An apple and dairy based ready-dessert with an added prebiotic was stored and chill temperatures and number of quality attributes were monitored during chill (4 °C) storage for 30 days. All ready-desserts were thermally processed by sous vide ( P90 > 10 min). The stability of the dairy component in ready-desserts was monitored by measuring volatile free fatty acids. Changes in these components were more evident in prebiotic-enriched samples compared to controls. However, no significant differences were observed over storage in control and prebiotic-enriched ready-desserts. This was supported by sensory analysis that showed no significant changes over storage in control or prebiotic-enriched samples. Of the other quality parameters, the addition of prebiotic inclusions resulted in lower L and b values and dry matter ( p < 0.05), while increasing ( p < 0.05) soluble solids content compared to control samples. Fluctuations in some of the quality parameters were also observed over storage. Rheological characteristics, i.e. flow behaviour ( n), consistency index ( K), storage ( G′), loss ( G″) and complex ( G*) moduli were unaffected by prebiotic inclusion. However, storage affected the rheological characteristics of ready-desserts. A decrease ( p < 0.05) in flow behaviour ( n) led to concomitant increases in consistency index ( K) and complex modulus ( G*) values in control samples.

Antioxidant activity and quality parameters of skin-on apple wedges from 10 cultivars were examined during chill storage and over two growing seasons. Storage of fresh-cut apple wedges had a significant impact on quality parameter indices such as browning index (p < 0.001) and texture firmness (p < 0.001). Headspace gas analysis indicated that the degree of browning negatively correlated to oxygen (-0.69) and positively (0.70) correlated to carbon dioxide levels. Antioxidant capacity as assessed by three in vitro methods (DPPH, FRAP and ORAC) decreased significantly for 9 of the 10 cultivars after 5 days of storage at 3 ± 1 °C (p < 0.001). These indices increased in case of Shampion apples over the same storage period for all three assays. With regard to antioxidant capacity and quality parameters, the cultivars Gloster, Alwa, Idared and Jonica were the best performing overall and could therefore be recommended as a core ingredient in fresh-cut fruit products.

SummaryThe effect of vacuum impregnation (VI) of fresh‐cut apple wedges with honey, in presence and absence of a browning inhibitor on physicochemical, sensory and antioxidant properties over 7 days of storage at 2–4 °C was studied. Infusion of wedges with honey resulted in very little weight change indicating loss of internal water and ingress of honey carbohydrates into the wedges, hence the correlation coefficients with soluble solids content (r = −0.91) and dry matter (r = −0.77). Water infused samples showed the highest water uptake resulting in an increase in weight of 30%. Browning (P < 0.001) and firmness (P < 0.001) of apple wedges were the quality parameters most affected by VI. Samples dipped in browning inhibitor prior AS1 showed slightly better performance than undipped wedges with regard to browning and firmness. Total phenol content and antioxidant activity were significantly (P < 0.001) lower for honey infused apple wedges.

Ready-desserts are showing growth potential in the market place. This study involved the testing of desserts (processed apple wedges) produced from 12 apple cultivars (Elstar, Jonagold, Shampion, Jonica, Alwa, Rajka, Gloster, Cortland, Bramley, Braeburn, Gala and Granny Smith) using three processes (chill, freeze-chill, sous vide). Apple wedges were dipped (2 min) in AS1 browning inhibitor (6% w/w). Sous vide wedges were processed (Barriquand Steriflow retort: P-90 > 10 min), while chilled and freeze-chilled wedges were microwaved (700 W for 1-1.75 min) and vacuum packed. The latter were blast frozen (3.75 m/s; -30 degrees C; 2h), stored (-20 degrees C) and thawed at 2-4 degrees C for testing. Chilled and sous vide wedges were held at 2-4 degrees C for 2d. Ranges in values (day 2) were: drip loss 4.5 (Bramley) to 11.6% (Gala) (P < 0.01); white/yellow (L/b) ratio 2.7 (Bramley) to 4.3 (Alwa) (P < 0.001); shear values 0.29 (Jonagold) to 1.2 kN/100 g (Alwa) (P < 0.001). Data for chill, freeze-chill and sous vide samples were: drip loss 7.2, 13.7, 5.4% (P < 0.001); shear 1.0, 1.0, 0.73 kN/100 g (P < 0.001). Sensory tests on the sous vide samples showed that all cultivars received average acceptability with the exception of wedges from Rajka, which were downgraded. A range of processed ready-desserts has been successfully produced from 12 apple cultivars.

Prevention of browning in fresh-cut fruit is of major commercial significance as fresh-cut fruit salads are major players in the international marketplace. Natureseal (R) AS1 and AS5 browning inhibitors out-performed ascorbic acid and citric acid in tests with fresh-cut wedges of 'Bramley' apple. A dipping regime of 2 min in 6% (w/v) AS1 solution was found to be optimal, as longer dip-times and higher concentrations led to significant residues of AS1 on the fresh-cut 'Bramley' wedges. Tests on fresh-cut wedges from ten apple cultivars indicated that AS1 was significantly beneficial (P < 0.001) to maintain wedge colour during chill-storage in all cultivars, with the exception of 'Shampion', which had a low browning tendency and performed equally well with or without AS1. Tests on the anti-oxidant status of a generic fruit salad, which was not treated with AS1 and stored for 15 d, indicated a significant reduction in anti-oxidant status, due largely to the depletion of vitamin C (from 137 to 97 mg 100 g(-1) DW). Total phenolics contents remained relatively constant over the 15-d storage period. The outcomes from these trials have been presented to commercial food companies with a view to their uptake.

The alditol acetate derivatisation for determining levels of reducing sugars in ethanolic extracts from potato tubers by gas chromatography was investigated. Standard curves for alditol acetate derivatives of aqueous solutions of allose, glucose and fructose were of acceptable linearity over the concentration range of interest (R2=0.9933, 0.9992 and 0.9997, respectively). Reproducibility of replicate derivatisation of the standards was also acceptable [mean relative standard deviation (RSD) was 5.16%]. Fructose was converted to mannitol and glucitol hexa-acetate in a fixed proportion (mean mannitol:glucitol ratio was 0.67) over the concentration range applicable to potatoes. This ratio was used to calculate reducing sugar levels in ethanolic extracts from five varieties of potatoes using allose as an internal standard. Reproducibility for replicate analyses of reducing sugars in potatoes was acceptable (Mean RSD=6.65%) and values were within the range of those reported previously.

: The incidence of coeliac disease, or other allergic reactions/intolerances to gluten is increasing, largely due to improved diagnostic procedures and changes in eating habits. The worldwide average of sufferers of coeliac disease has been predicted to increase by a factor of ten over the next few years, resulting in a growing market for gluten-free products. The replacement of gluten, particularly in a bread formulation, presents a major technological challenge, as it is an essential structure-building protein, which is necessary for formulating high quality breads. Preliminary research at The National Food Centre involved the study of a number of commercially available gluten-free breads. These were found to be of lower quality than their gluten-containing counterparts. Current research has, therefore, embraced the use of novel ingredients to improve the quality and sensory attributes of gluten-free yeast bread formulations, and to study their effects on dough/batter rheology and baking characteristics. Seven dairy powders (6.5-90% protein) were incorporated into a wheat-starch based gluten-free bread formulation and their effects were studied over a period of time. Powders with higher protein contents produced breads with a less springy crumb (P<0.001), which resembled the crumb of wheat bread. A formulation based on rice and potato starch was supplemented with fish surimi (as a structure enhancer) at a 10% inclusion level (of starch weight). Three of the four surimis produced loaves with higher (P<0.001) volumes than the control, a softer (P<0.001) crust and crumb texture than the control, and were favourably received by a sensory panel. A central composite response surface design consisting of two predictor variables, Hydroxy Propyl Methyl-Cellulose (HPMC) [0.5-2.5% flour weight basis (fwb)] and water (70-95% fwb) was used to optimise a rice/potato starch based gluten-free formulation. Specific volume and loaf height increased as water addition increased (P<0.01). Crumb firmness decreased as water levels increased (P<0.01). The number of cells/cm2 increased as, Hydroxy Propyl Methyl-Cellulose and water increased (P<0.01). From the data obtained, optimal ingredient levels were determined. The optimised formulation contained 2.2%, Hydroxy Propyl Methyl-Cellulose and 79% water (fwb) and measured responses compared favourably to predicted values.

ABSTRACTThe formulation of gluten‐free (GF) bread of high quality presents a formidable challenge as it is the gluten fraction of flour that is responsible for an extensible dough with good gas‐holding properties and baked bread with good crumb structure. As the use of wheat starch in GF formulations remains a controversial issue, naturally GF ingredients were utilized in this study. Response surface methodology was used to optimize a GF bread formulation primarily based on rice flour, potato starch, and skim milk powder. Hydroxypropylmethylcellulose (HPMC) and water were the predictor variables. Analyses of the treatments from the design were made 24 hr after baking. Specific volume and loaf height increased as water addition increased (P < 0.01). Crumb firmness decreased as water levels increased (P < 0.01). Significant interactions (P < 0.01) between HPMC and water were found for the number of cells/cm2. The number of large cells (>4 mm2) decreased with increasing levels of HPMC and water. Optimal ingredient levels were determined from the data obtained. The optimized formulation contained 2.2% HPMC and 79% water flour/starch base (fsb) and measured responses compared favorably to predicted values. Shelf‐life analysis of the optimized formulation over seven days revealed that, as crumb firmness increased, crust firmness and crumb moisture decreased.

The effect of long- and short-term frozen storage prior to thawing, on the quality of freeze-chilled, commercially made lasagnes was examined as was the effect of modified atmosphere packaging (MAP). In the short-term trial, four process treatments were used; fresh, chilled, freeze-chilled and frozen. In the long-term trial, the lasagnes were frozen for 3, 6, 9 or 12 months, thawed and tested, or were thawed and then chilled at 4°C for 6 days (freeze-chilled). In the MAP trial, the lasagnes were subjected to either the freeze-chill treatment or freeze treatment, and before freezing were packed in either (i) air, (ii) 40% CO2/60% N2 or (iii) 40% CO2/30% N2/30% O2. In the short-term trial frozen and freeze-chilled lasagne had significantly higher drip loss than fresh or chilled before reheating, but this was not evident after heating. Similarly, freeze-chilled lasagne had a brighter colour (L/b) than chilled before heating, but again this was not evident after heating. No difference was found in firmness or sensory acceptability of lasagne from the different treatments. Freeze-chilled and frozen lasagne had higher total viable counts (TVC) than chilled or fresh. Packing in CO2/N2/O2 (40:30:30) led to a darker unheated lasagne than packing in CO2/N2 (40:60) or air, but this was not evident for heated lasagne. Packing in CO2/N2 (40:60) led to a firmer product than packing in air for the frozen lasagne but not for freeze-chilled lasagne. Atmosphere had no effect on TVC or drip loss values. Lasagnes stored frozen for 12 months were firmer than those stored for 3, 6, or 9 months. Storing frozen for 9 or 12 months also led to higher drip loss values than storing for 3 months for unheated lasagnes but when heated, the opposite effect was seen. Lasagnes stored for 3 months had the highest L/b (white/yellow ratio) values while those stored for 12 months had the lowest. Length of time in frozen storage had no influence on TVC values.

The replacement of gluten presents a major technological challenge, as it is an essential structure-building protein, which is necessary for formulating high quality cereal-based goods. Rising demands for gluten free products parallels the apparent or real increase in coeliac disease, or other allergic reactions/intolerances to gluten. This paper reviews the current prevalence of coeliac disease, and recent advances in the preparation of gluten-free products, using starches, hydrocolloids, gums and novel ingredients and processes.

Freeze-chilling of food involves freezing and frozen storage followed by thawing and chilled storage. In this study, the effect of freeze-chilling on the quality of cooked green beans and carrots was examined, as was the effect of long and short-term frozen storage prior to thawing. Three process treatments were used in the short-term trial; chill, freeze-chill and freeze and the products were tested for firmness, colour, centrifugal drip loss, total viable count (TVC) and taste panel acceptability. Results showed that freeze-chilling and freezing led to softer cooked carrots (P<0.001) than chilling. However, freeze-chilling and freezing had no effect on the texture of cooked green beans (P>0.05) but led to significantly higher drip losses than chilling (P<0.001). Freeze-chilling and chilling led to paler green beans but this was not reflected in the taste panel acceptability scores. No difference in TVC was found between any of the process treatments for cooked carrots or green beans. In general, frozen storage (−25 °C) for up to 12 months had no effect on firmness, drip loss, colour, total viable count or sensory acceptability of freeze-chilled cooked carrots and green beans compared to freezing.

As quotas and the supply of conventional species continue to tighten, there is a need to test the acceptability of many fish species. Seven fish species (albacore tuna, cardinal fish, orange roughy, blue ling, redfish, roundnose grenadier and Greenland halibut) were cooked by the sous vide process (Barriquand Steriflow retort; 20 min/90 °C) in 12 savoury sauces. Sensory results showed that sous-vide-cooked albacore tuna, cardinal fish and blue ling were the most acceptable species and tikka, tomato-and-pesto, arrabbiata and hollandaise the preferred sauces. Greenland halibut and roundnose grenadier were too soft after sous vide cooking. Freezing post sous vide cooking did not influence product quality and gave additional benefits over chilling of an extended shelf life and more flexibility in relation to product safety. The pH of the sauces was in the range 3.96 (cajun) to 5.42 (bearnaise) and mean pH values fell from 4.66 before sous vide cooking to 4.38 after cooking. Sauce colour also became lighter during sous vide cooking of fish portions, as indicated by Hunter Lab colour values. The results of the research have been disseminated to seafood companies and scale-up trials are in progress.

Freeze-chilling involves freezing and frozen storage followed by thawing and chilled storage. It offers logistic benefits for fish packers as it enables packaged fillets to be held frozen and then released into the chill chain as required. Trials with whiting, mackerel and salmon fillets/portions indicated no difference in odour scores (raw samples) between freeze-chilled and chilled samples; however, freeze-chilled salmon portions were inferior in terms of odour to chilled. Fresh fillets received the highest acceptability scores (cooked samples) followed by frozen, chilled and freeze-chilled samples. The pattern in the data was the same for each species and there was no statistically significant difference between the freeze-chilled and chilled samples. The total volatile base nitrogen (TVBN), trimethylamine (TMA) and total viable count (TVC) data were the same for the three species in that the chilled and freeze-chilled samples had the highest values and the fresh and frozen the lowest. However, there was no statistically significant difference between the freeze-chilled and chilled samples. Freeze-chilled samples had the highest free fatty acid (FFA) and peroxide values (PV) but the levels were low and did not influence sensory response. Gravity drip was significant in the frozen and freeze-chilled samples but presented no major visual problems and could readily be absorbed by drip pads. The effects of the four treatments on the colour and texture of the raw samples were small in practical terms.

Many commercially available gluten-free breads are inferior in quality to their gluten-containing counterparts. They also have a relatively short shelf life. The current study investigated the effects of 3% milk protein isolate and 3% novel rice starch addition to a gluten-free bread formulation, and on the intermediate (8 days) and long-term (43 days) staling profile of both gluten-free bread formulations, packed in an 80% CO2\20% N-2 atmosphere. Dairy protein and rice starch addition increased loaf volume and the loaves were preferred to a control sample by an untrained panel. The most notable changes in crumb hardness occurred in the early days of the testing periods for the control gluten-free bread in both the intermediate and long-term studies.