Enzymatic extraction of fucoxanthin from brown seaweeds

Brown seaweeds contain a number of bioactive compounds. The xanthophyll, fucoxanthin, has in vivo efficacy against disorders such as type 2 diabetes, obesity and cancer. Organic solvents are traditionally employed to extract fucoxanthin, but carry a toxic chemical and environmental burden. The aim of this study was to optimise a fucoxanthin extraction method using enzymes, water, low‐temperature dehydration and mechanical blending, to produce yields comparable to those achieved with an organic solvent (acetone). Response surface methodology was applied, using Fucus vesiculosus as a model species. A fucoxanthin yield of 0.657 mg g^?1 (dry mass) was obtained from F. vesiculosus blade using the enzymatic method, equivalent to 94% of the acetone‐extracted yield. Optimum extraction parameters were determined to be enzyme‐to‐water ratio 0.52%, seaweed‐to‐water ratio 5.37% and enzyme incubation time 3.05 h. These findings may be applied to the development of value‐added nutraceutical products from seaweed.     

Study of the microbial diversity and antimicrobial properties of Irish edible brown seaweeds

Brown Irish edible seaweeds, Himanthalia elongata, Laminaria sachharina and Laminaria digitata, were evaluated for the microbiota in raw and heat processed form. Raw seaweeds showed complete absence of aerobic mesophiles, halophiles, yeasts and molds. However, heating at 85 °C for 15 min resulted in spore germination. Bacterial counts as high as 10⁷ were observed for aerobic mesophiles and halophiles. Heating above 95 °C for 15 min resulted in complete inactivation of surface microflora. Bacteria belonging to Bacillaceae, Paenibacillaceae, Moraxellaceae and Enterobacteriaceae family were identified by 16S rRNA sequencing. In vitro antimicrobial activity of the methanolic extracts of the seaweed on food pathogenic and food spoilage bacteria were also evaluated. The seaweeds in their raw state had almost 100% inhibition against Listeria monocytogenes; 98% and 93% inhibition was achieved against Pseudomonas aeruginosa by H. elongata and L. saccharina extracts, respectively. Heating the seaweeds resulted in the reduction of antimicrobial activity as compared to raw. The effect was more pronounced against Gram negative bacteria.     

Barley for Brewing: Characteristic Changes during Malting,Brewing and Applications of its By‐Products

ABSTRACT: Barley is the basic raw material for brewing. Its chemical composition, brewing, and technological indices are highly determinative for the beer quality and the economical efficiency of the brewing process. Barley is rich in protein, carbohydrates, dietary fibers, minerals, and vitamins. The presence of nonstarch polysaccharides as mixed linkage (1‐3),(1‐4)‐β‐d ‐glucans and arabinoxylans together with the enzymes are responsible for barley modification. Malting is a complex process that involves many enzymes; important ones are α‐amylase, β‐amylase, α‐glucosidase, and limit dextrinase. During the process of malting and brewing, the by‐products left after separation of the wort are rich in protein, fibers, arabinoxylans, and β‐glucan. This review summarizes and integrates barley grain with respect to nutritional, functional, and compositional changes that take place during malting and brewing. It also explores in‐depth the several by‐products obtained after brewing and their potential for various food applications. Barley brewing by‐products offer an opportunity for cereal‐based baked and extruded products with acceptable sensory and nutritional characteristics.     

Effect of barley flour and freeze-thaw cycles on textural nutritional and functional properties of cookies

Studies were carried out on cookies prepared by incorporating barley flour (10%, 20%, 30%, and 40%) into wheat flour. The cookies were evaluated for their physical, chemical, nutritional, textural and sensory characteristics. All the cookie samples showed high fiber, mineral and protein contents when compared to those from 100% wheat flour. Incorporation of barley flour improved the color of the cookies from pale cream to golden brown. The cookies became crispier as indicated by the reduction in the breaking strength value from 4.94 to 3.29 kg. Considering the color, taste, flavor, surface appearance of the cookies, 30% incorporation of barley flour was found to be optimum giving cookies containing 1.7% β-glucan, 36.6 ppm iron, 31.8 ppm calcium, 22.9 ppm zinc while the texture characteristics showed that 30% barley incorporated cookies had breaking strength of 4.021 kg lower than wheat cookies and also indicating that the product was nutritionally rich as compared to the 100% wheat flour cookies. The incorporation of barley flour increased the antioxidant properties and polyphenolic content and hence increased functional properties of the cookies compared to the control. The prepared product was safe microbiologically as well as chemically upto 6 months of storage in different packaging materials under varying temperature conditions. The cookie dough contained 30% barley flour and 100% wheat flour (control) was allowed to under go frozen storage and freeze-thaw cycles (freeze for 12 h and thaw for 4 h). After each freeze-thaw cycle, cookie dough was evaluated for its texture profile and also dough was baked to prepare cookie and assessed for its physical, textural and sensory characteristics. It was found that cookies prepared after freeze-thawing of dough were crisper than the normal ones.     

Apple pomace as a potential ingredient for the development of new functional foods

Extruded snacks and baked scones were formulated with increasing levels (0–30%) of apple pomace (AP). The incorporation of up to 20% of AP in extruded snacks and in baked scones does not change significantly (P < 0.05) the proximate composition of the final products, except for the content of starch of baked scones. At this level of incorporation, the fibre content, phenolic content and antioxidant capacity (DPPH radical scavenging activity, ferric reducing antioxidant power (FRAP) and β‐carotene/linoleic acid system) increased when compared to the products to which no AP was added. Chlorogenic acid and quercetin were the major phenolic compounds found in the products. Loss of phenolic compounds during heat treatment occurred; however, the DPPH radical scavenging activity of final products was not affected.     

Growth and kinetics of Lactobacillus plantarum in the fermentation of edible Irish brown seaweeds

The aim of the present study was to see the applicability of using brown edible seaweeds as a sole source of nutrition for the growth of lactic acid bacteria. Growth kinetics of lactic acid bacteria (LAB; Lactobacillus plantarum) was studied using three species of edible Irish brown seaweeds Himanthalia elongata, Laminaria digitata and Laminaria saccharina. As part of the screening process, growth of the LAB was carried out on raw and heat treated forms of seaweeds. The seaweed species in their raw state could not support the growth of L. plantarum. Heat treatment resulted in almost 4 times increase in the total sugar content in L. digitata and L. saccharina broth which allowed the growth of L. plantarum for 24 h after which the cell number started decreasing. The Laminaria spp. contains a high content of laminaran polysaccharide which can be fermented by LAB. In case of H. elongata, neither raw nor heat treated forms could be fermented; even though the total sugar content increased 4.6 times upon the application of heat. Kinetics of cell growth, lactic acid and acetic acid production was evaluated at different agitation rates in heat treated seaweeds. A maximum log CFU/ml of 10 was achieved at the end of 16-24 h of fermentation for L. saccharina and L. digitata, respectively. The cell growth increased and lactic acid accumulation decreased as the agitation speed was increased from 0 to 100 rpm. Maximum lactic acid accumulation of 2.5 g/l was achieved under static (0 rpm) conditions. The production of acetic acid was very minimal during the entire course of fermentation. Experimental data was mathematically modelled to optimize the cell growth and lactic acid production with respect to the different rotation conditions. The results of this study present an indication of the potential of fermentation of seaweeds using LAB with a possibility towards the development of a range of functional foods.     

Antioxidant capacity,arabinoxylans content and in vitro glycaemic index of cereal-based snacks incorporated with brewer's spent grain

Extruded snacks and breadsticks were formulated with increasing levels of brewer's spent grain (BSG). The phenolic content increased by 4 and 7 fold with BSG addition in extrudates (40 g/100 g) and in breadsticks (35 g/100 g), respectively. Consequently, antioxidant capacity (DPPH, FRAP) also increased despite a recorded loss of phenolic compounds in extruded snacks. Arabinoxylans content increased up to 20 and 25 g of BSG addition/100 g of formulated extruded snacks and breadsticks, respectively. Further addition of BSG did not improve the content of arabinoxylans due to the possible formation of polysaccharide–protein complexes. Medium GI breadsticks were obtained with 35 g of BSG incorporation/100 g formulation. Phenolic content, arabinoxylans content and antioxidant capacity increased in the final products with BSG addition while the glycaemic response decreased. BSG can be incorporated as an ingredient in the formulation of extruded snacks and breadsticks generating products richer in antioxidants and fibre and with low GI.     

Comparative Study of Quality Changes Occurring on Dehydration and Rehydration of Cooked Chickpeas (Cicer Arietinum L.) Subjected to Combined Microwave–Convective and Convective Hot Air Dehydration

ABSTRACT:  Convective hot air dehydration (100 °C) of cooked chickpeas was compared with the combination of microwave–convective hot air dehydration, in terms of microstructure, density, color, texture, dehydration, and rehydration. In the combined drying experiments, 2 levels of microwave power (100 W and 200 W) were investigated, combined continuously with convective air drying at 100 °C. Compared with convective hot air drying, combination drying led to a considerable reduction in dehydration time. Combination drying also improved the porosity of the finished dehydrated product, leading to faster rehydration kinetics. Cryogenic scanning electron microscopy micrographs showed that chickpeas subjected to combined drying experienced less shrinkage than those dried by convective hot air. Combination drying at the higher (200 W) level produced a darker ( P < 0.05) rehydrated product with significantly lower relative rehydrated moisture content ( P < 0.05) when compared with the lower (100 W) level of combination drying.     

Effect of different rehydration temperatures on the moisture,content of phenolic compounds,antioxidant capacity and textural properties of edible Irish brown seaweed

The effect of temperature (20, 40, 60, 80 and 100 °C) on the rehydration kinetics and phytochemical constituents of dried edible Irish brown seaweed, Himanthalia elongata, were studied. The moisture content of fresh and dried seaweed was 4.07 and 0.07 g water/g dry basis, representing a 98.1% reduction in water content. All rehydration moisture curves had a clear exponential tendency, and it was observed that the rehydration time decreased when temperature was increased. Although restoration of the product to its original moisture content was achieved, rehydration resulted in losses in phytochemical content. Moisture equilibrium was achieved fastest at 100 °C (40 min) with losses of 83.2 and 93% in the total phenol and total flavonoid contents, respectively. The moisture content was fitted to empirical kinetic models; Weibull, Peleg’s, first-order and exponential association. Activation energies of 4.03, 4.28 and 3.90 kJ/mol were obtained for the parameters of Peleg’s, first-order and exponential models, respectively.     

Kinetic evaluation of colour, texture, polyphenols and antioxidant capacity of Irish York cabbage after blanching treatment

York cabbage was blanched between 80 and 100 °C with an increment of 5 °C for up to 14 min and kinetics of the different physicochemical properties were studied. Significant reductions in the texture, colour, polyphenols (PPs) and antioxidant (AO) capacity were observed due to blanching. Total phenolic and flavonoid content retained ranged from 19.6-24.5% to 22.0-25.7%, respectively. Heavy losses in the AO capacity of 74.0-82.0% also occurred as a result of blanching. Blanching caused a significant reduction in firmness of 24.0-73.2% and a similar trend was also observed for colour. Kinetic evaluation of degradation was carried out for all the studied quality parameters. The fractional conversion first-order reaction model showed a good fit for the different studied parameters, with coefficients of determination ranging from 0.892 to 0.992, except for texture and colour, which followed first order and zero order kinetics, respectively. The temperature effect followed the Arrhenius law, with activation energies for polyphenolic content, AO capacity, colour and texture calculated as 9.22-11.5, 9.05-35.05, 15.73 and 33.8 kJ/mol K, respectively.