Susana M. Nolasco

Microstructure, chemical composition and mucilage exudation of chia (Salvia hispanica L.) nutlets from Argentina

BACKGROUND The micromorphology and anatomy of nutlets, myxocarpy (mucilage exudation) and mucilage structure of Argentinean chia were described using scanning electron microscopy (SEM). The proximal composition of nutlets and mucilage was also studied. RESULTS Chia nutlets are made up of a true seed and a pericarp enclosing the seed; they are small, glabrous, elliptic and apically rounded. The pericarp has cuticle, exocarp, mesocarp and bone cells vertically arranged and endocarp. The myxocarpy was carefully recorded by SEM. After 5 min in contact with water, the cuticle of nutlets is broken and the exocarp cell content gradually surrounds the rest of the nutlet. The proximal composition of chia nutlets was studied; fat is the major component (327 ± 8.0 g kg(-1)) followed by protein (293 ± 4.0 g kg(-1)) and fiber (276 ± 1.0 g kg(-1)). Extractions of chia nutlets with water at room temperature yielded 38 ± 1.0 g kg(-1) (dry basis) of mucilage. The fresh mucilage structure was similar to a network of open pores. The freeze-dried crude mucilage contained more ash, residual fat and protein than commercial guar and locust bean gum. The solubility of 10.0 g L(-1) w/v solution of chia freeze-dried crude mucilage in water increased with temperature, being maximal at 60 °C (870 g kg(-1)). CONCLUSION The results obtained show a fast exudation of chia mucilage when nutlets are in contact with water. The freeze-dried crude mucilage hydrates easily in water, even at low temperatures. Chia nutlets have mucilaginous substances, with interesting functional properties from a technological and physiological point of view.

Effect of temperature and storage time of wheat germ on the oil tocopherol concentration

Wheat germ represents approximately 3% of the grain and it contains 8-14% oil, which is a rich source of tocopherols (vitamin E) and polyunsaturated fatty acids, mainly linoleic acid. The present work shows the influence of temperature (27oC and 45oC) and storage time (maximum 35 days) of the wheat germ on the concentration of tocopherol in the oil. Their effect on other quality parameters was also investigated. Results indicated that oil oxidation and free fatty acid formation increased markedly with temperature and storage time. The initial sample contained 3134 µg/g total tocopherol, of which 67% was α-tocopherol and, in a lower proportions, β-tocopherol and Γ-tocopherol (30.5% and 2.4%, respectively). In the temperature range studied, tocopherols decreased as a function of storage time following first-order kinetics. The rate constant k for β-tocopherol increased with temperature. The fatty acid composition was not affected by the storage conditions applied.

Moisture-Dependent Engineering Properties of Chia (Salvia hispanica L.) Seeds

Salvia hispanica L., whose common name is chia, is an annual herbaceous plant belonging to the Lamiaceae or Labiatae family. This botanical species, native to southern Mexico and north‐ ern Guatemala, was an important crop in pre-Columbian Mesoamerica in conjunction with corn, beans and amaranth. Chia seeds were valuated not only for food, but also for medi‐ cines and paints [1]. Its cultivation was banned by Spanish conquerors and replaced by exot‐ ic crops (wheat and barley) [2]. Nowadays, chia seeds are being reintroduced to western diets in order to improve human health.

Relationship between oil tocopherol concentration and oil weight per grain in several crop species

The objectives of this work were (i) to analyse the effect of intercepted solar radiation (ISR) per plant during grain filling on oil tocopherol concentration in soybean, maize and rape and (ii) to investigate in these species if variations in oil tocopherol concentration are well accounted for by variations in oil weight per grain. Field experiments were conducted with genotypes of soybean, maize and rape. A genotype of sunflower was included as ‘control species’ as its behaviour was known from previous works. ISR was modified during grain filling by shading or thinning plants. Plants were harvested at physiological maturity and oil tocopherol concentration was determined by high performance liquid chromatography. Samples from other field or growth chamber experiments were also processed. In the four species, increasing radiation increased the oil and tocopherol weight per grain. Increasing ISR reduced oil tocopherol concentration in sunflower, soybean and rape but not in maize. The oil tocopherol concentration would be reduced by ISR in those species, with high oil contents in their grains, where the oil synthesis is more increased than tocopherol synthesis. The variations in oil tocopherol concentration were accounted for by variations in oil weight per grain only in those species with high and variable oil concentration.

Effect of Drying Operating Conditions on Canola Oil Tocopherol Content

The aim of this work was to evaluate two operating parameters of seed drying (temperature and initial moisture content) on the tocopherol content of canola oil. The raw material was characterized by moisture, oil, protein, crude fiber and ash content. Seeds at 13.6% and 22.7% moisture content (dry basis, db) were dried at temperatures in the range of 35–100 °C to a safe storage moisture of 7% db. Oil was extracted from each treated sample. The oil extracted from the samples dried at the extreme temperatures was analyzed by means of the acidity value, peroxide index and fatty acid composition, finding no significant differences among treatments or among untreated and treated samples. Tocopherol contents in the oils obtained for all the assayed temperatures were determined. Differences were found for the samples with 22.7% (db) initial moisture content. Except at 35 °C, temperature affected negatively the oil tocopherol content. However, when 13.6% (db) moisture seeds were processed, no significant differences were observed in the amount of this minor oil component among assays.

Effect of Mucilage Extraction on the Functional Properties of Chia Meals

Chia (Salvia hispanica L.) is an annual herbaceous plant that belongs to the Lamiaceae family, which is native to southern Mexico and northern Guatemala. The Salvia hispanica fruit con‐ sists of four nutlets, similar to an indehiscent achene, which contain a single seed. These nut‐ lets are commonly called “seeds” [1]. Chia seed, together with corn, beans, and amaranth were important crops for pre-Columbian civilizations in America, including the Mayan and Aztec populations [2, 3]. With time its use was abandoned, but by at the end of the last cen‐ tury there was a resurgence of interest in chia due to its nutritional value [4]. Chia is consid‐ ered an alternative crop to diversify and stabilize the economy of Northwestern Argentina [5]. The plant produces numerous small white and dark seeds that mature in autumn [6]. These seeds contain about 30% oil, and they mainly consist of unsaturated fatty acids [4, 7]. Chia seeds are a natural source of omega-3 fatty acids, antioxidants, proteins, vitamins, min‐ erals and dietary fiber [5, 7, 8].

Optimization of mucilage extraction from chia seeds (Salvia hispanica L.) using response surface methodology: Extraction mucilage of chia

BACKGROUND Chia mucilage has potential application as a functional ingredient; advances on maximizing its extraction yield could represent a significant technological and economic impact for the food industry. Thus, first, the effect of mechanical agitation time (1-3 h) on the exudation of chia mucilage was analyzed. Then, response surface methodology was used to determine the optimal combination of the independent variables temperature (15-85 °C) and seed: water ratio (1: 12-1: 40.8 w/v) for the 2 h exudation that give maximum chia mucilage yield. Experiments were designed according to central composite rotatable design. RESULTS A second-order polynomial model predicted the variation in extraction mucilage yield with the variables temperature and seed: water ratio. The optimal operating conditions were found to be temperature 85 °C and a seed: water ratio of 1: 31 (w/v), reaching an experimental extraction yield of 116 ± 0.21 g kg-1 (dry basis). The mucilage obtained exhibited good functional properties, mainly in terms of water-holding capacity, emulsifying activity, and emulsion stability. CONCLUSION The results obtained show that temperature, seed: water ratio, and exudation time are important variables of the process that affect the extraction yield and the quality of the chia mucilage, determined according to its physicochemical and functional properties.

Effect of Different Treatments in Dehulling Ability of Safflower Seeds (Carthamus tinctorius L.)

In the oil industry, partial dehulling of seeds before the oil extraction constitutes a relevant stage of process and this could affect both the quality of the products and the industrial capacity. The decrease of moisture content in seed of oil crops can improve the ability of seed dehulling considerably thus to benefit the process of oil extraction. The dehulling process for safflower seeds is not often utilized due to its low efficiency and difficulties. The objective of this work was to determine the optimum moisture content for the dehulling of the safflower seed considering the fine production during seed dehulling. Another aim was to explore the effect of thermal pre-treatments on the seed dehulling ability. Dehulling ability was defined as the ratio (%) between the proportion of hull mechanically extracted and the real proportion of seed hull. A decrease in the moisture content of seeds increases not only their ability for dehulling but also the amount of fines originated. The optimum moisture for the process (maximum dehulling, minimum fines originated) carried out in one and two stages was the same (3,5%), getting the dehulling of about 37% for the process carried out in one stage and of 79% for the process in two stages. The dehulling ability of safflower seeds was affected, in great measure, for superior temperatures to the reference (21oC), presenting an irregular behavior. The same one implies that for temperature lees of about 100 °C, the dehulling ability is smaller that for reference temperature, increasing quickly for higher temperature. Cooling the safflower seeds previously at -5°C allowed increasing the dehulling ability respect to the obtained at the reference temperature, operating with one or two stages. The obtained results suggest that establishing strategies of handling of the seeds, in the stages of dehulling and extraction of oil, will optimize the process on the whole.