Food wastes as natural sources of lactic acid bacterial exopolysaccharides for the functional food industry: A review.

Exopolysaccharides (EPSs) synthesized by lactic acid bacteria (LAB), have recently received much interest because of their various functional features in several industries. Food wastes (FWs) have become a major source of worry, as they can cause serious environmental contamination if improperly disposed. The utilization of these FWs is an excellent choice (approach) for producing value-added products such as EPSs, which will efficiently remediate wastes. The overall EPSs yield for the selected producers is strain-specific, and is heavily influenced by the nutritional and growing conditions used. This review emphasizes what is currently known about LAB's ability to generate economically relevant EPSs from FWs. In addition, a concise overview of the food industry, packaging, pharmaceutical and clinical applications application is discussed.

Composition of Phenolic Acids and Antioxidant Properties of Selected Pulses Cooked with Different Heating Conditions.

Pulses are recommended for healthy eating due to their high content of nutrients and bioactive compounds that can undergo changes during cooking. This study investigated the effects of four cooking methods (boiling, pressure, microwave, slow) and three heating solutions (water, salt, sugar) on the phenolic acids and antioxidant properties of three pulses (faba beans, lentils, peas). The composition of phenolic acids differed among the three pulses with p-coumaric and ferulic being the dominant acids. Cooking increased free phenolic acids and lessened bound phenolic acids in faba beans and peas, while decreased both free and bound phenolic acids in lentils. Cooking resulted in reductions in total phenol content (TPC) in faba bean methanol and bound extracts. Pressure and microwave cooking increased TPC in lentil methanol extracts, while pot boiling and slow cooking reduced TPC. Microwave cooking resulted in increases in TPC in bound phenolic extracts from lentils. For peas, cooking increased TPC in both methanol and bound phenolic extracts. Significant changes were also observed in the antioxidant capacity of cooked pulses based on the scavenging ability of DPPH, ABTS and peroxyl radicals subject to the type of pulse, polyphenol and antioxidant assay. Despite the significant reduction in antioxidants, high amounts of phenolics with potent antioxidant activities are still found in cooked pulses.

Characterisation of several types of millets as functional food ingredients.

Millets can be sustainable food sources in future agronomy because of its ability to flourish in harsh climatic conditions, however limited studies exist on the nutritional and hypoglycaemic properties of millets. This study is intended to identify millets as potential functional food ingredients based on their nutrient profile and in vitro starch digestibility. Seven millet types exhibiting diverse structures and compositions were investigated. Chemical composition revealed that depending on the millet type, millets are excellent sources of insoluble dietary fibre, lipids and minerals, these components had values ranging from 9.3-56.7 mg/g, 11.5-31.7% and 2.1-8.0%, respectively. Linoleic and oleic were the major unsaturated fatty acids detected in all the millet types. Millets were also found to be rich in free and bound phenolic acids. Kodo millet was found to have the highest free and bound phenolic contents. Expected glycemic index of millets ranged between 42.7 and 58.3, hence making them some valuable low GI food sources for diabetics. The obtained results may suggest that millets with its superior nutrient profile and hypoglycaemic property could be a promising ingredient for the functional food industry.

Effect of parboiling on decortication yield of millet grains and phenolic acids and in vitro digestibility of selected millet products.

Parboiling is a common method used in rice processing to improve milling yield and physicochemical properties. The current study evaluates parboiling as a pre-treatment step in millet decortication and its impact on phenolic profile and in vitro digestibility of two traditional millet products, steam-cooked couscous and porridge, made from pearl (Pennisetum glaucum) and proso (Panicum miliaceum) millets. Parboiling increased decorticated yield of pearl and proso millet by 37% and 28% respectively. It resulted in significant (P < 0.05) rise in free and bound phenolic contents and DPPH (2,2-diphenyl-1- picrylhydrazyl) radical scavenging activity of the millet products. This method significantly (P < 0.05) changed starch digestion fractions of both products thereby reducing expected glycemic index (eGI) while the in vitro protein digestibility of products decreased by 14-17%. Parboiling could be an effective way to improve millet decortication yield as well as produce millet products with higher phenolic acids antioxidant activity and lower GI.

Rheological properties and bread quality of frozen yeast-dough with added wheat fiber.

BACKGROUND: The rheological characteristics of frozen dough are of great importance in bread-making quality. The effect of addition of commercial wheat aleurone and bran on rheological properties and final bread quality of frozen dough was studied. Wheat aleurone (A) and bran (B) containing 240 g kg-1 and 200 g kg-1 arabinoxylan (AX), respectively, were incorporated into refined wheat flour at 150 g kg-1 substitution level (composite A and B, respectively). Dough samples of composite A and B in addition to two reference dough samples, refined flour (ref A) and whole wheat flour (ref B) were stored at -18°C for 9 weeks. RESULT: Frozen stored composite dough samples contained higher amounts of bound water, less freezable water and exhibited fewer modifications in gluten network during frozen storage based on data from differential scanning calorimetry and nuclear magnetic resonance spectroscopy. Bread made from composite frozen dough had higher loaf volume compared to ref A or ref B throughout the storage period. CONCLUSION: The incorporation of wheat fiber into refined wheat flour produced dough with minimum alterations in its rheological properties during 9 weeks of frozen storage compared to refined and 100% wheat flour dough samples. © 2016 Society of Chemical Industry.

On the molecular structure of the amylopectin fraction isolated from "high-amylose" ae maize starches.

The amylopectin fractions from starch of a series of amylose-extender (ae) maize samples (HYLON(®) V, VII and VIII starches) were isolated and analysed for their molecular composition and structure. The fractions from all samples contained both a high and a low molecular weight fraction (HMF and LMF), of which LMF increased with the amylose content of the starch and appeared to have substantially more of long chains than HMF. A normal amylose-containing maize starch (NMS), which served as a reference sample, contained very little LMF, which suggested that LMF was the inherent result of the effect of the loss of starch branching enzyme IIb activity in the ae mutants. Clusters were isolated from the amylopectin fractions using Bacillus amyloliquefaciens α-amylase, which effectively hydrolyses long internal chain segments between clusters. During the hydrolysis process, clearly more of small dextrins were released from the ae starches in comparison to NMS. It appeared that some of these small dextrins did not precipitate in methanol together with the majority of the clusters. Nevertheless, isolated clusters from the HYLON starch samples were smaller than in NMS and the clusters possessed a lower density of branches with longer chains. The composition of small, branched building blocks was also clearly different: HYLON starch samples possessed much more of single-branched blocks and less multiple-branched blocks than NMS.

Effect of ß-glucan-rich barley flour fraction on rheology and quality of frozen yeasted dough.

Research has shown that prolonged frozen storage of bread dough reduces the quality of the end product. In this study, the effect of air-classified barley flour fraction rich in ß-glucan (approximately 25%) on rheology and quality of frozen yeasted bread dough was investigated. Wheat flour (W) was replaced by air-classified barley flour fraction (B) at 10% without or with 1.4% vital gluten to produce ß-glucan enriched barley dough (WB) or barley dough plus gluten (WB + G). Dough products were stored at -18 ºC for 8 wk and their rheological properties were investigated weekly. During frozen storage dough extensibility increased, while elastic and viscous moduli decreased. Differential scanning calorimeter and nuclear magnetic resonance data indicated that WB and WB + G dough products contained approximately 10% less freezable water and 9% more bound water compared to the control dough (W). ß-Glucan enriched dough also exhibited less changes in gluten network as shown by SEM photographs. The addition of air-classified barley flour fraction at 10% in frozen dough reduced deterioration effects caused by frozen storage via minimizing water redistribution and maintaining rheological properties of frozen dough.

The impact of milling and thermal processing on phenolic compounds in cereal grains.

Consumption of wholegrain foods has been recommended for healthy diets. The beneficial health properties of wholegrain products have been associated with the presence of higher amounts of dietary fiber and antioxidants and lower calories as compared to their respective refined ones. Phenolic compounds are mainly attributed to antioxidant properties of wholegrain foods. This review article provides a single comprehensive source that describes effects of milling and thermal processing on phenolic compounds and antioxidant properties in cereals. In general, milling and pearling processes affect the distribution of phenolic, compounds and thus antioxidant properties vary among the milling fractions. Thermal processes such as baking and extrusion could cause negative or positive effects on phenolic compounds and antioxidant properties of the end product subject to grain type and processing conditions. Thus factors that enhance health benefits of wholegrain cereal products have been discussed.

Mechanism of hydrolysis of native and cooked starches from different botanical sources in the presence of tea extracts.

A series of experiments were conducted to highlight the mechanism of inhibition of hydrolysis and differences in hydrolysis among starches from different sources in the presence of green or black tea extract. The first experiment showed that black tea extract was more effective at reducing final viscosity for all starches. The second experiment showed that black tea was more effective at inhibiting starch hydrolysis compared to green tea when starch, tea extract, and pancreatin were added at the beginning of pasting. The third experiment, when starches were pretreated with tea extracts, showed that both treatments reduced starch hydrolysis. Analysis of supernatant free phenolic content and of soluble dextrins showed that amyloglucosidase activity was affected, with exceptions for potato starch. These observations suggest that starch hydrolysis is affected by interactions and also by the impact on specific enzymes based on starch structure.