Paul Ainsworth

Effect of fermented/germinated cowpea flour addition on the rheological and baking properties of wheat flour

There is a growing interest in fortifying wheat flour with high lysine material, such as cowpea flour, to improve the essential amino acid balance of baked food products. The use of cowpeas as a food source has not been utilised fully, especially in developed countries. In this research, wheat flour in a standard bread formulation was partially replaced with cowpea flour, germinated cowpea flour and fermented cowpea flour at levels of 5%, 10%, 15% and 20% (wt/wt). Composite flours were analysed for ash, protein, gluten contents and α-amylase activity as well as colour, farinograph and extensograph characteristics. Bread baked from composite flours was analysed for loaf volume and weight, texture, crumb-grain structure and colour. Increasing levels of cowpea flour in the blends resulted in changed flour characteristics such as ash and protein contents and colour. It also changed farinograph and extensograph characteristics, mainly by increased water absorption. Incorporation of cowpea flour exerted a certain volume depressing effect on the bread and gave a compact structure at higher substitution levels. Overall acceptable results were obtained based on characteristics of control bread.

The effect of fermentation conditions on the nutrients and acceptability of tarhana

Abstract A laboratory method was evaluated for the production of tarhana, a popular Turkish fermented wheat-yogurt mixture. The changes in pH, the total titratable acidity and the vitamin content (thiamine, riboflavin and vitamin B12) of tarhana of different formulations (type of wheat flour, amount of yogurt and presence of salt) were monitored during fermentation. Chemical composition and acceptability of laboratory-produced tarhana were compared with those of authentic homemade and commercially produced tarhana. The pH and titratable acidity of tarhana samples did not change after the third day in the course of a 4-day fermentation. The final pH and acidity (expressed as percent lactic acid) of tarhana were found to be in the range of 4.3–4.8 and 1.8–2.3 (dry basis), respectively. The thiamine, riboflavin and vitamin B12 contents of tarhana did not change considerably during fermentation. The addition of salt to tarhana lowered the acid formation rate during fermentation, leading to a higher pH. The replacement of white wheat flour with wholemeal flour resulted in an expected increase in the protein and vitamin content of tarhana; however, a decrease in overall acceptability was observed.

The effect of different enzymes on the quality of high-fibre enriched brewer's spent grain breads

The brewing industry produces large quantities of waste co-products. There is increasing pressure to ensure total utilisation of such products to address economic and environmental concerns. Brewers spent grain (BSG) the main by-product of the brewing industry is rich in dietary fibre and has a strong potential to be recycled. The overall objective of this study was to incorporate BSG into wheat flour breads together with a range of different enzymes (Maxlife 85, Lipopan Extra, Pentopan Mono BG and Celluclast) and evaluate the bread quality. A number of nutritional and textural properties of the finished product were studied. The incorporation of BSG significantly (P<0.0001) improved the dietary fibre but the major difficulty encounted was to achieve a good structure and high loaf volume. Increasing the level of dietary fibre significantly (P<0.001) increased dough development time, dough stability and crumb firmness but decreased the degree of softening and loaf volume. It was found that addition of Lipopan Extra (LE), Pentopan Mono (PE) and a mixture of Pentopan Mono and Celluclast (PCE) enzymes improved the texture, loaf volume and shelf life while Maxlife 85 enzyme (ME) was not significantly different from control samples (wheat flour breads containing 0%, 10%, 20% and 30% BSG). Image analysis of the bread structure obtained from the C-cell analyzer showed that the most significantly (P<0.001) open network was obtained using LE, followed by PE and PCE.

Effect of different ingredients on the fermentation activity in tarhana

Abstract Tarhana is a fermented wheat flour–yoghurt mixture which is widely consumed in Turkey. Bakers yeast is also involved in the fermentation. In this study, fermentation activity of tarhana was investigated by monitoring the lactic acid bacteria and yeast population when the level of salt and amount of yoghurt used were varied. Fermentation activity was high during the first day of fermentation. Microbial counts dropped below the initial counts at the end of a 4-day fermentation. Fermentation activity of tarhana prepared without salt was found to be higher than the tarhana samples prepared with salt.

Extrusion of tarhana: effect of operating variables on starch gelatinization

Tarhana, a traditional Turkish cereal food, was extruded using a twin-screw extruder. The effect of barrel temperature (6–120 °C), feed rate (10–20 kg h−1, wet basis) and screw speed (100–300 rpm) on starch gelatinization was investigated using response surface methodology at constant moisture content (43%, wet basis). A regression equation for predicting starch gelatinization was developed. Barrel temperature had the most pronounced effect on starch gelatinization at constant moisture content, followed by feed rate and screw speed. Response surface plots suggest that a high degree of starch gelatinization can be achieved when tarhana is extruded at high barrel temperatures and screw speeds but low feed rates (i.e. high residence times).

New food product development: strategies for success?

This paper seeks to evaluate the ideas of six new product development (NPD) theorists and their associates. These include those who have developed their theories with particular reference to the food industry and the development of new food products. Their ideas are contrasted with non‐food specific theorists; these include those interested in the management of new products and those involved in marketing who have recognised the important role that NPD plays in any business. A further viewpoint is taken from theorists who are interested in NPD per se and who use food, on occasions, to illustrate their ideas. This research identifies different theories and recognises that there is very little consensus as to the right and wrong way to manage the process of product development. Indeed theorists name and number their various stages or phases differently with some advocating five while others believe eight steps to be more appropriate. This research concludes that an organisation should not be tied to one particular model but should take on board the basic fundamentals of a food‐based model (theory) and adapt and amend it to their particular situations as and when they develop new food products.

Growth of Pseudomonas fluorescens and Candida sake in homogenized mushrooms under modified atmosphere

Abstract Pseudomonas fluorescens and Candida sake were inoculated into mushrooms and stored under different gaseous atmospheres: air, CO 2 :N 2 :O 2 (25:74:1%) and CO 2 :N 2 :O 2 (50:49:1%). The growth of both microorganisms was measured during 18 days of storage at 5 and 10 °C. The percentages of O 2 and CO 2 inside the package and the pH of mushrooms were monitored during the storage. The maximum specific growth rate constant ( μ m ), lag time ( λ ) and maximum population density ( A ) were evaluated from the modified Gompertz model using non-linear regression. The percentage of O 2 in the samples stored in air decreased progressively during an 18-day storage while the percentage of CO 2 increased. The pH of the samples stored under CO 2 decreased whereas the pH of samples stored in air at 10 °C increased during the first 4 days followed by a decrease for the rest of the storage. The lag time increased with an increase in the percentage of CO 2 in the atmosphere. The results suggest that the modified Gompertz model can be used successfully to describe the growth of both C. sake and P. fluorescens in mushrooms. Low CO 2 /high storage temperature combinations were found to favor the growth for both microorganisms.

Ascorbic acid loss in vegetables: adequacy of a hospital cook-chill system.

A method for in vitro determination of available calcium, iron and zinc content from infant food after digestion was evaluated. This method introduced an intraluminal digestive phase, adapted to the gastrointestinal conditions of infants younger than 6 months of age, prior to continuous flow dialysis of the resultant gastric digest. Precautions handling the method were discussed and enzymatic parameters were defined. Ruggedness of the method was determined from the availability of calcium, iron and zinc at different gastrointestinal conditions. Availability of all three elements was higher at gastric pH of 2 (20.0 ± 1.1% for calcium, 4.06 ± 0.66% for iron and 17.5 ± 1.3% for zinc), than from the normal procedure (pH 4) (15.6 ± 1.2% for calcium, 1.18 ± 0.26% for iron and 8.2 ± 0.9% for zinc). At pH 5, however, calcium availability appeared to be lower (11.7 ± 1.0%) (P < 0.05). The intestinal pH also had a major influence on the availability. At low intestinal pH (5.5), availability was 40.5 ± 2.3% for calcium, 3.01 ± 0.58% for iron and 26.8 ± 1.8% for zinc, which was higher compared with the normal procedure (P < 0.05). Moreover, other factors, such as digestion time, mixing and filtration pressure, also affected the availability. Recovery tests yielded mean values of 94 ± 3% for calcium, 109 ± 9% for iron and 106 ± 4% for zinc. Mean intra- and inter-batch precision of the availability procedure was 4.1 CV% and 6.6 CV% for calcium, 14.5 CV% and 19.2 CV% for iron, and 4.0 CV% and 13.6 CV% for zinc. The method provides adequate accuracy, acceptable precision and good recovery. It offers the advantage of being simple, rapid and inexpensive, since it takes only 1 day to run the whole availability procedure (including four replicates per sample), and the low costs of the dialysis equipment. It can therefore be considered as suitable for predicting the availability of essential elements from foods used during the first months of infancy.This research evaluates the ascorbic acid loss of vegetables prepared in a hospital cook-chill plated system. The ascorbic acid loss of three vegetable samples (carrots, peas and potatoes) were measured at various points in the cook-chill system and analysed using the DCPIP method. Substantial losses for all vegetables were identified at the cooking and regeneration stages. The ascorbic acid levels of the selected vegetables when raw ranged from 6 to 10 mg/100 g sample. At the end of the food service cycle the ascorbic acid content of the vegetables was reduced to 1.7-5.8 mg/100 g sample. The largest percentage loss of ascorbic acid, i.e. 76%, was found in mashed potatoes. Peas incurred the least percentage loss, i.e. 42%. This progressive deterioration during the cook-chill plated catering system causes an insubstantial presence of ascorbic acid in the food served to hospitalised patients.

Influence of process variables on residence time distribution and flow patterns of tarhana in a twin-screw extruder

Abstract The effects of feed rate (10–20 kg/h) and screw speed (100–300 rpm) on the residence time distribution (RTD) were studied in the extrusion of tarhana in a twin-screw extruder. The Peclet number ( Pe ) was used to determine the extent of axial mixing in the extruder. Increasing the screw speed or feed rate reduced the mean residence time ( t m ). Feed rate had more effect on t m than screw speed. The value of Pe varied from 1.1 to 8.7. The flow in the extruder approached plug flow as the feed rate was increased or the screw speed was decreased.

Preparation of modified fats from vegetable oil and fully hydrogenated vegetable oil by randomization with alkali catalysts

Randomization of fat blends, formulated by mixing vegetable oil with fully hydrogenated vegetable oil in various ratios, using alkali catalysts, have been investigated. The relationship between the structure and physical properties was examined. The fatty acid and triacylglycerol composition of each original fat blend and the randomization products together with the physical properties such as melting, crystallization characteristics and solid fat content were correlated. The differences in the exothermic and endothermic peak temperatures, melting points and solid fat content among the fat blends showed the effects of the composition on the physical properties.