Summary.Immediately prior to seed fill, a dermal transfer cell complex, comprised of epidermal and subepidermal celis, differentiates on the abaxial surface of the cotyledons in seed of Viciafaba. Over the period of differentiation of this complex in vivo, the principal sugars of the seed apoplasmic sap change from hexoses, glucose and fructose, to sucrose. Cotyledons were removed from seeds before differentiation of the transfer cell complex and cultured for 6 days on an agar-based medium in the dark with their abaxial surface in contact with a medium containing either 100 mM hexoses (glucose and fructose in equimolar concentrations) or 100 mM sucrose. On both media, cotyledon growth rate was maintained throughout the culture period at, or above, that of in vivo grown cotyledons of equivalent developmental age. When cotyledons were cultured on a medium containing glucose and fructose, epidermal cells of both the ab-and adaxial surfaces developed wall ingrowths on their outer periclinal walls and their cytoplasm became dense, vesicular, and rich in mitochondria. Extensive ingrowth deposition also occurred on walls of the subepidermal cells and several rows of underlying storage cells where they abutted intercellular spaces. This latter ingrowth development was apparent on both cotyledon surfaces, but extended into more of the underlying cell layers on the abaxial surface at the funicular end of the cotyledon. In in vivo grown cotyledons, such ingrowth development is restricted to the subepidermal cells of the abaxial surface. Ingrowth morphology was commensurate with that of transfer cells of in vivo grown cotyledons. In contrast to the observed induction on a medium containing glucose and fructose, cotyledons cultured with sucrose as the sole sugar source exhibited no ingrowth deposition or small wall ingrowths in some abaxial epidermal cells. While the potential sugar signalling mechanism is unknown, this culture system offers an exciting opportunity to explore the molecular biology of transfer cell development. Abbreviations: DAA days after anthesis; GC-MS gas chromatography and mass spectrometry; PAR photosynthetically active radiation; RGR relative growth rate; SCM standard culture medium. Keywords:

The UK government has called for industry reformulation of foods that contribute most to sugar consumption in children’s diets, including yogurts. The aim of this work was to comprehensively survey yogurt products available in UK supermarkets in 2019 to determine whether sugar contents had been reduced since our baseline survey in 2016. Product information was collected for 893 unique yogurt, fromage frais and dairy dessert products, and nutrient contents were analysed in comparison to those previously examined. Examining all products, there was a highly significant (p < 0.0001) reduction in the median total sugar contents in 2019 compared to those in 2016: median (interquartile range): 10.4 g/100 g (6.6, 13.0) versus 11.9 g/100 (8.8, 13.6). However, notable product turnover was evident; while 60% of the 2019 products surveyed could be matched by brand and name to 2016, 40% were new. In scrutinising paired products closely, only 32% (173 of 539) had reduced sugar contents with a smaller mean difference of −0.65 g/100 g (p < 0.0001), suggesting that the overall median had dropped as a result of higher sugar products being discontinued. Categories showing the most improvements were children’s, drinks and fruit yogurts. Although only 15% of the 2019 products contained ≤5 g/100 g sugars, considered a ‘low-sugar’ product for labelling, this was an improvement over the 9% identified in 2016. Our results yield important insights into current market trends and demonstrate that the median sugar content of UK yogurt products has been reduced by 13% in two years. These data independently evidence modest, but encouraging changes in response to public policy initiatives aimed at preventing childhood obesity.

AbstractYogurt is a staple part of children's diets and is perceived as a nutrient dense food for adults and children. However, yogurts are also a significant source of free sugars for children and are a target of the UK government's sugar reduction programme, which has recommended a 20% reduction in the sugar content of yogurt and fromage frais products by 2020. With this in mind, in November 2016, we undertook a comprehensive survey of the nutrient contents of yogurt products in UK supermarkets (Moore et al. 2018). The aim of this work was to reassess the UK supermarkets yogurt products in 2019 and determine whether the sugar contents of yogurt products have been reduced. Product data was collected from the UK's top five online supermarkets in January 2019 using the search terms ‘yogurt’ and ‘yoghurt’. Products were placed systematically into the same 8 categories used in 2016: children's, drinks, dairy alternatives, organic, natural/Greek, fruit, flavoured, desserts. Products lists were collected, refined and compared to the 2016 database. All data was double-checked independently and 5% of all entries were randomly selected and verified. GraphPad Prism V/7.0c was used for statistical analysis. After de-duplication of products found in multiple supermarkets, the 2019 database contained 893 unique products in line with the 898 surveyed in 2016. Of these, 539 (60.4%) yogurts were in common (same brand and name) with the 2016 products and 354 were new, demonstrating dynamic turnover in available yogurt products during the 26 months between surveys. In comparing the total sugar contents of the 539 paired products, notably the median [range] of total sugar contents in 2019 was significantly lower than in 2016 (10.8g/100 g [0.4, 29.5] versus 11.8g/100 g [0.1, 31.8]; P < 0.0001, Wilcoxon matched-pairs signed rank test). Indeed, when all products were compared there was a significant reduction in the median total sugar in 2019 compared to 2016 (10.4g/100 g [0–32.9] versus 11.9g/100 g [0.1–32.6]; P < 0.0001, Mann-Whitney test). Categories showing the most improvements were children's, drinks and fruit yogurts. Fifteen percent of the 2019 products contained less than or equal to 5g/100 g sugars, considered a ‘low sugar’ product, an improvement over the 9% identified in 2016. We conclude the sugar content of UK yogurt products has reduced since the sugar reduction program was put into place in 2016. However, a larger reduction in most categories is needed in order to reach the required 20% reduction by 2020.