Radiation Processing of Minimally Processed Carrot (Daucus carota) and Cucumber (Cucumis sativus) to Ensure Safety: Effect on Nutritional and Sensory Quality

ABSTRACT: In the present study, radiation processing of minimally processed carrot and cucumber at a dose of 2 kGy was carried out. The effect of this treatment on different quality parameters such as vitamin C content, total carotenoids content, sensory quality, texture, and color was determined over a storage period of 16 d at 8°C to 10° C. In the case of cucumber, treatment of irradiation as well as storage period showed no significant change in the total vitamin C content of either the control or the irradiated samples. In the case of carrots, a 2-kGy dose had no significant effect ( P < 0.05) on total vitamin C content of the samples. However, during storage, both control as well as irradiated samples showed significant decrease ( P < 0.05) in vitamin C content. Total carotenoids content in carrot remained almost unchanged after irradiation as well as during storage. Sensory evaluation results showed that irradiation had no significant ( P < 0.05) effect on the ratings of any of the sensory attributes in carrot. Radiation processing of cucumber affected the flavor significantly. However, this change did not alter the overall acceptability of cucumber. Textural studies revealed that in both carrot and cucumber, there was no significant change ( P < 0.05) in firmness of the central region after irradiation, whereas the peripheral region in carrot showed significant reduction in firmness. In the case of cucumber, there was no significant change ( P < 0.05) in the texture of both peripheral regions. However, during storage, the peripheral regions of carrot and cucumber showed significant increase in firmness. Color measurement results indicated no drastic change in color coordinates of carrot samples. Thus, the nutritional as well as sensory quality of minimally processed foods did not alter significantly after gamma irradiation.     

Effect of UV-B light and different cutting styles on antioxidant enhancement of commercial fresh-cut carrot products

Wounding stresses resulting from fresh-cut processing are known to enhance the antioxidant capacity (AC) of carrots by increasing the synthesis of phenolic compounds. Ultraviolet-B (UV-B) light exposure further promotes the formation of phenolic compounds. Changes in total soluble phenolics (TSP), 5-O-caffeoylquinic acid (5-CQA), total carotenoids, AC, and phenylalanine ammonia-lyase (PAL) activity of five commercial fresh-cut carrot products (baby carrots, carrot stixx, shredded carrots, crinkle cut coins, and oblong chips) were evaluated after exposure to UV-B dosage at 141.4 mJ/cm². Significant increases in TSP, AC and 5-CQA levels were observed for each sample following UV-B exposure. Increases in PAL activity were also observed in all carrot products, except crinkle cut coins. Total carotenoids of the carrot products were unchanged by UV-B exposure. Increases in AC levels corresponded directly with increases in the area/weight ratio (exposure area) of the fresh-cut carrot products.     

Occurrence of pathogens in raw and ready-to-eat meat and poultry products collected from the retail marketplace in Edmonton, Alberta, Canada

A total of 800 meat and poultry products were purchased from the retail marketplace in Edmonton, Alberta, Canada. The products consisted of raw ground beef, chicken legs, pork chops, and ready-to-eat fermented sausage, roast beef, processed turkey breast, chicken wieners, and beef wieners. The samples were analyzed to determine the prevalence of Shiga toxin-producing Escherichia coli, Salmonella, Campylobacter spp., and Listeria monocytogenes. Shiga toxin-producing E. coli 022: H8 was found in one raw ground beef sample. Salmonella and Campylobacter were found in 30 and 62% of raw chicken legs, respectively. L. monocytogenes was found in 52% of raw ground beef, 34% of raw chicken legs, 24% of raw pork chops, 4% of fermented sausages, 3% of processed turkey breast, 5% of beef wieners, and 3% of chicken wieners. The occurrence of pathogens in this study is similar to that in retail products in many other international locales.     

Free radical generation in uncooked carrot (Daucus carota) root tissue after cell disruption – A model for chemical reactions during mastication

Free radical processes resulting from cell disruption of carrot hypocotyl root stock have been investigated at various developmental stages and positions using EPR spectroscopy in combination with chemical spin traps, in order to simulate reactions that might occur in the mastication process when eating raw carrot tissue. With the spin trap PBN, EPR spectra corresponded to a carbon-centred radical adduct of the spin trap and the N-(t-butyl)aminoxyl radical, an oxidative breakdown product of the spin trap. When 4-POBN was used, an oxidation product of the spin trap was observed along with the N-(t-butyl)aminoxyl radical. These oxidation reactions were strongest in the root tips. Additional measurements with spin traps DEPMPO and DPPMPO showed the formation of hydroxyl radical adducts. Thus oxidative free radical production occurs on cell disruption, especially in rapidly developing tissue, a result which suggests that free radicals might not be detrimental components of foods.     

Aeration of model gels: Rheological characteristics of gellan and agar gels

Model food sols containing gellan and agar at different solid concentrations were aerated. The rheological characteristics of the setted gels were determined. These were the compression characteristics (fracture strain/stress/energy, firmness and the total energy for compression) and the stress relaxation characteristics (extent of relaxation and relaxation time). Fracture strain of gels increased due to aeration indicating that the aerated samples exhibited a delayed fracture due to the presence of incorporated air. The extent of increase in fracture strain for aerated agar gels over the corresponding non-aerated samples is 1.7-23.1% while it is 4.3-15.1% for gellan gels. The extent of relaxation increased due to aeration while relaxation time (λ) decreased. Relaxation time for aerated agar and gellan gels is 9.6-40.7% and 19.6-37.6% lower than the non-aerated samples. At a low concentration of hydrocolloid, the effect of aeration was usually non-significant (at p ? 0.05) while prominent changes in rheological behaviour occurred at a high concentration. Aeration of food gels offered the possibility of rheological modifications to suit the consumer requirements in developing specialty fabricated gels.     

Meat cut and injection level affects the tenderness and cook yield of processed roast beef

The effect of muscle cut used and brine injection level on the processing characteristics of small pre-cooked roast beef was determined. Meat cuts (inside, outside, eye of round, knuckle, clod, chuck roll and brisket) were cut into small roasts (750 g) and injected at three levels (110, 125 and 150% over raw roast weight) with a non-injected control. Muscle cuts from the chuck can be used to successfully manufacture cooked mini roast beef. However, the use of small roasts resulted in cook yields that are considerably less than what was expected with large intact muscle roasts. Some variation in tenderness between the muscles was seen, but when muscles were injected there was a significant increase in tenderness and a reduction in the variability in tenderness within the muscle. Roasts injected to 125% above green weight resulted in the highest cook yields.     

Salmonella spp. contamination in fresh pork and chicken sausages marketed in Niterói and Rio de Janeiro,Brazil

Fresh sausages are one of the most popular meat products consumed in Brazil. However, the use of contaminated raw material, unhygienic handling during processing, and inadequate storage could be hazardous to consumer’s health, since fresh-sausage processing does not include heat treatment and the product may carry several human pathogens such as Salmonella spp.. In this study, a total of 80 fresh sausages prepared with pork and chicken meat were evaluated regarding Salmonella spp. presence by PCR after selective enrichment and bacteriological culture. Twenty-one sausage samples (27 %) proved to be contaminated with Salmonella spp.. Sixteen (76 %) contaminated samples were detected by PCR combined with enrichment broth culturing, whereas conventional microbiological screening detected only 8 (38 %). In this study, evidence was raised regarding packing conditions of fresh sausages, since it seems that there is no significant difference in Salmonella spp. contamination among samples in their original packing (23 %), wrapped in plastic or unpacked (27 %). Similarly, meat composition seems not to have a determinant influence in contamination, since 20 % of the chicken and 29 % of the pork sausages were contaminated. The contamination rate of Tuscan-type sausages was 37 %, while contamination was found in 21 % of ham sausages, suggesting that the cut of pork did not have a determinant influence in the contamination by Salmonella in fresh sausages. The results shown here indicate that fresh sausages marketed in Niterói and Rio de Janeiro may be contaminated with Salmonella spp., requiring more attention by sanitary authorities in order to assure the safety of this food.     

Raman analysis of surimi gelation by addition of wheat dietary fibre

Raman analysis has been carried out to study the effects of Vitacel^® wheat dietary fibre (WDF) during gelation of surimi. The main results reveal the following: (a) Vitacel^® comprises natural cellulose I as major component; (b) hydration of WDF leads to νCH frequency upshifting and decreasing intensity. On the basis of these spectral features it is suggested that water transfer from protein to WDF can occur in surimi gels. WDF hydration can be interpreted in the sense that this fibre either takes water that is delivered from the gel protein upon heat-mediated formation of β-sheets and hydrophobic contacts and/or or acts as an active dehydrating agent. An increase of solvent-exposed hydrophobic side chains is observed in the sol phase, upon the addition of WDF, which may cause breaking of intermolecular protein hydrophobic contacts; a subsequent change upon WDF-containing gel formation is the reduction in the νCH intensity, which may be indicative of increasing hydrophobic WDF-protein contacts. Interestingly, these results constitute molecular data, to be considered when designing restructured fish products with these fibre ingredients.     

DETERMINATION OF THE TOTAL LIPID CONTENT OF PORK RETAIL CUTS AT TWO EXTERNAL FAT TRIM LEVELS

Currently, retailers are required to conduct semi-annual or annual analyses of their labeled products under the USDA's Nutritional Labeling Verification procedures. The following study analyzed pork retail cuts that were trimmed to 0.0 cm or 0.64 cm external fat remaining. Lipid content was analyzed to determine the cuts that met "lean" (<10% total fat) and "extra-lean" (<5% total fat) specifications. The tenderloin, inside ham steak, and inside ham roast trimmed to 0.0 cm external fat remaining met the requirements for "extra-lean" labeling. The loin chop, loin roast, tip steak and tip roast trimmed to 0.0 cm external fat remaining, and the inside ham steak and inside ham roast trimmed to 0.64 cm external fat remaining, met the specifications for "lean" labeling.     

Low gamma irradiation of raw meat. II. Bacteriological effects on samples from butcheries

One hundred and twenty samples of raw ground meat, a component of ‘filet américain’ consumed raw in some European countries, were investigated, both directly and after gamma irradiation with a dose of 1 kGy. Moreover, the meat was checked serologically for presence of other type beside beef.Salmonella were isolated from 23 (19.2%) non-irradiated samples, MPN counts ranged from 40 to 2 × 10³ organisms/100 g. Only 1 sample was Salmonella-positive after irradiation, at an amount of 2.3 × 10²/100 g.Yersinia enterocolitica was found in 60 (50%) samples of raw meat but this organism was not isolated from irradiated samples.From none of the investigated samples of raw meat could Campylobacter jejuni be isolated.The average reduction after irradiation of the total aerobic count and Enterobacteriaceae was 2.18 and 4.00 log cycles, respectively.In 5 of 120 samples of raw ground meat intended for preparation of filet américain the presence of pork was demonstrated.Based on the results of this study it may be concluded that irradiation of raw meat with a dose of 1 kGy eliminated of reduced some pathogens of public health concern to acceptable levels.     

Release and absorption of carotenes from processed carrots (Daucus carota) using in vitro digestion coupled with a Caco-2 cell trans-well culture model

The release and absorption (bioavailability) of carotenoids is a prerequisite for their nutritional impact. This can be strongly affected by the processing conditions used to prepare the food matrix that contains them. To determine the effect of processing on carotenoid bioavailability, homogenized, raw, blanched and cooked carrots were exposed to an in vitro gastric and intestinal digestion model. Final digest samples were placed onto a Caco-2 cell trans-well monolayer culture to mimic intestinal absorption. The results show that the cooked carrot puree consisting of primarily single plant cell particles had the highest release of carotenes, followed by blanched consisting primarily of plant cell clusters and raw carrot puree consisting of larger plant cell clusters. Absorption through the Caco-2 cell layer was the highest from the digesta of cooked carrot puree followed by the digesta of blanched carrot puree. This study demonstrates that thermal processing and/or mechanical homogenization to disrupt plant cell wall matrix enhances the in vitro bioavailability of carotenes from carrots.     

Gelling properties of gelatin–xanthan gum systems with high levels of co-solutes

The effects of moisture content, xanthan gum (XG) addition and glucose syrup (GS):sucrose ratio on elastic (G′) and viscous (G″) moduli during in situ gelation and on large deformation rheological properties of cured gels were investigated. An increase in both moduli of the samples with XG addition indicates network structure being strengthened. All gel samples exhibited distinct fracture. An increase in GS:sucrose ratio led to a decrease in fracture stress and an increase in fracture strain, implying more flexible polymer network. Decreasing moisture content may lead to phase separation between sugar-rich and polymer-rich phases to form stronger connection within the network structure. Textural characteristics of samples analyzed using a texture map, indicated that increasing GS:sucrose ratio rendered the sample texture more rubbery when the samples contained XG. We also related factors affecting the gelling mechanisms in terms of T_g measured by different techniques including DMA and modulated DSC.     

Deformation and fracture of emulsion-filled gels: Effect of oil content and deformation speed

The large deformation properties of gelatine, κ-carrageenan and whey protein isolate (WPI) gels filled with bound and unbound oil droplets were studied as a function of compression speed. The rheological properties of the gel matrices controlled the compression speed-dependency of the gels containing oil droplets. Polymer gels (gelatine and κ-carrageenan gels) showed a predominantly elastic behaviour. Their Young's modulus was not affected by the compression speed. The increase of fracture stress and strain observed with increasing compression speed was related to friction between the structural elements of the gels and, for gelatine, to the unzipping of physical bonds. Particle gels (WPI gels) showed a more viscoelastic behavior. Their Young's modulus and fracture stress increased with compression speed. This was attributed to the viscous flow of the matrix and friction phenomena between structural elements of the gel. The effect of an increase in the oil volume fraction (φ) on the Young's modulus was for all gels according to the Van der Poel theory. In addition, oil droplets embedded in the gel matrix acted as stress concentration nuclei and increased friction. The relative impact of these two effects was related to the viscoelastic properties of the gels and to droplet–matrix interaction. For polymer gels and gels with bound droplets, stress concentration phenomena played a relatively larger role. For particle gels and gels with unbound droplets, friction phenomena were relatively more important, increasing the viscoelastic character of the gels. As a result, an increase in φ resulted in a decrease of both fracture stress and fracture strain for polymer gels and in an increase of the fracture stress and a decrease of fracture strain for particle gels.     

Evaluation of Microwave Cooking Procedures and Ovens for Devitalizing Trichinae in Pork Roasts

Pork roasts from pigs experimentally infected with Trichinella spiralis were cooked in five microwave ovens. Twenty-nine procedures, generally recommended by the oven manufacturers or pork interest groups, were used. Infective trichinae were present after cooking in 50 of 189 roasts. Factors affecting infectivity included procedure used, use or nonuse of post-cooking standing or temperature holding, weight of roast, and internal temperatures attained. Five visually well done roasts contained infective trichinae including one in which all five temperatures taken exceeded 76.7°C. One other infective roast, with a small red spot, also had all temperatures at or above the 76.7°C level. Recommendations are made to minimize the potential that trichinae may survive in microwaved-cooked pork.     

Storage of Shell Eggs Influences the Albumen Gelling Properties

Eggs from hens at 42 and 65 wk of age, respectively, were stored for time and temperature combinations of 0, 7, 10, and 14 d at 4, 12, 20, 28, and 37 °C in two experiments. The egg albumen was analysed for raw albumen quality parameters and dry matter content. Albumen gels prepared at either 85 °C or 90 °C were analysed for the textural properties corrected stress σ and Hencky strain ε at fracture point, σ_fandε_f , respectively, by uniaxial compression. The denaturation temperature, T_D, of ovalbumin in albumen samples was analysed by differential scanning calorimetry, DSC, and related to standards of N-ovalbumin and S-ovalbumin. Fresh egg albumen was characterised by the formation of gritty gels of poor water-holding capacity with lowσ_f and ε_fvalues. The stress and strain of gels at fracture were maximal after 14 d at 4 °C, and ε correlated significantly with ovalbumin T_Dfor gels prepared at 85 and 90 °C. The grouping of egg albumen samples with respect to the form of ovalbumin present (N-, intermediate, or S-) correlated with the egg mass loss during storage. Within the study, the storage temperature was more determining for the conversion of N-ovalbumin into S-ovalbumin than storage time.     

Antioxidant potential of curry (Murraya koenigii L.) and mint (Mentha spicata) leaf extracts and their effect on colour and oxidative stability of raw ground pork meat during refrigeration storage

The aim of this study was to investigate the antioxidant activity of different solvent extracts of curry and mint leaf and their effect on colour and oxidative stability of raw ground pork meat stored at 4 ± 1 °C. The results indicated that among the two individual leaf categories, the ethanol extract of curry leaf (EHEC) and the water extract of mint leaf (WEM) showed higher DPPH and ABTS⁺ activity. EHEC also exhibited the highest total phenolic contents while these were the lowest for WEM. WEM showed the highest superoxide anionic scavenging activity (%). The pork meat samples treated with EHEC and WEM showed a decrease in the Hunter L- and a-values and a increase in b-value during storage at 4 °C. However, the pH and TBARS values were higher in control samples irrespective of storage periods. In conclusion, EHEC and WEM have the potential to be used as natural antioxidants to minimise lipid oxidation of pork products.     

Method for the static headspace analysis of carrot volatiles

A static headspace analysis/gas chromatography/mass spectrometry (SHA/GC/MS) method was developed to analyse the volatile composition of raw (seven different varieties), stored and cooked carrot samples. A total of 35 different volatile compounds were identified in carrots. Of these, trans-ocimene, 2,5-dimethyl styrene, camphor, borneol, α-santalene, α-selinene, γ-elemene and α-zingiberene in raw carrots and propanol in stored carrots were identified for the first time. Major volatile compounds identified in raw carrots were α-pinene, sabinene, myrcene, limonene, γ-terpinene, terpinolene, β-caryophyllene and γ-bisabolene. Mono-and sesquiterpenes accounted for about 97% of the total volatiles identified. Sizeable varietal differences (p<0.01) were observed. Carrot volatiles did not change appreciably during the 28 day storage period at 5, 25 and 35°C, except propanol that showed exponential increases at higher temperatures. No propanol was detected in fresh raw carrots. Cooking resulted in 88.6, 93.0 and 95.5% loss in total volatiles after cooking times of 10, 20 and 30 min, respectively.     

Formation and identification of nitrosylmyoglobin by Staphylococcus xylosus in raw meat batters: A potential solution for nitrite substitution in meat products

Staphylococcus xylosus and Pediococcus pentosaceus isolated from Chinese dried sausage were assessed for their ability to convert metmyoglobin into nitrosylmyoglobin in Mann–Rogosa–Sharp broth model systems and raw pork meat batters without the addition of nitrite. The results showed that samples in model systems with S. xylosus cultures had an absorption spectra that is typical of nitrosylmyoglobin, an obvious pink colour (judged by visual inspection) and a significantly higher a*-value than the control samples or samples inoculated with P. pentosaceus. In raw meat batters, the a*-values of the S. xylosus samples were almost the same as those for the meat with nitrite added. The complementary analysis of meat batter samples by photochemical information from UV–vis, electron spin resonance and resonance Raman spectroscopy revealed that the existing status of the myoglobin in meat batters inoculated with S. xylosus was mainly pentacoordinate nitrosylmyoglobin. This study provides a potential solution for nitrite substitute in meat products.