The Impact of Cooking of Beef on the Supply of Heme and Non-Heme Iron for Humans

Red meat contains a high proportion of heme iron (HI) which is absorbed at a far higher extent into the blood than the non-heme iron (NHI) found in plants. However, HI and NHI are expelled in the juice during cooking while a fraction of HI is converted into NHI, thus decreasing iron bioavailability. This paper relies on experiments and the use of modeling. The kinetics of the conversion of HI into NHI was measured and modeled in juice extracted from uncooked beef meat, and beef cubes were cooked to measure the variations of HI/NHI contents. In meat, HI/NHI ratio decreased from 2.0 when it was raw to less than 1.0 for the longest heat treatments and highest temperatures. The model was used to predict the effect of cooking conditions on the variations of the iron supplied by beef meat. The lowest contribution of meat to iron supply was found for under-pressure cooking at temperatures above 100°C.

Dietary Plant Extracts Combined with Vitamin E Limit the Discoloration in Stored n-3 PUFA Rich Meat

In finishing cull-cows given n-3 PUFA-rich diets (for 101 ± 3 days preceding slaughter), the ability of vitamin E (2.8 g/animal/day) or vitamin E associated with plant extracts rich in polyphenols (PERP) (126 g/animal/day) to limit discoloration was evaluated on color attributes of Longissimus thoracis (LT) and Semitendinosus (ST) processed meat. Color attributes were determined after muscles ageing and retail display in different packaging systems consisting in 14 d. under vacuum (V), 4 d. aerobic (A) or 7 d. under modified atmosphere (70:30, O2/CO2) (MA). Vit. E associated with PERP were able to limit color deterioration by decreasing metmyoglobin% in ST and LT for all tested packaging systems. The antioxidant association increased the L* coordinate and the oxygenation index as compared with vit. E alone. We show the possibility to limit color deterioration of processed beef by an original dietary antioxidant strategy during the finishing period.

尼日利亚肉用鸡的刀豆饲料在微生物发酵前分两阶段水煮对其营养价值的影响

尽管刀豆(Canavalia ensiformis)富含蛋白质(占干重的26%～31%)并含有氨基酸,但在热带地区很少用作家畜的蛋白添加饲料。正如其它热带豆科植物一样,刀豆也含有毒性物质,因此限制了其作为单胃动物的喂养配料。这些有毒物质包括伴刀豆球蛋白A(Con A)(一种植物凝血素)和刀豆氨酸(一种与精氨酸结构相类似的耐热有毒碱性氨基酸)。其它有毒物质还包括副刀豆氨酸和刀豆毒素。以往通过热处理使有毒物质失去活性,结果较好地改善了刀豆的营养价值,使各种家禽饲料中刀豆含量达10%。

杏壳生物炭对温室次生盐渍化土壤修复效应的研究

日光温室土壤次生盐渍化是设施蔬菜生产中的主要障碍性因子。研究以温室盐渍土、杏壳生物炭和负载微生物的杏壳生物炭为主要对象,通过监测土壤培养过程中土壤溶液pH,电导率(EC),水溶性磷、水溶性钾的动态变化,以及相应处理下盐分敏感蔬菜-辣椒的发芽率,探索添加不同比例的生物炭材料对温室次生盐渍化土壤的修复效果。结果表明,经过40 d土壤培养,添加杏壳生物炭对土壤溶液pH影响不明显,但是2.5%低添加量生物炭降低土壤溶液EC值的效果最为明显,在土壤培养的整个时期,添加杏壳生物炭和负载微生物的杏壳生物炭土壤溶液EC值均显著低于CK,且微生物负载生物炭降低土壤溶液EC值的效果更好;此外,添加生物炭不仅降低了土壤水溶性磷钾的变化幅度,有利于磷钾在土壤中的固持,而且显著提高了土壤碳氮比(P <0.05);辣椒发芽率随生物炭材料添加量的增加显著提高(P <0.05),其中添加10%负载微生物的杏壳生物炭辣椒的发芽率可达90%以上,比对照提高2.3倍。综上所述,添加负载微生物的生物炭对设施菜田次生盐渍化土壤的修复效果较好。