| This study collected 85 papers on Zn(Zn)fortification in wheat.These papers were published from 1964 to 2020.Then,a META analysis was carried out.At the same time,nine wheat varieties in Huanghuai wheat area of different ages were used as test materials.By foliar spraying Zn fertilizer,Zn fortification was carried out at three different growth stages of wheat such as jointing stage,booting stage and filling stage,to study the effect of Zn fortification on Zn content and quality of wheat varieties of different ages.The harvested wheat grains were milled to analyze the Zn-fortification effect on the Zn content and flour quality during wheat processing.At the same time,the Zn-enriched noodles were studied with the prepared Zn-fortified flour as the test material.Five different cooking methods were used to explore the effect of different cooking methods on Zn content retention and Zn bioavailability in noodles.The main conclusions obtained from this experiment are as follows:(1)Grain Zn content in wheat worldwide is 31.84 mg/kg,which was lower than that suggested by the reference of WHO(40-60 mg/kg).Zn fortification is the primary way to increase the grain Zn content of wheat and could be achieved by Zn fertilizer Grain Zn content in wheat improved from 28.96 to 36.63 mg/kg and that in flour increased from 10.51 to 14.82 mg/kg after Zn fortification.Furthermore,Zn content varied in the different processed components of wheat;that is,Zn content was 12.58 mg/kg in flour and 86.45mg/kg in bran.Zn content was also different in wheat-derived foods,such as 13.65 mg/kg,in baked food,10.65 mg/kg in fried food,and 8.03 mg/kg in cooking food.It can be seen that the appropriate Zn fortification,processing methods and cooking methods of flour products have a significant impact on food Zn content.(2)The breeding year of wheat cultivars was negatively correlated with grain and flour Zn content.With the breeding age of wheat varieties from far to near,tgrain and flour Zn content has a decreasing trend.Among them,Youbaomai had the strongest Zn fortification ability,and the newly bred jimai 70 had the best Zn fortification potential and comprehensive quality traits.(3)Field Zn fortification can significantly increase grain,flour and noodles Zn content.Compared with the non-fortification treatment,Zn fortification at the grain filling stage can make the average Zn content of the tested nine wheat varieties reach 28.13 mg/kg,an increase of 13.03%;the mean average flour Zn content reaches 6.47 mg/kg,an increase of 8.92% and noodles Zn content reached 6.11 mg/kg,an increase of 6.08%.At the same time,wheat grains,flour and noodles phytic acid content and phytate acid:Zn molar ratio after Zn fortification were reduced to a certain extent,which was favorable to the improvement of Zn bioeffectiveness.(4)The cooking method had a significant effect on noodles Zn content in steamed(6.26mg/kg),microwaved(5.72 mg/kg)and deep-fried(5.94 mg/kg)compared to raw noodles(6.30 mg/kg)Zn content is not significantly reduced.However,after boiling(5.59 mg/kg)and frying(5.26 mg/kg),noodles Zn content was significantly reduced..After five cooking methods,the order of Zn content in the strips is: steaming > deep-fried > microwave >boiling > frying,The Zn content loss rates in the five different cooking methods were 0.12%,5.71%,9.64%,12.20% and 19.30% in descending order.(5)The cooking methods had significant effects on the phytic acid content and the phytic acid:zinc molar ratio in the noodles.The phytic acid content in the noodles treated by the five cooking methods was in the order from highest to lowest: boiling > steaming >microwave > deep-fried > frying.The loss rate of phytic acid content was 34.25%,34.83%,37.53%,44.58% and 52.68% in descending order.The molar ratios of phytic acid:zinc in the noodles after the five cooking methods were,in descending order: boiling > microwave >steaming > frying > stir-frying.The loss of phytate:Zn molar ratio in the noodles after the five cooking methods was 27.26%,32.14%,35.12%,40.85% and 44.69% in descending order. |
PDF Full Text Request