Effects of micronisation on the characteristics and physicochemical properties of insoluble fibres

The effects of micronisation on the characteristics and physicochemical properties of (a) an insoluble fibre‐rich fraction (IFRF) prepared from orange peel and (b) cellulose were studied and compared. The results showed that micronisation techniques such as ball milling, jet milling and high‐pressure micronisation could effectively (P < 0.05) reduce particle sizes to microscale, decrease the bulk density and improve the physicochemical properties (water‐holding capacity, swelling capacity, oil‐holding capacity, cation exchange capacity and glucose adsorption capacity) of IFRF and cellulose to different extents (up to 25‐fold). After micronisation the inhibitory effects of these insoluble fibres towards α‐amylase and pancreatic lipase were significantly increased (up to 5.8‐ and 7.8‐fold respectively) and a redistribution of some fibre components from insoluble to soluble fractions was observed. It was concluded that these micronisation treatments, especially high‐pressure micronisation, could effectively improve the functionalities of IFRF and cellulose, which might then be used as potential fibre‐rich ingredients in functional food applications. Copyright © 2006 Society of Chemical Industry     

Effect of micronisation on dietary fibre content and hydration properties of lotus node powder fractions

Fibre‐rich fractions were obtained from nodes of lotus root and micronised by nine different ball‐milling treatments. The optimum milling conditions were screened out by comparing its effects on physicochemical and hydration properties of micro‐sized particles of lotus node powder fraction (LNPF). The micronisation by ball‐milling treatments was carried out at different speeds (200–400 r min^?1) and time (4–12 h). Ball‐milling treatments could effectively (P < 0.05) pulverise the LNPF particles to different micro‐sizes. As particle size decreased, a redistribution of fibre components from insoluble to soluble fractions was observed. Furthermore, micronisation treatments, especially 12 h at 300 r min^?1, could significantly (P < 0.05) increase the hydration characteristics, as well as impart lightness in colour to different extents. Our findings suggested that micronisation can improve physicochemical and hydration characteristics of the fibre components, which provide an opportunity to improve the utilisation and application of lotus node dietary fibre.     

Water‐holding capacity of insoluble fibre decreases free water and elevates digesta viscosity in the rat

BACKGROUND: The relationships between possible physiological properties of insoluble fibre and the viscosity of digesta are poorly understood. The aim of this study was to investigate the effect of insoluble fibres with different water‐holding capacity, swelling, oil‐holding capacity and cation exchange capacity on gastric, small intestinal and caecal contents in rats fed a semi‐purified diet containing either no fibre (control), 50 g kg^?1 tossa jute fibre or 50 g kg^?1 shiitake fibre. RESULTS: The water‐holding capacity, swelling, oil‐holding capacity and cation exchange capacity of insoluble fibres of tossa jute were higher than those of shiitake (P < 0.001). The order of the viscosities of digesta was control group < shiitake fibre group < tossa jute fibre group in gastric, small intestinal and caecal contents (P < 0.05). The digesta viscosity at a shear rate of 40 s^?1 was strongly correlated with the free water content of digesta (r = ? 0.89; P < 0.01). The free water content of digesta depended on the water‐holding capacity of insoluble fibres represented as a linear function with negative slope (P < 0.001). CONCLUSION: The viscosity of digesta depends on the free water content, and this is reduced by fibre that holds water and can swell. Copyright © 2008 Society of Chemical Industry     

Effects of particle size reduction of insoluble fibres by micron technology on various caecal and faecal indices

BACKGROUND: Previous findings demonstrated that particle size reduction of insoluble fibre materials (i.e. starfruit insoluble fibre‐rich fraction and cellulose) to micro‐sizes effectively enhanced their physicochemical properties, which provided clues to their physiological functions. The aim of the present study was to investigate the effects of particle size reduction of these insoluble fibres by micron technology on indices of bowel health. RESULTS: Feeding of the micronised fibres (9.68–14.3 µm), especially those prepared by high‐pressure micronisation, effectively (P < 0.05) improved various caecal and faecal indices, such as decreasing the caecal ammonia concentration (by 20.0–30.0%), increasing the faecal output (135–150%) and moisture content (143–157%) and lowering the activities of undesired β‐D ‐glucosidase (by 39.2–43.6%) and β‐D ‐glucuronidase (by 71.4–77.5%) in faeces of hamsters. Relationships between physicochemical properties and physiological functions of the micronised fibres were considered. The results also demonstrated that the type, processing and related particle size of insoluble fibres were important factors affecting their physicochemical properties and physiological functions. CONCLUSION: The consumption of micronised insoluble fibres at 5% level might exert a favourable effect on improving various caecal and faecal indices. The results of this study provide some hints on potential applications of micron technology in the food industry. Copyright © 2007 Society of Chemical Industry     

Impact of cell wall‐degrading enzymes on water‐holding capacity and solubility of dietary fibre in rye and wheat bran

BACKGROUND: Rye and wheat bran were treated with several xylanases and endoglucanases, and the effects on physicochemical properties such as solubility, viscosity, water‐holding capacity and particle size as well as the chemical composition of the soluble and insoluble fractions of the bran were studied. A large number of enzymes with well‐defined activities were used. This enabled a comparison between enzymes of different origins and with different activities as well as a comparison between the effects of the enzymes on rye and wheat bran. RESULTS: The xylanases derived from Bacillus subtilis were the most effective in solubilising dietary fibre from wheat and rye bran. There was a tendency for a higher degree of degradation of the soluble or solubilised dietary fibre in rye bran than in wheat bran when treated with most of the enzymes. CONCLUSION: None of the enzymes increased the water‐holding capacity of the bran or the viscosity of the aqueous phase. The content of insoluble material decreased as the dietary fibre was solubilised by the enzymes. The amount of material that may form a network to retain water in the system was thereby decreased. © 2012 Society of Chemical Industry     

Different micronization methods significantly improve the functionality of carrot insoluble fibre

This study was to investigate the effects of different micronization methods, including ball milling, jet milling and high-pressure micronization on the characteristics and various functional properties of carrot insoluble fibre-rich fraction (FRF). The results demonstrated that these treatments could effectively (p < 0.05) pulverize the fibre particles to different micro-sizes. As particle size decreased, the bulk density of the insoluble FRF was significantly (p < 0.05) decreased and a redistribution of fibre components from insoluble to soluble fractions was observed. Furthermore, these treatments, especially the high-pressure micronization, could significantly (p < 0.05) increase the physicochemical properties (e.g., water-holding capacity, swelling capacity, oil-holding capacity and cation-exchange capacity), glucose adsorption capacity, -amylase inhibitory activity and pancreatic lipase inhibitory activity of the insoluble FRF to different extents (from several to 29-fold). Our findings suggested that these micronization treatments would provide an opportunity to improve the functionality of carrot insoluble FRF in food applications.     

Extrusion modifies some physicochemical properties of milk protein concentrate for improved performance in high‐protein nutrition bars

BACKGROUND

Extruded and ground milk protein concentrate powders, specifically those with 800 g kg^–1 protein (i.e. MPC80), imparted softness, cohesion and textural stability to high‐protein nutrition (HPN) bars. The present study evaluated some physicochemical properties of extruded and conventionally produced (i.e. spray‐dried) MPC80 to explain these improvements. Protein chemical changes and aggregations within MPC80‐formulated HPN bars during storage were characterized.

RESULTS

Extruded MPC80 powders had broader particle size distribution (P < 0.05) and smaller volume‐weighted mean diameter (P < 0.05) than the spray‐dried control. Loose, tapped and particle densities increased (P < 0.05) and correspondingly occluded and interstitial air volumes decreased (P < 0.05) after extruding and milling MPC80. Extrusion decreased water holding capacity (P < 0.05) and solubility (P < 0.05), yet improved the wettability (P < 0.05) of MPC80. MPC80 free sulfhydryl (P < 0.05) and free amine (P < 0.05) concentrations decreased after extrusion. Sulfhydryl and amine concentrations changed (P < 0.05) and disulfide‐linked and, more prominently, Maillard‐induced aggregates developed during HPN bar storage.

CONCLUSION

Extrusion and milling together changed the physicochemical properties of MPC80. Chemical changes and protein aggregations occurred in HPN bars prepared with either type of MPC80. Thus, the physicochemical properties of the formulating powder require consideration for desired HPN bar texture and stability. © 2017 Society of Chemical Industry     

Effects of micronization on the physico‐chemical properties of peels of three root and tuber crops

BACKGROUND: The aim of this study was to investigate the effect of micronization on the physicochemical properties of the peels of root and tuber crops, including yam (Dioscorea alata L.), taro (Colocasia esculenta L.) and sweet potato (Ipomea batatas L.). Two continuous milling sections, including hammer milling and ball milling, were applied to three samples to obtain micro‐sized particles of root and tuber peels. The micronization by ball‐milling treatment for 10 h was carried out to investigate the distribution of particle sizes and the changes in physiochemical properties. RESULTS: The results indicate that the peels of three crops appeared to be significantly decreased in particle size after 10 h of ball‐milling treatment. Moreover, the ball‐milling treatments resulted in the redistribution of fiber components from insoluble fiber to soluble fiber. The micronization treatments decreased the bulk density but increased the solubility and water‐holding capacities of the micronized peels. CONCLUSION: Our findings suggested that micronization treatments can improve functional properties of the fiber components of micronized peels, which provide a good source of dietary fiber in food applications. Copyright © 2010 Society of Chemical Industry     

Supplementation of pig diet with algal fibre changes the chemical and physicochemical characteristics of digesta

Seaweed extracts, because of their physicochemical characteristics and potential nutritional value, could provide a new source of dietary fibre. This study investigated changes in seaweed fibres (physicochemical and fermentative properties) in different digestive sites and their effects on digesta (viscosity and hydration properties). Sixteen pigs were adapted to a test diet supplemented with 5% algal fibre (either Palmaria palmata (PP), a poorly viscous soluble xylan; or Eucheuma cottonii (EC), a partly insoluble carrageenan; or Laminaria digitata (LD), a highly viscous soluble alginate) or 5% cellulose (reference fibre). PP did not modify the characteristics of digesta and was fermented in the caecum (pH 6.1 ± 0.4; short‐chain fatty acids measured in digesta, 1409 ± 691 µmol g⁻¹ dry matter). EC and LD were mainly insoluble in the stomach, becoming soluble in the intestine; EC was slightly fermented in the colon, giving a low concentration of short‐chain fatty acids (303 ± 122 µmol g⁻¹ dry matter). Supplementation of the diet with alginate (LD) increased 3.5‐fold the ileal viscosity of digesta and their hydration capacity in the ileum and colon. Thus the physicochemical properties of pig digesta largely depend on the physicochemical properties of the ingested seaweed fibre, the pH and ionic conditions prevailing in the gut, and their fermentability. © 2000 Society of Chemical Industry     

Effects of pineapple pomace fibre on physicochemical properties of composite flour and dough,and consumer acceptance of fibre‐enriched wheat bread

Pineapple pomace fibre (PF, containing 70.2% total dietary fibre) can be added to increase dietary fibre of wheat bread. This study was performed to evaluate effects of PF added at 0, 5 or 10% (wheat flour‐basis) on physicochemical properties of the composite flour (wheat flour as the control, CPF‐5 and CPF‐10, respectively) and its dough, to evaluate consumer acceptance of CPF breads and to identify factors affecting willingness to purchase of CPF breads. Incorporating PF affected rheological and pasting properties of CPF. Water‐ and oil‐holding capacity of CPF increased (P < 0.05) as PF levels increased. Bread made with CPF‐5 was more acceptable than that with CPF‐10; however, it was not significantly different from the control, having similar specific volume and texture, but having about three times higher total dietary fibre than the control (4.4% vs. 1.5%). Product label and health benefit information potentially affected consumers' willingness to purchase of fibre‐enriched bread.     

Influences of pretreatment and drying methods on composition,micro/molecular structures and some health‐related functional characteristics of dietary fibre powder from orange pulp residues

Influences of pretreatment methods (washing, blanching, soaking in ethanol), drying methods (hot air‐drying, infrared‐drying, microwave‐drying) and drying temperature on selected characteristics of dietary fibre powder from orange pulp residues were investigated. Pretreatments improved the hydration properties, oil‐holding capacity and glucose dialysis retardation index, but led to losses of fibres, decreased α‐amylase inhibitory activity and aflatoxin B₁ adsorption capacity. Hydration properties, oil‐holding capacity and glucose uptake depended on the structure and porosity of the fibre, while the ability to inhibit α‐amylase and AFB₁ adsorption depended more on the content and molecular fingerprinting of the fibre. Drying condition did not significantly affect functional properties of the fibre, except for the ability to uptake glucose, inhibit α‐amylase and adsorb AFB₁ (P ≤ 0.05). Hot air‐drying at 60 °C resulted in fibre with the highest ability to decrease the rate of glucose and AFB₁ adsorption.     

Characteristics of fibre‐rich powder and antioxidant activity of pitaya (Hylocereus undatus) peels

The contents of total dietary fibre (TDF), soluble dietary fibre (SDF), insoluble dietary fibre (IDF) and functional properties of fibre‐rich powders (FRP) from pitaya peels with different particle size (FRP80, FRP140 and FRP250) were determined. Results showed that FRP140 had higher TDF (79.37%) and SDF (33.07%) with a balanced ratio of SDF/IDF (1:1.32) and higher water‐holding capacity (54.20 g g^?1), swelling capacity (50.63 mL g^?1), oil‐holding capacity (2.65 g g^?1) and glucose dialysis retardation index (62.83% at 60 min), compared with FRP80 and FRP250. Therefore, physiochemical properties of FRP140 were further investigated. SDF of FRP140 mainly contained rhamnose (4.95%) and galactose (1.98%), with 9.45% galacturonic acid, while IDF dominantly contained xylose (4.76%) and galactose (3.42%), with 18.54% klason lignin. Total phenolic content was 7.75 mg g^?1 and mainly composed of salicylic acid (0.98 mg g^?1) and protocatechuic acid (0.45 mg g^?1). Furthermore, FRP140 showed significant reducing power, DPPH‐scavenging activity and nitrite‐scavenging ability.     

Hydrothermal treatments of two cowpea (Vigna unguiculata L. Walp) varieties: effect of micronisation on physicochemical and structural characteristics

The effects of a hydrothermal treatment consisting of tempering (to 41% moisture) and heating to 153 °C (micronisation) on the structural and physicochemical characteristics of two cowpea varieties were studied. The untreated varieties had similar cooking times, although cooked Bechuana white cowpeas were significantly (P ≤ 0.05) softer and had a higher incidence of splitting than Var. 462 cowpeas. This may be due in part to differences in cotyledon structure affecting water uptake during cooking. The hydrothermal treatment changed the physical structure and chemical properties of the cowpea seeds. This led to significant (P ≤ 0.05) reductions in the cooking time of micronised Bechuana white and Var. 462 cowpeas, by 47 and 36% respectively, as compared with control samples. Micronisation caused physical fissuring of the seed coat and cotyledon and significantly (P ≤ 0.05) reduced the bulk density of treated seeds. These changes in the physical structure significantly (P ≤ 0.05) improved the initial water uptake during soaking and cooking, increased the enzyme‐susceptible starch and reduced the protein solubility and hydration capacity of the cowpea seeds. Cooked (60 min) micronised cowpeas also had significantly (P ≤ 0.05) more splits and a significantly (P ≤ 0.05) softer texture than control samples. Copyright © 2005 Society of Chemical Industry     

三种不同改性方法对甘薯渣不溶性膳食纤维改性效果的研究

该研究采用胶体磨湿法粉碎法、超声波辅助酸法、纤维素酶法3种方法处理甘薯渣不溶性膳食纤维(insoluble dietary fiber,IDF),比较改性前后IDF粒径分布、微观形态,并测定分析其理化性质。结果表明,与未改性甘薯渣IDF相比,3种改性方法改性之后,甘薯渣IDF的粒径、分散指数显著降低(P<0.01),持油力、持水力存在显著差异(P<0.01),吸附亚硝酸盐及胆固醇能力都有不同程度的提升。整体而言,这3种改性方法对甘薯渣IDF改性都有效果,并且胶体磨湿法粉碎法改性对甘薯渣IDF的持油力、持水力、吸附亚硝酸盐及胆固醇能力效果最好。甘薯渣改性的IDF可作为功能性成分应用于多种食品。     

化学改性对连翘不溶性膳食纤维理化性质、结构及乳化稳定性的影响

本试验以连翘为原料,运用双酶法提取连翘中的不溶性膳食纤维（Insoluble Dietary Fiber,IDF）,然后采用羧甲基化（Carboxymethylation,CM）、羟丙基化（Hydroxypropylation,HP）和交联（Cross-linking,CL）改性对提取出的连翘IDF进行化学改性,并对它们的理化性质、结构和乳化特性进行了分析。试验结果表明,改性处理使连翘IDF的持水力降低,持油力显著提高了21%～53%（P<0.05）,CM改性和HP改性使连翘IDF膨胀力提高了约73%。结构表征表明:三种改性处理使连翘IDF颗粒体积明显变小、结构更加疏松、热稳定性提高,且降低了其结晶度。改性对连翘IDF乳液在温度、pH、离子强度稳定性等方面有不同程度的提高,且具有良好的贮藏稳定性,其中经CL改性后的连翘IDF乳液整体稳定性最好。     

Effects of fibre derived from passion fruit seed on the activities of ileum mucosal enzymes and colonic bacterial enzymes in hamsters

Passion fruit, a popular tropical fruit, produces a large quantity of edible seeds as agricultural byproducts after juice extraction. The defatted passion fruit seed (PFS) contained a high level of insoluble fibre (∼90%, w/w) of desirable characteristics and physicochemical properties. Cellulose, pectic substances and hemicellulose were the major structural polysaccharides of the PFS insoluble fibre. In this study, the influence of the PFS insoluble fibre on the activities of ileum mucosal enzymes and colonic bacterial enzymes was investigated. It was found that the incorporation of the PFS insoluble fibre into a fibre‐free diet at 5% level significantly (p < 0.05) enhanced the intestinal amylase activity (137%), reduced the caecal pH (6.22), decreased the caecal ammonia content (−38.6%) and faecal ammonia output (−21.2%), and also decreased the activities of β‐D ‐glucosidase (−37.4%), β‐D ‐glucuronidase (−52.9%), mucinase (−35.5%) and urease (−91.4%) in faeces. Our results suggested that PFS insoluble fibre might exert favourable effects on intestinal health. The fact that PFS insoluble fibre was more effective than cellulose in improving intestinal health suggested it could be exploited as a new functional ingredient to promote intestinal function and health. Copyright © 2005 Society of Chemical Industry     

Effect of micronised oat bran by ultrafine grinding on dietary fibre,texture and rheological characteristic of soft cheese

The purpose of this research was to study the effect of micronised oat bran on dietary fibre, textural and rheological of soft cheese. The soft cheese was processed by using the different particle size oat bran as fibre supplement, and its dietary fibre content, rheological and textural properties were determined. The results show that the micronised oat bran with 5–30 μm particle size was prepared by ultrafine grinding and passed through 60–400 mesh sieves. The soluble dietary fibre content in micronised oat bran soft cheeses was higher than that of the control (untreated oat bran soft cheeses; P < 0.05), with a maximum of 2.65 g per 100 g cheeses when oat bran was ultrafine crushed and passed through 300 mesh sieves, while the content of insoluble dietary fibre was lower than that of the control (P < 0.05). The micronised oat bran soft cheese in fermentation is a typical non-newtonian fluid. G′, G″ and apparent viscosity of soft cheeses were increased with the reduction of oat bran particle size. The chewiness and springiness of micronised soft cheeses were increased with the reduction of oat bran particle size, and were higher than that of the control (P < 0.05). The hardness and cohesiveness of micronised soft cheese were decreased with the reduction of oat bran particle size, the hardness was lower, but the cohesiveness of micronised soft cheese was higher than that of the control (P < 0.05). The 1% micronised oat bran can obtain better processing characteristics and overall acceptability for cheese products.     

Particle Size of Milk Protein Concentrate Powder Affects the Texture of High‐Protein Nutrition Bars During Storage

Milk protein concentrate powder with 85% protein (MPC85) was jet‐milled to give 2 particle size distributions (that is, JM‐Coarse and JM‐Fine) or freeze‐dried (FD), in order to improve the functional properties of MPC85 for use in high‐protein nutrition (HPN) bars. Volume‐weighted mean diameter decreased from 86 μm to 49, 22, and 8 μm in FD, JM‐Coarse, and JM‐Fine, respectively (P < 0.05). The MPC85 powders modified by jet‐milling and freeze‐drying were significantly denser than the control MPC85 (P < 0.05). Volume of occluded air in the modified powders decreased (P < 0.05) by an order of magnitude, yet only FD possessed a lower volume of interstitial air (P < 0.05). Particle size reduction and freeze‐drying MPC85 decreased its water holding capacity and improved its dispersibility by at least 20%. Contact angle measurements showed that these modifications increased initial hydrophobicity and did not improve wettability. HPN bars made from JM‐Fine or FD were firmer by 40 or 17 N, respectively, than the control on day 0 (P < 0.05). HPN bar maximum compressive force increased by 38%, 33%, and 242% after 42 d at 32 °C when formulated with JM‐Fine, FD, or control MPC85, respectively. HPN bars prepared with JM‐Fine were less crumbly than those formulated with control or FD MPC85. Physically altering the particle structure of MPC85 improved its ability to plasticize within HPN bars and this improved their cohesiveness and textural stability.     

Effect of Twin-Screw Extrusion on the Functional Properties of Soya Fibre

Dietary fibre from soya residues (by-products of soya bean curd production) before and after twin-screw extrusion were fractionated into water insoluble, 5 g kg⁻¹ ammonium oxalate insoluble, 40 g kg⁻¹ KOH insoluble and 240 g kg⁻¹ KOH insoluble fractions. The porous property, swelling ability in water, water holding capacity and glucose retardation capacity of each fraction were evaluated. Results showed that extrusion decreased the pore sizes and there were no significant differences between glucose retardation capacity of non-extruded and extruded fibres. The 240 g kg⁻¹ KOH extract of fibre might play a unique role in the functional properties of fibre.     

Effects of roasting on ruminal nutrient degradability of sunflower seed

A study was conducted to determine the effects of roasting sunflower seed using heated particulate medium (heated salt at 250 °C, 60 s contact of salt and sunflower seed and 120 s holding time) on crude protein (CP) fractions, ruminal dry matter (DM) and CP degradabilities, and ruminal disappearance of amino and fatty acids. Two ruminally fistulated cows were used in a randomised complete block design. Roasting of sunflower seed decreased (P < 0.05) soluble protein and increased (P < 0.05) neutral detergent‐insoluble protein with little effect on acid detergent‐insoluble protein. Results of the in situ nylon bag study showed that roasting decreased (P < 0.05) ruminal degradability of DM and CP and increased (P < 0.05) ruminal undegraded CP of sunflower seed. Roasting increased (P < 0.05) intestinal digestibility of ruminal undegraded protein. Ruminal disappearance of all amino acids (following 12 h of incubation) was greater (P < 0.05) for raw than for roasted sunflower seed. Similar results were also observed for ruminal disappearance of fatty acids. It was concluded that roasting of sunflower seed using heated salt decreased ruminal nutrient degradabilities and thus increased the concentrations of amino acids and polyunsaturated fatty acids available for digestion in the small intestine. Copyright © 2003 Society of Chemical Industry