Mabel C. Tomás

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.

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.

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].

Effect of natural antioxidants on the physicochemical properties and stability of freeze-dried microencapsulated chia seed oil: Freeze-dried microparticles with chia seed oil and natural antioxidants

BACKGROUND Chia oil possesses a very high content of polyunsaturated fatty acids, mainly α-linolenic acid. This characteristic makes this oil possess beneficial properties to health but gives it a high susceptibility to the oxidation process. Microencapsulation and the addition of natural antioxidants are alternatives to protect chia oil against oxidative deterioration. The aim of this study was to investigate the physicochemical characteristics and the oxidative stability of chia seed oil microencapsulated with different natural antioxidants (Guardian Chelox, which is a commercial blend of extracts from chamomile and rosemary, and essential oils from Origanum vulgare, Origanum x majoricum, and Mentha spicata) by freeze-drying using sodium caseinate and lactose as wall materials. RESULTS The main physicochemical properties of the microencapsulated chia oil were similar regardless of the presence of antioxidant. The moisture content was 38.1 ± 4.0 g kg-1 ; the microencapsulation efficiency was higher than 85% in all cases. The freeze-drying microencapsulation significantly enhanced (P ≤ 0.05) the oxidative stability of the chia oil. The addition of natural antioxidants conferred chia oil additional protection against lipid oxidation, depending on the type and concentration (500 or 1000 mg kg-1 of the emulsion previous to freeze-drying) of the antioxidant. Among them, Guardian Chelox (1000 mg kg-1 ), presented the highest induction time obtained by the Rancimat accelerated oxidative stability test and the lowest peroxide values after 90 days of storage (33% relative humidity, 25 ± 2 °C). Overall, the microparticles with antioxidants presented a lower degree of yellowing during storage than the control system. CONCLUSION The use of different natural antioxidants confers freeze-dried microencapsulated chia seed oil additional protection against lipid oxidation. This information is relevant for the application of this oil, which is a rich source of omega-3 fatty acids, in the food industry.

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.