Calcium, Iron, and Zinc Bioaccessibilities of Australian Sweet Lupin (Lupinus angustifolius L.) Cultivars

Physicochemical Properties and Metal Ion-Binding Capacity of Thermal-Induced Antarctic Krill Protein Aggregates under Different pH Conditions

Protein properties can be modified by thermal treatment at different pH values, resulting in the formation of protein aggregates with diverse morphologies and functionalities. This study investigated the morphology of aggregates of Antarctic krill protein (AKPS) formed by thermal treatment (90 °C, 15 min) at pH 2, 3, 4, and 6-12, characterized the different morphologies of AKPS, and determined the metal ion (Ca2+, Fe2+, and Zn2+)-binding capacities. Results showed that heat treatment with different pH values generated various AKPS with distinct morphology and metal ion-binding abilities. AKPS have formed fibrils at pH ≤ 3, particles at pH 4-7, and amorphous aggregates at pH ≥ 8. Fibrous AKPS (pH 2) exhibited a high solubility (80.36%) and strong reducing effect on iron. The binding capacities of Ca2+ and Fe2+ reached 36.08% and 66.75%. Particulate AKPS (pH 6 and 7) primarily only showed Zn2+-binding capacity similar to that of casein phosphopeptide (17.33%). Amorphous AKPS (pH 9-11) displayed the optimal capacity to bind Zn2+ and Fe2+ (26.90% and 74.94%). The alterations in morphology and functional characteristics of AKPS permit the design of various nanostructures for food-derived mineral supplements, thus developing their potential for application in functional foods.

Compositional Attributes of Blue Lupin (Lupinus angustifolius) Seeds for Selection of High-Protein Cultivars

Lupin is a promising protein source with a high protein concentration. Breeding efforts have resulted in the development of varieties low in quinolizidine alkaloids. The objective of this work was to evaluate 22 different blue lupin genotypes for a high protein concentration and low content of antinutritional alkaloids. These genotypes were grown under uniform controlled environmental and soil conditions, and the harvested seeds were evaluated for their composition. The low phosphorus content confirmed that the phytic acid presence was low in lupin, especially compared to other legumes. Furthermore, some of the varieties had less than 200 ppm alkaloids. Lupin proteins were rich in leucine and lysine, with the lowest amino acid concentration being methionine. There were significant differences in the protein concentration and recovery. This work demonstrated that an approach for selection of genotypes should be based on not only agronomic yields but also nutritional phenotypes, driving better decision making on future varietal selection.

Multielemental, Nutritional, and Proteomic Characterization of Different Lupinus spp. Genotypes: A Source of Nutrients for Dietary Use

Among grain pulses, lupins have recently gained considerable interest for a number of attractive nutritional attributes relating to their high protein and dietary fiber and negligible starch contents. The seeds of Lupinus albus (cv. Multitalia and Luxor, and the Modica ecotype); L. luteus (cv. Dukat, Mister, and Taper); and L. angustifolius (cv. Sonet) analyzed in this study were deposited within the germplasm collection of the Research Centre for Cereal and Industrial Crops of Acireale and were sowed in East Sicily in 2013/14. The collected seeds were analyzed for their multielemental micro- and macronutrient profiles, resulting in a wide variability between genotypes. Lupin seed flour samples were subjected to a defatting process using supercritical CO₂, with oil yields dependent on the species and genotype. We determined the fatty acid profile and tocopherol content of the lupin oil samples, finding that the total saturated fatty acid quantities of different samples were very close, and the total tocopherol content was about 1500.00 µg/g FW. The proteomic analysis of the defatted lupin seed flours showed substantial equivalence between the cultivars of the same species of Lupinus albus and L. luteus. Moreover, the L. angustifolius proteome map showed the presence of additional spots in comparison to L. albus, corresponding to α-conglutins. Lupin, in addition to being a good source of mineral elements, also contributes vitamin E and, thanks to the very high content of gamma-tocopherols, demonstrates powerful antioxidant activity.

Temporal Change in Iron Content of Vegetables and Legumes in Australia: A Scoping Review

Studies in UK and US have reported a temporal decline in the iron content of plant-based foods. Limited research on this topic has been conducted in Australia. The aim of this scoping review was to provide a comprehensive evaluation on the temporal change in iron content of Australian vegetables and legumes from 1900 onward. A systematic search of electronic databases, websites, backward reference searching, and Australian food composition tables was conducted. A total of 34 articles and six versions of Australian food composition databases published between 1930s to 2021, were included in this review. Overall, iron content of vegetables and legumes were assessed at limited time points and geographical origin, cultivars, sampling and analytical techniques varied across studies. The majority of vegetables had similar iron content between two or more timepoints but decreases of 30-50% were noted for sweet corn, red-skinned potatoes, cauliflower and green beans while increases of 150-300% were seen for Hass avocadoes, mushrooms and silverbeet. More pronounced reductions in iron content were observed for legumes, with higher and more variable values reported pre-2000 compared to recent years. Due to limited data and variations in sampling and analytical techniques, no definitive conclusions could be established. As plant-based diets are becoming more popular, consistent monitoring of the nutrient composition of staple plant-based foods is strongly recommended.

Bioaccessibility of Some Essential Minerals in Three Selected Australian Pulse Varieties Using an In Vitro Gastrointestinal Digestion Model

Australian produced pulse grains are exported worldwide, predominantly to developing countries where severe essential mineral deficiencies putatively subsist. An in vitro digestion model that simulates human gastric, intestinal and colonic digestion and fermentation, was used to examine the bioaccessibility of Fe, Mg, K, Ca, P, Zn, Mn, and Cu in commercially available cultivars of Australian field pea, lentil, and sweet lupin. The hull and dehulled seeds were prepared following a traditional cooking method, and quantities of bioaccessible minerals were assessed at each stage of in vitro digestion using ICP-OES elemental analyses. Results revealed that dehulled field pea (100 g dry weight) had the highest bioaccessible quantity of Fe (2.44 ± 0.73 mg), K (717.10 ± 56.66 mg), P (272.88 ± 9.30 mg), Zn (1.72.028 ± 0.28 mg), and Cu (0.41 ± 0.02 mg). Dehulled lupin was the best source of Mg (138.62 ± 1.53 mg) and Mn (1.28 ± 0.0.06 mg), and lentil hull showed the greatest Ca bioaccessible quantity (116.33 ± 16.73 mg/100 g dry weight). Additionally, the fed state digestion (11.7 mg bile/mL sample) increased the bioaccessibility of all elements significantly (P < 0.05) compared to fasted (1.95 mg bile/mL sample), except for Zn and Mn in lupin and lentils. These results demonstrated that dehulled seeds possess higher mineral bioaccessibility on a percentage basis compared with hulls, and that the fed state of in vitro digestion generally improved the mineral solubility significantly (P < 0.05). PRACTICAL APPLICATION: This research aimed to assess the prospective biological accessibility of various essential elements in three commercially available Australian pulses. Results of the study provided an insight into the contents of essential minerals in Australian pulses and illustrated the impact of traditional cooking of dehulled pulses on these minerals bioaccessibility. These findings will provide the consumers with information about some nutritional aspects of major Australian pulses.