Journal Articles

Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915

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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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    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.