any changes in intake of sweet foods. A range of statistical procedures were used to analyse the data including Chi square, t-test and two-way analysis of variance. Post dosing, INT consumed fewer chocolates (2.65 ± 0.21 bars) at day zero than CON (3.15 ± 0.24 bars; p = 0.02); there were no differences between groups at day 15 (INT = 2.77 ± 0.22 bars; CON = 2.78 ± 0.22 bars; p = 0.81). At both visits, a small substantive effect (r < 0.3) was observed in the change in pleasantness and desire ratings, with INT showing a slight increase while CON showed a small decrease over the 14-day period. No differences were found in the intake of 9 food categories between groups at any timepoint. There were no differences in consumption of low sugar healthy foods between visits, or by group. The 14-day behavioural intervention reduced pleasantness and intake of chocolate in a laboratory setting. There was no habituation to the mint over the 14-day period. This study is the first to investigate the effect of longer-term gymnema acid consumption on sweet food consumption outside of a laboratory setting; further research is needed to assess how long the effect of the 14-day intervention persists.
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    The dissolution of alpha lactose monohydrate : a mathematical model for predicting dissolution times : a thesis presented in partial fulfilment of the requirements for the degree of Masters in Biotechnology and Bioprocess Engineering at Massey University
    (Massey University, 1993) Lowe, Edwin Kenneth
    Commercially available lactose is generally available in the form of alpha lactose monohydrate. The dissolution of this is slow in comparison to other sugars due to lactose existing in solution as alpha and beta lactose. When alpha lactose monohydrate has dissolved up to the alpha lactose solubility limit, no more can dissolve until some of the alpha lactose in solution has mutarotated to beta lactose. This makes mutarotation and the solubility of alpha lactose the two main limiting factors in lactose dissolution. A variety of factors can affect the mutarotation rate and solubility of lactose. Temperature and pH affect both significantly. The effect of carbohydrates in solution on the solubility of alpha lactose is particularly important as it has been found that beta lactose inhibits the solubility of alpha lactose. Dissolution of alpha lactose may be considered to consist of three steps; surface disintegration from the crystal, dissolution into the bulk of solution, and mutarotation of alpha to beta in solution. Attempts to model this process have previously been unsuccessful. For dissolution to total lactose concentrations above the alpha lactose solubility limit, it was found that the effect of beta lactose on the solubility of alpha lactose had a significant effect on the dissolution of lactose. For dissolution to total lactose concentrations below the alpha lactose solubility limit, it was found that the surface disintegration reaction was significant, particularly at low temperatures. A model was developed for predicting the dissolution of alpha lactose. This was found to compare well to experimental results for both single size and mixed crystal size lactose. The model worked well in dissolutions with excess lactose, dissolution to total lactose concentrations above and dissolutions below the alpha lactose solubility limit.
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    Thermal degradation of 1-amino-1-deoxyketoses and their role in flavour development : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University
    (Massey University, 1981) Birch, Edward John
    Sugars undergo caramelisation reactions at relatively high temperatures but when amino compounds are present, Maillard browning reactions are possible and these occur under less severe conditions. The reaction conditions and the basic character of the amino compounds determine the range of flavour compounds formed. The first step during Maillard browning is the condensation of a reducing sugar with an amine to form a glycosylamine and this compound may then undergo the Amadori rearrangement to form a 1-amino-1-deoxyketose. The pyrolysis of two 1-amino-1-deoxyketoses (1-deoxy-1-glycino-D-fructose and 1-β-alanino-1-deoxy-D-fructose) was studied in this investigation to examine their participation in a low energy route to aroma formation. Thermal analysis and parallel chemical investigations showed that the formation of these Amadori compounds facilitates the thermal degradation of their sugar and amino acid moieties. In addition increased quantities of various aroma compounds are produced, compared with the controls. In particular, the toxic compound protoanemonin is formed and a degradation pathway leading to its production is proposed. Most of the work involving the elucidation of degradation pathways during Maillard browning have involved studies in aqueous systems. Browning reactions between glucose and amino acids were also observed during heating in the dry-state in this study. These reactions are very vigorous once initiated and this precluded the study of a glucose plus amino acid control by the techniques used to study the pyrolysis of the 1-amino-1-deoxyketoses. Such reactions occur at temperatures below those required for the thermal degradation of the corresponding Amadori rearrangement compound thus questioning the involvement of these compounds in the lowest energy thermolysis pathway in the absence of moisture. The results of experiments designed to investigate the role of Amadori compounds during the browning of sugar-amino acid systems in the dry-state demonstrated however that the reactions reported to occur in aqueous systems can also account for the dry-state processes at temperatures up until the spontaneous decomposition of the 1-amino-1-deoxyketose can occur. That the 1-amino-1-deoxyketose does not brown by itself or in the presence of glucose as readily as a glucose plus amino acid system is presumably a basicity effect. The stronger base (the amino acid) may promote a solid-state enolisation of the glucose and hence initiate browning at a somewhat lower temperature. The results of these experiments also demonstrate the stability of the 1-amino-1-deoxyketoses and show that their formation is not a rate-limiting step during browning. In the third section of this thesis the effect of changing the amine moiety on the degradation pattern of 1-amino-1-deoxyketoses is assessed. Previous research has indicated that glucose by itself and Amadori compounds formed from weak primary bases degrade via an initial 1,2 enolisation step to form mainly 2-furaldehydes and pyrrole derivatives while 1-amino-1-deoxyketoses containing a strong basic moiety (usually formed from a secondary base) degrade via a 2,3 enol intermediate and give rise to fragrant caramel aroma compounds. Several 1-amino-1-deoxy-ketoses were prepared using primary and secondary bases covering a range of pkb values. These compounds were pyrolysed and their decomposition characteristics monitored by thermal analysis methods. Parallel analysis of the volatiles produced and a comparison of the results from previous investigations generally endorsed the reported hypotheses on the degradation of Amadori compounds. It was found that the structure of the base and functional groups present influenced the degradation phenomena as well as the basicity. The thermal decomposition of amino acid - derived Amadori compounds for instance, did not fit into the pattern of that observed for 1-amino-1-deoxyketoses derived from other bases. The amino acid influences the degradation traits by promoting 1,2 enolisation and charring rather than aiding 2,3 enolisation similar to bases of comparable pkb.
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    Low-Cost Sensor for Continuous Measurement of Brix in Liquids
    (MDPI AG, 25/11/2022) Jaywant SA; Singh H; Arif K
    This paper presents a Brix sensor based on the differential pressure measurement principle. Two piezoresistive silicon pressure sensors were applied to measure the specific gravity of the liquid, which was used to calculate the Brix level. The pressure sensors were mounted inside custom-built water-tight housings connected together by fixed length metallic tubes containing the power and signal cables. Two designs of the sensor were prepared; one for the basic laboratory testing and validation of the proposed system and the other for a fermentation experiment. For lab tests, a sugar solution with different Brix levels was used and readings from the proposed sensor were compared with a commercially available hydrometer called Tilt. During the fermentation experiments, fermentation was carried out in a 1000 L tank over 7 days and data was recorded and analysed. In the lab experiments, a good linear relationship between the sugar content and the corresponding Brix levels was observed. In the fermentation experiment, the sensor performed as expected but some problems such as residue build up were encountered. Overall, the proposed sensing solution carries a great potential for continuous monitoring of the Brix level in liquids. Due to the usage of low-cost pressure sensors and the interface electronics, the cost of the system is considered suitable for large scale deployment at wineries or juice processing industries.
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    Structural characterisation of methanogen pseudomurein cell wall peptide ligases homologous to bacterial MurE/F murein peptide ligases.
    (2022-09) Subedi BP; Schofield LR; Carbone V; Wolf M; Martin WF; Ronimus RS; Sutherland-Smith AJ
    Archaea have diverse cell wall types, yet none are identical to bacterial peptidoglycan (murein). Methanogens Methanobacteria and Methanopyrus possess cell walls of pseudomurein, a structural analogue of murein. Pseudomurein differs from murein in containing the unique archaeal sugar N-acetyltalosaminuronic acid instead of N-acetylmuramic acid, β-1,3 glycosidic bonds in place of β-1,4 bonds and only l-amino acids in the peptide cross-links. We have determined crystal structures of methanogen pseudomurein peptide ligases (termed pMurE) from Methanothermus fervidus (Mfer762) and Methanothermobacter thermautotrophicus (Mth734) that are structurally most closely related to bacterial MurE peptide ligases. The homology of the archaeal pMurE and bacterial MurE enzymes is clear both in the overall structure and at the level of each of the three domains. In addition, we identified two UDP-binding sites in Mfer762 pMurE, one at the exterior surface of the interface of the N-terminal and middle domains, and a second site at an inner surface continuous with the highly conserved interface of the three domains. Residues involved in ATP binding in MurE are conserved in pMurE, suggesting that a similar ATP-binding pocket is present at the interface of the middle and the C-terminal domains of pMurE. The presence of pMurE ligases in members of the Methanobacteriales and Methanopyrales, that are structurally related to bacterial MurE ligases, supports the idea that the biosynthetic origins of archaeal pseudomurein and bacterial peptidoglycan cell walls are evolutionarily related.