Fruit‐based functional foods I: production of food‐grade apple fibre ingredients

Abstract

With the increased consumer interest in fibre-enriched functional foods, industrial-scale methods for functional fibre production are demanded. The development of a food-grade fibre preparation method at lab scale that is feasible for industrial scale-up is a pre-requisite. This paper describes two lab-scale fibre preparation methods that have potential to be scaled up to industrial setting for the production of fruit fibres containing desired bioactives and functionality. The two methods, one aqueous and the other ethanolic, were used to isolate fibres from Granny Smith apples (Malus domestica Borkh cv. 'Granny Smith'). In the aqueous method, ground apple tissues were suspended in HEPES buffer (20 mM, pH 6.5), and then mechanically ruptured using an Ultra-Turrax and ring grinder. Between steps, the cell-wall materials were washed with the HEPES buffer. In the ethanolic method, ground apple tissues were stirred in 72% ethanol at 4°C, filtered, resuspended in 72% ethanol and then washed. Microscopic examination and chemical analysis were performed on the resultant fibres. The aqueous method produced natural and uniform dietary fibres in the form of plant cell walls containing 0.282 g uronic acid per g dried fibre. By comparisons, the ethanolic method produced crude fibres containing only 0.182 g uronic acid per g dried fibre, the lower uronic acid content indicating the presence of impurities. Thus, the aqueous method appeared to be advantageous in terms of the retained pectic polysaccharide content and cost-effectness for industrial scale-up. Further characterisation using Folin-Ciocalteu assay and high performance liquid chromatography indicates that the fibres obtained by the aqueous method contained significant amounts of phenolic compounds (2.6 mg catechin equivalent per g dried fibre). These results suggest that fibres obtained by the aqueous method may be more suitable for functional food applications where fibres with high pectic polysaccharide and beneficial phenolic antioxidants are preferred.

Evaluation of the extraction efficiency for polyphenol extracts from by‐products of green kiwifruit juicing

“…, 1998), the degree of substitution and the location in the plant tissues (Fry, 1988). Although both ethanolic and aqueous extractions have previously been used for pectin preparation, ethanolic extraction was found to alter the solubility of pectic polysaccharides and co‐precipitate other compounds (Fry, 1988; Sasaki & Nagahashi, 1989; Sun‐Waterhouse et al. , 2008a,b,c).…”

Quality of granola prepared with dried caju-do-cerrado (Anacardium othonianum Rizz) and baru almonds (Dipteryx alata Vog)

“…The heterogeneity and the combination of these foods makes it possible to include other ingredients, thus providing granola with large amounts of dietary fiber, energy, vitamins and minerals, proteins, carbohydrates and unsaturated fatty acids (AmayaFarfan et al 2005;Waterhouse et al 2008).…”

In vitro prebiotic activities of tamarillo (Solanum betaceum Cav.) hydrocolloids

“…The procedure for the water extraction was similar to that for the citric acid extraction except that water was used as the extraction solution and the extraction was performed at 50°C. The HEPES buffer and ethanol extractions were performed using a method described by Sun-Waterhouse, Farr, Wibisono, and Saleh (2008) with some modifications. Puree was suspended in HEPES buffer (20 mM, pH 6.5) in a 1:4 (w/v) puree to HEPES buffer ratio with continuous stirring for 30 min at 25°C.…”