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Author: search.filters.author.McNabb WCSubject: search.filters.subject.Mathematical modelling

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    Global nutrient content embedded in food losses and waste: Identifying the sources and magnitude along the food supply chain
    (Elsevier Ltd on behalf of Institution of Chemical Engineers, 2024-11) Beuving M; McNabb WC; Smith NW; Teodosiu C
    Reducing food losses and waste (FLW) can contribute to improving nutrient availability to meet the nutritional needs of the global population. Identifying foods that contribute most to nutrient content in FLW is crucial for developing effective strategies to reduce FLW. Here, we assessed the current literature for quality and consistency of FLW data, and then evaluated the quantity of nutrients that are wasted as a consequence of FLW, identifying the primary food sources contributing to this on a global scale. Several FLW definitions and quantification methods were identified in the literature, making it difficult to compare FLW data and estimates of nutrient content in FLW between existing studies. The nutrient content in global FLW was determined for 29 nutrients from 99 food commodities with the DELTA Model®, after which the contribution of each food group to the nutrient content of FLW was calculated. An indicator was developed to assess the potential impact of resolving FLW on global nutrient availability. Nutrient content in FLW was highest for phosphorus (69 % of global requirement), tryptophan (62 %), thiamine (61 %), methionine (58 %) and histidine (54 %). For 17 out of 29 nutrients, >40 % of the global requirement was embedded in FLW. Cereals contributed most to nutrient losses, followed by fruits and vegetables. According to the indicator, rice, wheat, vegetables, maize, and milk provided the greatest opportunity for increasing nutrient supply via reduction of FLW, due to the combination of waste rates and nutrient density. Our findings highlight the importance of broadening FLW research beyond food mass to incorporate nutritional aspects as important indicators, and to identify key food items to reduce FLW for the improvement of nutrient availability.
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    Alternative protein-based foods must contribute to micronutrient adequacy
    (Taylor and Francis Group on behalf of the Royal Society of New Zealand, 2024-01-29) Smith NW; Fletcher AJ; McNabb WC
    Sustainable diets must consider health, economic, environmental, and social outcomes. The development and production of alternative protein foods should also make these considerations. We examined the nutritional role of these foods, with New Zealand (NZ) as a case study. We used the DELTA Model® to assess 2020 NZ nutrient supply. We then simulated the substitution of 50% of meat supply (by mass) with various plant protein sources (soy, peas, beans, and mushroom), and observed the impact on nutrient supply. NZ had an undersupply of calcium (38%), vitamin E (34% deficit), dietary fibre (20%), potassium (13%), and vitamin C (10%) compared to population requirements. Contrastingly, there was sufficient protein and amino acid supply for an additional 2.4 million people. Halving of meat supply resulted in decreased availability for potassium (21% deficit), zinc (17%), folate (10%), and iron (9%). Soy proved the best nutritional replacement for meat, with reduced deficits for all undersupplied nutrients compared to 2020. Replacement with other modelled protein sources resulted in greater nutrient deficits. The nutritional implications beyond protein must be considered when making dietary substitutions. There are clear public health reasons to fortify alternative proteins with both the nutrients lost in substitution and those already in deficit.
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    Mathematical modelling supports the existence of a threshold hydrogen concentration and media-dependent yields in the growth of a reductive acetogen.
    (Springer Nature Limited, 2020-05-01) Smith NW; Shorten PR; Altermann E; Roy NC; McNabb WC
    The bacterial production of acetate via reductive acetogenesis along the Wood-Ljungdahl metabolic pathway is an important source of this molecule in several environments, ranging from industrial bioreactors to the human gastrointestinal tract. Here, we contributed to the study of reductive acetogens by considering mathematical modelling techniques for the prediction of bacterial growth and acetate production. We found that the incorporation of a hydrogen uptake concentration threshold into the models improves their predictions and we calculated this threshold as 86.2 mM (95% confidence interval 6.1-132.6 mM). Monod kinetics and first-order kinetics models, with the inclusion of two candidate threshold terms or reversible Michaelis-Menten kinetics, were compared to experimental data and the optimal formulation for predicting both growth and metabolism was found. The models were then used to compare the efficacy of two growth media for acetogens. We found that the recently described general acetogen medium was superior to the DSMZ medium in terms of unbiased estimation of acetogen growth and investigated the contribution of yeast extract concentration to acetate production and bacterial growth in culture. The models and their predictions will be useful to those studying both industrially and environmentally relevant reductive acetogenesis and allow for straightforward adaptation to similar cases with different organisms.