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为获得高纯度的澳洲坚果蛋白粉，以低纯度澳洲坚果蛋白粉为原料,采用单因素试验和正交试验确定糖化酶纯化澳洲坚果蛋白粉的最佳工艺条件，在最佳工艺条件下进行中试生产实践（澳州坚果仁—压榨制油—粉碎—脱脂饼粉—加水磨浆—碱溶酸沉—酶解纯化—喷雾干燥—纯化蛋白粉），对纯化后蛋白粉的溶解度、乳化性、持水性和吸油性进行测定，并比较了纯化前后蛋白粉的氨基酸组成及含量。结果表明：澳洲坚果蛋白粉最佳纯化工艺条件为加酶量100 U/g、酶解温度55 ℃、酶解时间90 min、料液比1∶ 8，在此条件下进行中试生产实践，制备的蛋白粉蛋白质含量为76.87%，蛋白得率为32.56%，蛋白质提取率为94.81%；纯化蛋白粉在pH 5.0时溶解度最小、乳化性最低，持水性和吸油性在60 ℃时达到最大；纯化后蛋白粉的氨基酸组成丰富，富含7种必需氨基酸，氨基酸总量为6517 g/100 g，高于纯化前的。综上，澳洲坚果纯化蛋白粉具有良好的品质和功能特性。In order to obtain macadamia nut protein powder with high purity, single factor and orthogonal experiments were used to determine the optimal conditions for purification of macadamia nut protein powder by glucoamylase with low purity macadamia nut protein powder as material. Pilot production(macadamia nut kernel—pressing—crushing—defatted macadamia nut cake powder—adding water and grinding—alkaline solution and acid precipitation—enzymatic hydrolysis purification—spray drying—purified protein powder) was practiced under the optimal process conditions. The solubility, emulsification, water-holding and oil-absorption capacities of the purified protein powder were determined, and the amino acid composition and content of the protein powder before and after purification were compared. The results showed that the optimal purification conditions for macadamia nut protein were as follows: enzyme dosage 100 U/g, enzyme hydrolysis temperature 55 ℃, enzyme hydrolysis time 90 min, and material-liquid ratio 1∶ 8. Under the optimal conditions, the pilot production showed that the protein content of the purified protein powder was 76.87%, the protein yield was 32.56%, and the protein extraction rate was 94.81%. The solubility of the purified protein powder was the smallest at pH 5.0, and the emulsification was the lowest, the water-holding and oil-absorption capacities reached the maximum value at 60 ℃. The amino acid composition of the purified protein powder was rich in 7 essential amino acids, and the total amino acid amount was 65.17 g/100 g, which was higher than that of the pre-purification. In conclusion, the purified protein powder of macadamia nut has good quality and functional properties.

Macadamia nut polypeptides were prepared by enzymatic hydrolysis of macadamia nut meal, and suitable proteases for the preparation of macadamia antioxidant polypeptides were screened with ABTS+ radical scavenging effects as evaluation indicators. Four constituents (MNAP-1, MNAP-2, MNAP-3, MNAP-4) were obtained by DA201-C macroporous resin and dialysis technology. The scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·), hydroxyl radical and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonate radicals) radical (ABTS+·), and reducing power were investigated by comparing with glutathione as controls. The results showed that the suitable protease was complex protease for the preparation of macadamia antioxidant polypeptides, which was better than neutral protease, acid protease, alkaline protease, papain and bromelain at the same concentration. Antioxidant activities of different molecular weight macadamia nut polypeptides were different, which all had strong scavenging capacity against DPPH and ABTS+ radicals, and also had certain scavenging capacity against hydroxyl radical and reducing power. MNAP-4 (molecular weight less than 1000 Da) had the strongest scavenging capacity against DPPH, ABTS+ and hydroxyl radicals and the highest reducing power with half maximal inhibitory concentration (IC50) of 0.36, 6.75, 0.08 and 3.19 mg/mL, respectively, which was lower than other molecular weight polypeptides. Correlation analysis showed different molecular weight macadamia nut polypeptides had good correlations with their DPPH, hydroxyl and ABTS+ radicals scavenging capacity and reducing power with r values of 0.947, 0.964, 0.948 and 0.856 (P

Macadamia nuts are one of the most important economic food items in the world. Pericarp thickness and flavonoid composition are the key quality traits of Macadamia nuts, but the underlying mechanism of pericarp formation is still unknown. In this study, three varieties with significantly different pericarp thicknesses, namely, A38, Guire No.1, and HAES 900, at the same stage of maturity, were used for transcriptome analysis, and the results showed that there were significant differences in their gene expression profile. A total of 3837 new genes were discovered, of which 1532 were functionally annotated. The GO, COG, and KEGG analysis showed that the main categories in which there were significant differences were flavonoid biosynthesis, phenylpropanoid biosynthesis, and the cutin, suberine, and wax biosynthesis pathways. Furthermore, 63 MiMYB transcription factors were identified, and 56 R2R3-MYB transcription factors were clustered into different subgroups compared with those in Arabidopsis R2R3-MYB. Among them, the S4, S6, and S7 subgroups were involved in flavonoid biosynthesis and pericarp formation. A total of 14 MiMYBs’ gene expression were verified by RT-qPCR analysis. These results provide fundamental knowledge of the pericarp formation regulatory mechanism in macadamia nuts.

The consumption of macadamia nuts has increased due to their cardioprotective and antioxidant properties. However, this rise is consistent with an increase in the cases of macadamia nut allergy, leading to severe reactions. Although two Macadamia integrifolia allergens (Mac i 1 and Mac i 2) have been identified in Australian and Japanese patients, the allergenic sensitization patterns in Western European populations, particularly in Spain, remain unclear. For this purpose, seven patients with macadamia nut allergy were recruited in Spain. Macadamia nut protein extracts were prepared and, together with hazelnut and walnut extracts, were used in Western blot and inhibition assays. IgE-reactive proteins were identified using MALDI-TOF/TOF mass spectrometry (MS). Immunoblotting assays revealed various IgE-binding proteins in macadamia nut extracts. Mass spectrometry identified three new allergens: an oleosin, a pectin acetylesterase, and an aspartyl protease. Cross-reactivity studies showed that hazelnut extract but not walnut extract inhibited macadamia nut oleosin-specific IgE binding. This suggests that oleosin could be used as marker for macadamia–hazelnut cross-reactivity. The results show an allergenic profile in the Spanish cohort different from that previously detected in Australian and Japanese populations. The distinct sensitization profiles observed highlight the potential influence of dietary habits and environmental factors exposure on allergenicity.

The aim of the study was to explore the impact of both the macronutrient composition and snacking timing on the postprandial glycemic insulinemic responses and food intake. Seventeen healthy female volunteers completed the randomized crossover trials. The volunteers were provided a standard breakfast and lunch at 8:00 and 13:00, respectively, and an ad libitum dinner at 18:00. Provided at either 10:30 (midmorning) or 12:30 (preload), the glycemic effects of the three types of 70 kcal snacks, including chicken breast (mid-C and pre-C), apple (mid-A and pre-A), and macadamia nut (mid-M and pre-M), were compared with the non-snack control (CON), evaluated by continuous glucose monitoring (CGM). The mid-M showed increased insulin resistance after lunch compared with CON, while the pre-M did not. The pre-A stabilized the glycemic response in terms of all variability parameters after lunch, while the mid-A had no significant effect on postprandial glucose control. Both the mid-C and pre-C improved the total area under the glucose curve, all glycemic variability parameters, and the insulin resistance within 2 h after lunch compared with CON. The pre-C attained the lowest energy intake at dinner, while the mid-A and the mid-M resulted in the highest. In conclusion, the chicken breast snack effectively stabilized postprandial glycemic excursion and reduced insulin resistance while the macadamia snack did not, regardless of ingestion time. Only as a preload could the apple snack mitigate the glucose response after the subsequent meal.

O conhecimento dos estádios florais e do desenvolvimento das nozes da nogueira-macadâmia é indispensável para o adequado manejo das plantas, visando a pesquisas de polinização e de cruzamentos controlados. Pesquisaram-se, neste trabalho, os padrões fenológicos temporais de sete cultivares de macadâmia (Macadamia integrifolia), do banco de germoplasma do Instituto Agronômico (IAC). Verificaram-se pequenas variações entre os estágios fenológicos iniciais, desde a emissão dos rácemos até a fase de botão floral inchado. O ciclo desde a emissão do botão floral até a queda dos frutos foi de 253 dias. Os estágios fenológicos - frutos maduros e queda dos frutos - ocorreram a partir do dia 10 de fevereiro até o final de março.The knowledge of phenological stages and nut development of macadamia trees is essential for the adequate management of the plant, aiming pollination studies and controlled crossing between cultivars, needed in breeding programs. The phenological temporal patterns of seven macadamia cultivars selected at the Instituto Agronômico (IAC) were researched in the collection of cultivars. Small variations were verified among the initial phenological stages, from emission of the racemes up to the swollen flower bud stage. The complete cycle, from the flower bud emission to the fruit dropping took 253 days. The phenological stages - mature fruits and fruit dropping - occurred from the second tenth of February to the end of March.

As unidades de beneficiamento de macadâmia adotam silos secadores distintos, para cada etapa de secagem, a fim de garantir a manutenção da qualidade do produto pela redução da umidade a níveis desejáveis. Diante da necessidade de quantificar a resistência apresentada pelas nozes, submetidas a diferentes fluxos de ar durante a secagem, bem como avaliar a possibilidade de utilização de modelos empíricos, que estimem o gradiente de pressão a partir da vazão de ar, conduziram-se vários testes em laboratório para obtenção de dados experimentais e ajuste de modelos. Frutos de macadâmia (M. integrifolia), com umidade de 0,11 b.s., após limpeza e classificação, foram colocados no interior de um protótipo constituído por uma coluna de chapa galvanizada (com tomadas para medição da pressão estática), plenum e ventilador, sendo submetidos a diferentes fluxos de ar. Os testes consistiram de três medidas por profundidade, para cada um dos três lotes de nozes, perfazendo um total de nove medidas de pressão estática por profundidade na coluna. Os resultados obtidos permitiram concluir que os fluxos de ar testados apresentaram efeito significativo sobre a queda de pressão estática na coluna de macadâmia, a qual aumentou linearmente com a profundidade. Os dados experimentais ajustaram-se muito bem aos modelos de Shedd e Hunter, sugerindo sua boa aplicabilidade para a macadâmia.The macadamia processing units use different drying silos, for each drying stage, in order to reduce nuts-in-shell moisture content. Due to the need to quantify the resistance presented by the nuts submitted to different drying airflows, as well as, to evaluate the use of empiric models that predicted pressure losses from airflow, it was carried out several tests in laboratory to obtain experimental data and adjustment of models. Macadamia nuts (M. integrifolia) with 0.11 b.s. moisture content after cleaning and classification were placed into an apparatus constituted by a column of galvanized sheet (in different positions for measuring the static pressure), plenum and fan, being submitted to different airflows. The tests consisted of three repetitions (measures), with three lots of nuts, bringing up to nine measures of static pressure for each position in the column. The obtained results allowed to conclude that the tested airflows showed significant effect on the static air pressure in the macadamia column, which increased lineally with the depth. The experimental data adjusted very well to the Shedd and Hunter's models, suggesting their good suitability for macadamia.

Foi estudada a oxidação de lipídeos adicionados a farinhas de castanha do Pará (Bertholleta excelsa), de macadâmia (Macadâmia integrifolia) e de soja (Glycine max) equilibradas nas atividades de água (Aa) 0,51; 0,57; 0,67; 0,75; 0,79 e 0,81, a 35°C. O substrato utilizado para quantificar tanto a oxidação autocatalítica como a oxidação enzímica foi o óleo de soja na proporção de 20% (p:p). Dois mecanismos de oxidação de lipídeos concorrem pelo substrato nas condições estudadas. A baixos valores de Aa - de 0,51 a 0,75 - o mecanismo mais eficiente é a autoxidação devida à maior exposição do substrato ao oxigênio e à menor mobilidade dos reagentes - enzima e lipídeo - nas reações de natureza enzímica. Em valores de Aa maiores - 0,79 e 0,81 - predomina a oxidação enzímica, e atua a proteção do substrato pela água, frente à ação do oxigênio. O índice de peróxido medido no transcurso de 6 dias apresenta máximos e mínimos devidos a reações secundárias atuando sobre produtos das reações primárias.Lipid oxidation was studied on the flour of Brazil-nut (Bertolleta excelsa), macadâmia nut (Macadamia integrifoliá) and soybean seed (Glycine max), in enviroments with controlled water activity (Aw) values of 0.51; 0.57; 0.67; 0.75; 0.79 and 0.81 at 35°C. Every 24 hours during 6 days the peroxide value was determined for each Aw in flour with enzyme inactivation (110°C, 2 hours) as well as in flour without inactivation. At low Aw values (up to 0.75) the oxidation by oxigen is the most effective mechanism of deterioration of the lipids. At higher water activity values (0.79 and 0.81) the protective effect of the humidity upon the lipids and the greater mobility of the reagents make the activity of the lipoxigenase the most important mechanism of lipid deterioration.