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Maize porridge, known as ''polenta'' in Italy, is a global staple food. This study aims to characterize the quality of four Italian flint maize landraces by investigating physical properties and macronutrients composition. By using SPME GC–MS and PTR-ToF-MS we analyzed the flours volatilome and changes in aroma profile post- cooking. Cooking induced the formation of 5 compounds and the loss of up to 25 compounds, primarily through evaporation. Post-cooking, the concentrations of some sulphur compounds (methanethiol, dimethyl sulfide and dimethyl trisulfide), lipid oxidation compounds (2-pentylfuran and hexanal) and Maillard reaction compounds including some aldehydes (nonanal, benzaldehyde, phenylacetaldheyde), pyridine and furans (furfural and furfuryl alcohol) increased. Differences in volatilome and macronutrients contents among landraces were also observed with Marano samples having on average a significantly higher concentration of proteins (13.67 %), while the Nostrano samples had the highest fat content (5.00 %). Fatty acid profile differences were mirrored in the volatilome. Spin flours had the highest level of linoleic acid, leading to elevated levels in cooked polenta due to linoleic acid oxidation. The differences in volatilome and macronutrients contents among the samples confirmed that local landraces are not only important for biodiversity and cultural heritage but also lead to unique aroma compounds profiles.

BACKGROUND: Protein percentage and kernel weight affect the endosperm hardness of maize grains. However, changes in starch composition could also modify kernel hardness, which is often predicted through milling ratio. The objective of this work was to evaluate the relationship between changes in starch composition and endosperm hardness, and to assess the effects of protein content and kernel weight on that relationship. For this, we used information obtained from three temperate hybrids in multi‐environmental experiments, as well as experiments conducted under controlled conditions designed to modify starch composition. Milling ratio was determined as maize kernel hardness predictor in both experiments and it was correlated with grain weight and grain composition. RESULTS: In both experiments, milling ratio presented a significant Spearman correlation coefficient with amylose/starch ratio. Milling ratio was significantly related to the amylose/starch ratio using a simple fit with datasets from different experiments and hybrids. Increases in amylose/starch ratio were associated with increases in milling ratio. CONCLUSION: Starch composition was related to milling ratio variations among hybrids of different aptitude for dry milling through different environments, regardless of protein content. Thus, increases in the amylose/starch ratio were related to increases in the milling ratio. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Mechanical threshing used when preparing maize seeds for planting subjects seed to damage and reduces seed quality. The purpose of this study was to assess the effect of mechanical threshing on the quality of maize seed threshed at different moisture contents (MCs). Seeds of dent maize JK968 and flint maize DD2 were threshed at 12, 15, 18, 21, and 24% MC. The damage degree was determined by iodine staining, and seed vigor was assessed by standard germination (SG), cold test germination (CTG), accelerated aging germination (AAG), seedling emergence rate, and seedling root and shoot length. The results showed that the damage percentage increased, and the seed vigor parameters decreased with increasing seed MC during threshing in both cultivars. For obtaining high seed quality, indicated by at least 90, 85, and 80% of SG, AAG, and CTG, respectively, JK 968 and DD2 should be threshed at MC lower than 15 and 18%, respectively. Furthermore, the damage mainly occurred in the apical part of seeds, irrespective of the threshing MC in both cultivars. When the embryo was damaged, seedling emergence rates were significantly reduced with great influence on shoot length. Damage to the endosperm resulted in little effect on seedling performance. Flint maize DD2 was more tolerant to mechanical threshing than dent maize JK968. These results provided technical reference for the production and processing of high vigor maize seeds.

Distribution of phenolics in Indian dent and flint yellow maize was analyzed. HPLC and ESI-MS/MS results indicated that germ of maize samples contained significantly higher free phenolic acids than pericarp whereas, pericarp contained more bound phenolics. Free and bound phenolic acids in pericarp, germ and endosperm of dent maize were 267.5 ± 28.9 and 4329.6 ± 221.5; 468.7 ± 23.0 and 3428.6 ± 101.2; 6.2 ± 0.6 and 172.0 ± 11.1 µg/g, respectively, whereas in flint corn these values were 157.9 ± 27.4 and 5523.3 ± 292.2; 262.3 ± 20.8 and 1341.9 ± 80.6; 19.3 ± 1.3 and 224.0 ± 14.6 µg/g, respectively. Vanillic, syringic, p-hydroxybenzoic, protocatechuric, caffeic, p-coumaric and ferulic acids were detected among phenolic acids. Among flavonoids, cyanidin-3-O-glucoside, kaempferol and quercetin were also detected in trace amounts in the yellow maize. The pattern of radical scavenging by bound phenolic extract of pericarps varied between the samples. Peroxide scavenging and reducing capacity of botanical fractions also varied similarly. Free phenolics contributed 0.6–1.7, 5–15 and 46–60% to the anti-radical, peroxide scavenging and reducing capacity, respectively. Among lipophilic tocochromanols, γ-tocopherol was the most abundant homolog and varied significantly in its content for dent (29.4 ± 8.7 µg/g) and flint maize (63.2 ± 7.5 µg/g). Data show that dent and flint maize hold promise for the development of whole grain functional foods.

Several preclinical studies have suggested that the regular consumption of flavonoid-rich foods is associated to a reduced risk of chronic diseases. For this reason, in the last years a renewed interest for the ancient landraces rich in flavonoids or other bioactive molecules is growing. Preservation and valorisation of these ancient landraces is very important, not only for economic considerations regarding the farmers within the small rural communities, where the particular maize germplasm has been developed, but also from a scientific point of view. In this work we characterized the ancient cultivar named 'Nero Spinoso' from the Camonica valley, the biggest valley in the north-west region of Lombardy (Italy). The peculiarity of this landrace is the colour and the pointed shape of the kernels. We showed after spectrophotometric and TLC analysis that this variety accumulates high amounts of phlobaphenes (320 A/100 g flour). Genetic data demonstrate that phlobaphene pigmentation is under the control of a monogenic dominant gene. Further mapping and sequencing data showed that the pigmentation is driven by the presence of a strong allele of Pericarp 1 ( P1) gene, a transcription factor belonging to the myb transcription factor gene family. The 'Nero Spinoso' variety represents an ancient landrace that could be considered a real functional food and a useful tool in future breeding programmes. [ABSTRACT FROM AUTHOR]

Distribution of phenolics in Indian dent and flint yellow maize was analyzed. HPLC and ESI-MS/MS results indicated that germ of maize samples contained significantly higher free phenolic acids than pericarp whereas, pericarp contained more bound phenolics. Free and bound phenolic acids in pericarp, germ and endosperm of dent maize were 267.5 ± 28.9 and 4329.6 ± 221.5; 468.7 ± 23.0 and 3428.6 ± 101.2; 6.2 ± 0.6 and 172.0 ± 11.1 µg/g, respectively, whereas in flint corn these values were 157.9 ± 27.4 and 5523.3 ± 292.2; 262.3 ± 20.8 and 1341.9 ± 80.6; 19.3 ± 1.3 and 224.0 ± 14.6 µg/g, respectively. Vanillic, syringic, p- hydroxybenzoic, protocatechuric, caffeic, p- coumaric and ferulic acids were detected among phenolic acids. Among flavonoids, cyanidin-3-O-glucoside, kaempferol and quercetin were also detected in trace amounts in the yellow maize. The pattern of radical scavenging by bound phenolic extract of pericarps varied between the samples. Peroxide scavenging and reducing capacity of botanical fractions also varied similarly. Free phenolics contributed 0.6–1.7, 5–15 and 46–60% to the anti-radical, peroxide scavenging and reducing capacity, respectively. Among lipophilic tocochromanols, γ-tocopherol was the most abundant homolog and varied significantly in its content for dent (29.4 ± 8.7 µg/g) and flint maize (63.2 ± 7.5 µg/g). Data show that dent and flint maize hold promise for the development of whole grain functional foods. [ABSTRACT FROM AUTHOR]

Food grade maize dedicated to dry milling is an ingredient used in everyday foods, such as breakfast cereals, snacks, baked goods, and beer. Argentina has developed a supply chain producing high quality food grade hard endosperm maize for national and international dry milling markets. In modern times, European countries uniquely source their imported hard endosperm food grade maize from Argentina. Here we describe some of the challenges and opportunities this centralized supply chain is facing. There is a 10–30% yield gap between regular dent and hard endosperm commercial hybrids, depending on the specific genotype and environment, and we anticipate it will continue increasing. Grain quality vs. yield trade-off is the most important challenge, and to cope with this issue the supply chain is slowly adapting to use food grade hybrids with higher physical field yields but slightly lower grain hardness than traditional ones. However, there is a clear opportunity to genetically manipulate grain hardness thanks to the known role of the specific proteins involved. Another opportunity is crop management optimization at the field level. Minimum advice is given to farmers other than genotype selection, leaving them with limited decision support regarding fertilizer or plant population, two management practices with significant grain quality effects. Opportunities also arise from market development based on the nutritional characteristics of this specialty grain (such as 122% higher β-branch carotenoids, 4% lower glycemic index of cooked flours because of lower starch digestibility, and 37% higher grain Zn than softer dent germplasm), or sustainability aspects of the supply chain. We highlight the capacity to track farmers through the current use of identity preserved (IP) programs detailing where, who, and how the grain was produced or impose any needed farming practice change. All these aspects are relevant for other food chains using maize dry milling products around the globe. • Largest challenge related to yield vs. quality trade-off. • Tailored field management recommendations for food grade maize are needed. • New specific protein knowledge provides the opportunity for genetic manipulations. • Market opportunities exist based on the nutritional characteristics of this specialty grain. • Current IP programs are a strength for sustainable sourcing needs from food companies. [ABSTRACT FROM AUTHOR]

Abstract: Dry-milling performance of maize (Zea mays, L.) kernels primarily depends on their hardness. The flint type is harder than the dent and semi-dent maize, yielding a higher proportion of big endosperm pieces in the mill. Nevertheless, crop growing conditions could modify milling properties. The objective of this work was to analyze the effect of different crop environments and management practices on dry-milling quality of flint maize kernels. Two orange-flint hybrids from different eras of breeding differing in flint type expression and grain yield potential were evaluated. They were grown at three different locations of the Argentina''s main maize-production area under different sowing dates, plant densities, and fertilization rates during two growing seasons. Crop post-silking growth, grain yield and its components (kernel number and weight), kernel size and hardness-associated properties (test weight, percent floaters and milling ratio), and flaking-grit yield were analyzed. Most of observed differences in physical properties of kernels, particularly for the high-yielding new hybrid with unstable flint expression, were associated with the source–sink ratio established during the post-silking period (explored range from 154 to 617mgkernel−1). This variable mainly results from changes in crop growth during that period. Increases in weight per kernel improved hardness-associated properties. High crop grain yields together with top dry-milling quality were achieved when the new high-yielding hybrid was cropped with an appropriated crop management. [Copyright &y& Elsevier]

Abstract: Today''s modern Dent×Flint maize (Zea mays L. ssp. mays) hybrids have a high yield potential but often lack satisfying early vigour under typical low spring temperatures of temperate latitudes. Maize was introduced into Europe already in the 16th century and until the 1950s, landraces evolved and adapted well to various geographically restricted and climatically marginal regions in Europe. Therefore, the objective of this study was to assess representatives of the large pool of Swiss Flint maize landraces for their early vigour under cool conditions in the field. A set of 17 landrace accessions were tested for 2 years at sites on the Swiss plateau (450 and 550m a.s.l.) and in the foothills of the Swiss Alps (830 and 870m a.s.l.). Plant emergence (PE), emergence index (EI), the efficiency of the photosystem II (F v/F m), leaf greenness (SPAD) and plant dry weight at the three- and six-leaf stages (DW3P, DW6P) were measured. Compared to a modern European Dent×Flint reference hybrid of good early vigour (Magister), superior early growth was found for several accessions that originated in northern alpine valleys. Three of these landraces (176RV, 151RV and 055LV) combined their good early growth with good early establishment (PE) and seemed to break the usually observed negative association between PE and DW3P or DW6P, a prerequisite for high-yielding plant stands. Plant emergence and establishment were often markedly better for landrace accessions from the Southern Alps, mainly from Tessin region, but their growth performance was significantly lower at the three- and the six-leaf stages. We conclude that northern Swiss landrace accessions in particular show good potential for improving early vigour of maize in cool field environments and we propose that the fast, non-destructive early vigour scoring is an efficient tool for assessing differences in growth in the field during these early plant stages. [Copyright &y& Elsevier]

• Early farming sites exhibit cultural ties to the Tucson Basin Early Agricultural Period. • Maize farming north of the Tucson Basin precedes the appearance of BM II sites. • The Four Corners Basketmaker II complex did not develop in situ. • Low yield, flint maize constrained population growth during the BM II period. • Risk mediated settlement patterns characterize pre-Puebloan farming strategies. The origins of maize farming strategies broadly labeled Basketmaker II have long intrigued archaeologists. Early twentieth century researchers excavating sheltered sites in the Four Corners region of the American Southwest found material culture associated with aceramic farmers that included sophisticated textiles as well as elaborate and exotic mortuary offerings in a region sparsely occupied by foragers. Although early researchers speculated that the San Pedro phase of what is now known as the Early Agricultural Period played a significant role in the emergence of Basketmaker II, data bearing on the topic were scarce for decades. Recent, well-documented excavations in the southern Tucson Basin in advance of urban development have strengthened the argument that pulses of influence, likely including population movement, occurred during this period. Here, we explore the relationship between the Late Archaic, Early Agricultural Period and Basketmaker II maize-dependent economies in search of Basketmaker origins. A complex and dynamic picture emerges calling into question both migration and diffusion arguments for the appearance of Four Corners Basketmaker II. [ABSTRACT FROM AUTHOR]