Youna Hemery

Wheat Aleurone: Separation, Composition, Health Aspects, and Potential Food Use

Over the last three decades substantial attention has been given to the role of dietary fiber in health and disease, in particular diabetes, cardiovascular disease, intestinal health, and some types of cancer. As a result the food industry started to add back fiber to refined foods and develop fiber rich foods. Scientists suggested that whole grain foods are superior to foods enriched with fibers obtained/synthesized using enzyme treatment, and thermal or chemical processing because the content of bioactive components and micronutrients in whole grain is more abundant. This triggered interest in how to isolate the micronutrient rich aleurone fiber fraction from wheat. Aleurone is a single cell layer at the inner site of the bran. It contains most of the minerals, vitamins, phenolic antioxidants, and lignans of the wheat grain. Novel milling and dry-fractionation techniques have recently allowed for full-scale separation of aleurone cells from the other layers of wheat bran, yielding a fiber rich concentrate which potentially contains many of the “whole grain kernel bioactives,” which recently have been used in a variety of studies. The present review highlights available data on aleurone isolation, composition, intestinal physiology, and its metabolism and potential health benefits as well as its use in food.

Lactic acid fermentation as a tool for increasing the folate content of foods.

ABSTRACT Folate is an essential micronutrient involved in numerous vital biological reactions. The dietary consumption of naturally occurring vitamin B9 is often inadequate in many countries, and supplementation or fortification programs (using synthetic folic acid) are implemented to alleviate folate deficiency. Other food-based alternatives are possible, such as the use of lactic acid bacteria (LAB) to synthesize folate during fermentation. Many studies have been conducted on this topic, and promising results were reported for some fermented dairy products. However, in other studies, folate consumption by LAB or rather low folate production were observed, resulting in fermented foods that may not significantly contribute to the recommended B9 intake. In addition, the optimum conditions for folate biosynthesis by LAB are still not clear. The aim of this review was thus to (i) clarify the ability of LAB to produce folate in food products, (ii) check if the production of folate by LAB in various fermented foods is sufficient to meet human vitamin B9 requirements and (iii) suggest ways to optimize folate production by LAB in fermented food products.

Influence of light exposure and oxidative status on the stability of vitamins A and D3 during the storage of fortified soybean oil

Food fortification is implemented to address vitamins A and D deficiencies in numerous countries. The stability of vitamins A and D3 was assessed during a two-month period reproducing the usual oil storage conditions before sale to consumers. Soybean oils with different oxidative status and vitamin E contents were stored in the dark, semi-dark, or exposed to natural light. Lipid peroxidation took place after 3 weeks of storage in dark conditions. After 2 months, the vitamin A and D3 losses reached 60-68% and 61-68%, respectively, for oils exposed to natural light, and 32-39% and 24-44% in semi-dark conditions. The determining factors of vitamin A and D3 losses were (in decreasing order) the storage time, the exposure to light and the oxidative status of the oil, whereas vitamin E content had a protective role. Improving these parameters is thus essential to make vitamins A and D fortification in oils more efficient.

Storage conditions and packaging greatly affects the stability of fortified wheat flour: Influence on vitamin A, iron, zinc, and oxidation

Micronutrient deficiencies result in irreversible physical and cognitive consequences. Fortification of flour is widely applied to address micronutrient deficiencies, but vitamin losses can occur during the storage of fortified products. This work aimed at assessing the combined influence of different factors on vitamin A retention and the oxidative status of wheat flours: storage duration (up to 6months), temperature during storage, relative humidity within storage facilities, type of packaging (oxygen-permeable or not), and premix composition (with or without ferrous sulphate). Vitamin A degradation was high and occurred rapidly: more than 45% was lost within 3months in the mildest conditions, whereas over 85% was lost within 3months in the most severe conditions. Vitamin A retention was related to the extent of oxidation reactions that occurred in flours during storage, and the factors that mostly affected vitamin A retention were the storage duration, the type of packaging and the temperature.

Premises for the Electrostatic Separation of Wheat Bran Tissues

New fractionation technologies are presently under investigation in order to enhance the wheat bran nutrient value. The explicit aim of the present paper was to evaluate the possibility of using the electric field forces for the separation of the fine particles generated from each wheat bran tissue during the milling process. Corona charging and surface potential decay experiments were performed on samples of more or less finely- grinded wheat bran and aleurone tissues. For both kinds of samples, finer particles charged better than larger particles, and lyophilized samples were found to better preserve their charge than those not subjected to a freeze-drying process. An experiment carried out using a belt-type corona-electrostatic separator validated the possibility of sorting these tissues based on the differences in their charge decay charcateristics. Tribocharging experiments performed on the same tissues have also led to encouraging results: the charge/mass ratio of ground bran tissues was twice that of aleurone. These differences in the physical properties of the two types of tissues represent the premises for the development of electrostatic separation technologies as part of more efficient bran cracking strategies.