Effect of soaking,cooking and crude α-galactosidase treatment on the oligosaccharide content of red gram flour

The contents of sucrose, raffinose, stachyose, verbascose, total soluble sugars and reducing sugars in whole seeds of 14 cultivars of red gram (Cajanus cajan) grown in Karnataka state were determined. The effects of soaking, cooking and crude α-galactosidase treatment on the levels of the raffinose family of sugars were investigated. The percent losses of raffinose, stachyose and verbascose after soaking the red gram seeds for 16 h were 54.6, 55.4 and 33.3%, respectively. Cooking the red gram seeds for 60 min resulted in a decrease of 80.2% for raffinose, 87.2% for stachyose and 81.6% for verbascose. Thin-layer chromatographic analyses of 4 h enzyme-treated samples revealed complete hydrolysis of galactooligosaccharides. Therefore, α-galactosidase from Cassia sericea could have potential use in the food industry.     

Effect of frozen storage and freeze–thaw cycles on the rheological and baking properties of frozen doughs

The effects of prolonged frozen storage and repeated partial freeze–thaw cycles on the rheological and baking properties of nine commercial wheat cultivars were evaluated. The gluten strength of the cultivars ranged from medium to high, whereas the starch swelling characteristics were similar for most cultivars, except Parshall, which exhibited exceptionally high swelling properties. The doughs were subjected to frozen storage for 4–12 weeks, with and without freeze–thaw cycles. The enthalpy of freezable water was significantly affected by initial freezing, whereas, the rheological properties of the doughs were more susceptible to freeze–thaw cycles. After baking, all cultivars produced bread of acceptable quality, although cv. Parshall exhibited the highest crumb softness, irrespective of the frozen treatment. Results indicate that flours with high starch swelling characteristics, along with moderately high gluten strength, may be most ideal for producing optimum quality frozen doughs, with good shelf life and baking properties.     

Advantages of ohmic cooking in the kilohertz range – Part II: Impact on textural changes and approaches to improve heating uniformity

The impact of ohmic heating (OH) in the low (12 kHz) and high (300 kHz) kilohertz-range on textural changes and texture uniformity of potato cubes and whole potato tubers was investigated. Potatoes were heated in aqueous NaCl solution with a conductivity of 2.5 mS/cm. Texture was characterized by cutting and puncture tests and the energy (mJ) necessary to cut or penetrate the samples was found to be a suitable indicator. The impact of the initial temperature of the surrounding liquid on the heating uniformity was analyzed by starting the cooking treatment in cold (20 ± 2 °C) and in hot (90 ± 5 °C) NaCl solution. To further improve the heating efficiency, the conductivity was adjusted during the treatment. With an increasing power input during OH, increasing texture softening rates were observed. Compared to conventional cooking, an up to 8-times faster texture softening rate occurred. Treatments at 300 kHz resulted in a better texture uniformity compared to OH at 12 kHz. Compared to the conventional cooking, OH treatments resulted in significant (p ≤ 0.05) higher weight losses and a higher texture softening at similar cooking degrees. By adjustment of the liquid conductivity and power input during the treatment, textural properties were improved, and weight loss could be reduced.Industrial relevanceOhmic heating (OH) is an alternative heating technology with the potential to reduce processing times and energy consumption. It can overcome limitations in the heat transfer particularly given for large-volume solid foods and provide a uniform heating. However, limited attention has been given to the effects of the product and process parameters on the heating uniformity during OH treatments of solid foods. The present paper highlights the importance of the electrical conductivity and the frequency of the applied electric field on the texture uniformity. The obtained results contribute to the understanding of the interaction of the electric field and the food matrix, which is the basis for the implementation of tailored and targeted processing concepts in the industry.     

Effects of cooking methods on the β-carotene levels of selected plant food materials

In the present study, the β-carotene contents of 14 plant food materials prepared by boiling, steaming, or baking or when they are raw were analyzed and compared. After boiling three pulse species, namely, peas, kidney beans, and dried mung beans, β-carotene contents of peas and kidney beans increased significantly, whereas that of mung beans (dried material) decreased. True retention factors of β-carotene contents in the cooked kidney beans, peas, and mung beans after boiling were 174.2, 128.3, and 91.8%, respectively. After steaming, the β-carotene content of regular millets significantly decreased but that of taros increased, in which the true retention factors were observed with β-carotene contents of 72.4% in the steamed regular millets and 160.9% in the steamed taros. Moreover, β-carotene contents in yellow-fleshed sweet potato (raw: 896.2 μg/100 g) decreased by baking (786.4 μg/100 g) and steaming (steaming: 553.1 μg/100 g). These results suggest that β-carotene contents in the selected plant food materials markedly depend on the cooking method and plant food materials classification.     

Effect of water content,temperature and storage on the glass transition,moisture sorption characteristics and stickiness of β‐casein 1

Moisture sorption isotherms at +4 °C and +22.5 °C were obtained for β‐casein after isolation and after 9 months of storage at ‐29 °C and +22.5 °C. Glass transition state diagrams (T_g vs. moisture) were determined for β‐casein after storage. The results showed that effects of storage temperature on moisture sorption isotherms were varied; however, at any a_w differences in moisture content were small (< 0.03g H₂O/g solids at high a_w). β‐casein stored at ‐29°C had lower m_o and T_g values than that of β‐casein stored at +22.5°C. The glass transition temperatures for β‐casein were above room temperature, even at a_w = 0.76. Onset of stickiness occurred above a_w = 0.76.     

Microbial quality, and effect of cooking on survival of Salmonella, in Kokariç

A special preparation from the small intestine of lamb, called kokariç, is widely consumed in Turkey. In this study, Salmonella was not isolated from raw kokariç. Conventional ways of cooking, except precooking, destroyed Salmonella in artificially contaminated kokariç. The microbial quality of cooked kokariç bought from street sellers was not safe for public health consumption because of environmental contamination.     

Jam processing and storage effects on β-carotene and flavonoids content in grapefruit

Grapefruit phytochemicals (β-carotene and flavonoids) stability after different jam processing was evaluated. Osmotic dehydration, microwave energy and conventional heating techniques have been used to obtain jam. β-Carotene and individual flavonoids were analyzed by HPLC technique. The results showed that jam obtained from osmodehydrated fruit (ODJ) is the only that preserved completely the β-carotene content. All processes of production of jam significantly decreased the content of narirutin (NAT), poncirin (PON), naringenin (NAG) and quercetin (QUER), while naringin (NAR) remained stable. Jams obtained by applying a heat treatment showed significant lower values of NAG and QUER in comparison with ODJ. The jam obtained from osmodehydrated fruit, without being submitted to any heat treatment, showed at the end of storage the highest contents of naringin, hesperidin, neohesperidin, didymin, quercetin, poncirin and the total sum of analysed flavonoids. In general, the phytochemical loss in jams as a consequence of processing was lower than those provoked by storage effect.     

Effect of starter culture and storage temperature on the content of biogenic amines in dry fermented sausage poličan

Water activity, pH, microbial counts (total counts/TCM/, coliforms, Enterobacter, Proteus, Pseudomonas, Escherichia and Lactobacillus spp., respectively), and seven biogenic amines (BA) were determined in dry fermented sausage 'poli?an' produced using starter culture A (Lactobacillus sakei, Staphylococcus carnosus, S. xylosus) or B (L. sakei, S. carnosus, Pediococcus pentosaceus), ripened 42 days, and subsequently stored at 8 or 22°C 60 days. Counts of lactobacilli were higher and TCM lower in the A-sausage when ripening was finished. Tyramine (quantitatively most important BA) content was not different (P>0.05) in A- (90 mg/kg of dry matter, DM) or B-sausage (91 mg/kg DM) at the end of ripening. The effect of the storage temperature on BA content was not significant (P>0.05) in the case of either tyramine or any other tested BA. The increase of total BA content during ripening was not different (P>0.05) between A- and B-sausages (final value 190 and 222 mg/kg DM, respectively). However, sum of BA was significantly higher (P<0.05) in B-sausage as compared with A-sausage at the end of either refrigerated storage (304 and 236 mg/kg DM) or room temperature storage (468 and 206 mg/kg DM, respectively). It is concluded that legislative limits should be established for tyramine and total BA content in dry fermented meat products.     

Impact of γ-irradiation,CIPC treatment,and storage conditions on physicochemical and nutritional properties of potato starches

In the present study, three potato varieties were treated with chlorpropham (CIPC, 35 ppm), γ-irradiated (0.1 kGy) and stored for up to 5 months at 8 °C, and the physicochemical properties and in vitro starch digestibility of native and cooked starches were investigated. Sprouting was found to be satisfactorily suppressed by γ-irradiation and CIPC treatment. However, irradiation increased total free glucose content in two potato varieties, and decreased the thermal transition and pasting temperature of starch. The crystallinity of starch in irradiated potatoes decreased significantly (p ? 0.05) which may explain its decreased resistant starch content. Sprout inhibiting treatments and storage had no effect on in vitro starch digestibility in cooked starches, but cooling cooked starch significantly (p ? 0.05) increased its resistant starch content.     

Effects of marination, cooking and storage on physico-chemical and microbiological properties of ready to eat trout döner kebab

The aim of this work was to investigate the use of rainbow trout (Oncorhynchus mykiss) in ready to eat döner kebab production and determine the effects of marination, cooking and storage conditions (4 and ?18 °C) on physico-chemical and microbiological properties of döner kebab. The raw trout meat, raw, cooked and stored döner kebab samples were subjected to moisture, protein, fat, ash, color, pH, cholesterol, biogenic amines, lipid oxidation, fatty acids profile, texture, microbiological and sensory analysis. The results indicated that the major fatty acids in trout döner kebab were palmitic, stearic, oleic, omega-3 and omega-6 fatty acids and unsaturated fatty acids were higher than saturated fatty acids (p < 0.05). Low biogenic amine and cholesterol contents were determined in döner kebab. It was found that ?18 °C of storage temperature was more effective than 4 °C for inhibition of lipid oxidation and microbial growth in trout döner kebab (p < 0.05). While cooking affected parameters evaluated (p < 0.05), marination did not have any significant effect. The study results indicated that using rainbow trout meat in döner kebab production could be beneficial to provide healthy meat products without posing any acceptability problems in terms of quality factors. This is the first paper to be reported on physico-chemical and microbiological properties of döner kebab produced with rainbow trout and effects of marination, cooking and different storage temperatures on these physico-chemical and microbiological properties.     

Study of the functionality of selected hydrocolloids and their blends with κ-carrageenan on storage quality of vanilla ice cream

In the present paper, the functionality of hydrocolloids related to the rheological, physical and sensory characteristics of ice cream mixes and frozen ice cream was studied. Carboxylmethylcellulose, guar gum, sodium alginate and xanthan gum were used as primary stabilizing agents, whereas κ-carrageenan as secondary. The hydrocolloid concentrations were 0.1 and 0.2% and the primary to secondary ratio was 9:1. The ice cream samples were stored under quiescent frozen conditions. Samples were taken after 4, 8 and 16 weeks of storage and examined for the functionality of the stabilizing systems.The addition of hydrocolloids significantly reinforced the shear thinning behavior, particularly in the case of sodium alginate, xanthan gum, and κ-carrageenan which was attributed to gelation phenomena. Sodium alginate attained the better stabilizing effect improving textural quality and acceptance of ice creams even after 16 weeks of storage, whereas the presence of κ-carrageenan found to be a crucial factor for the cryoprotection. Xanthan gum was also evaluated as an effective stabilizing agent, indicating that gelling hydrocolloids may remarkably amend ice cream shelf life.Moreover, principal components and cluster analysis of instrumental and sensory data furnished important information for the correlation of objective and sensory properties and discrimination of stabilizing systems based on quality criteria.     

Effects of flavorings, storage conditions, and storage time on survival of Staphylococcus aureus in Sürk cheese

The objectives of this study were to determine the cumulative effects of flavorings (chili pepper, thyme, mint, cumin, nutmeg, allspice, clove, cinnamon, black pepper, salt, and hot red pepper paste), storage conditions, and storage time on the survival of Staphylococcus aureus in Sürk cheese and to monitor the associated chemical changes. Sürk cheese, a traditional Turkish cheese, was produced by heating diluted nonfat yogurt and adding flavorings to the resultant acid-heat curd. The cheese was later inoculated with S. aureus, shaped conically, and stored aerobically for mold growth and anaerobically in olive oil for 30 days at room temperature. The moisture content of aerobically stored cheese decreased over time and led to increases in total solids, salt, salt-in-moisture, and ash content during ripening (P < 0.05). The presence or absence of the flavorings had no significant effect, whereas storage conditions and storage duration decreased the survival of S. aureus (P < 0.05).     

Impact of β-glucan on debittering,bioaccessibility and storage stability of skim milk fortified with shrimp oil nanoliposomes

Shrimp oil was encapsulated in nanoliposomes and fortified into skim milk. Shrimp oil nanoliposomes (SONL) were thermodynamically stable when added into skim milk at 10 mL 100 mL⁻¹. Mild bitterness in fortified skim milk caused by the SONL was masked by adding β-glucan at various levels (0.05–0.2 g 100 mL⁻¹). With the addition of SONL, fortified skim milk appeared more reddish in colour due to the presence of astaxanthin. Addition of β-glucan resulted in the increase in viscosity of the fortified milk by forming network of junction zones. During the storage of skim milk fortified with SONL and 0.1 g 100 mL⁻¹ β-glucan at 4 °C for 15 days, no major quality changes took place. Simulated in vitro digestion studies revealed that 45.41 g 100 g⁻¹ eicosapentaenoic acid (EPA) and 48.86 g 100 g⁻¹ docosahexaenoic acid (DHA) from shrimp oil were bioaccessible for absorption in the gut after digestion.     

The effect of dietary supplementation of vitamins C and E on the α-tocopherol content of muscles, liver and kidney, on the stability of lipids, and on certain meat quality parameters of the longissimus dorsi of rabbits

The trial was carried out to investigate the effects of adding to the diet of rabbits vitamin E (40; 300; 500 ppm) and C (0; 500 ppm), on vitamin E deposition in the muscles and organs, on the oxidative stability of muscular lipids, and on various meat quality characteristics. The α-tocopherol content in muscles and organs was roughly doubled by feeding the highest levels of vitamin E; it was also increased by giving 500 ppm of vitamin C, but only in those muscles of rabbits receiving 40 ppm of vitamin E. The α-tocopherol content in tissues was negatively correlated with TBARS values of the longissimus dorsi (LD) at days 6 and 8 post mortem (p.m.). Five hundred parts per million (ppm) of vitamin C increased lipid stability of the LD at both 6 and 8 days p.m., though its effect was significant only with 40 ppm of vitamin E. Moreover, 500 ppm of vitamin C resulted in the lowest L(*) and highest pH values at all p.m. times, when the dietary vitamin E was equal to 40 ppm, and in the highest L(*) and lowest pH values when the vitamin E was equal to 300 ppm. Conversely, weight losses of the LD were the lowest, at days 6 and 8 p.m., in the group fed the highest levels of both vitamins.     

Impact of coffee preparation on total phenolic content in brewed coffee extracts and their contribution to the body’s antioxidant status

Food Science and Biotechnology - Although coffee has been reported as a major contributor to antioxidants in the diet, there are limited studies assessing how brewing methods and types of coffee...     

Impact of high pressure processing on total antioxidant activity,phenolic, ascorbic acid,anthocyanin content and colour of strawberry and blackberry purées

The present study was undertaken to assess the effect of high pressure treatments and conventional thermal processing on antioxidant activity, levels of key antioxidant groups (polyphenols, ascorbic acid and anthocyanins) and the colour of strawberry and blackberry purées. Bioactive compounds (cyanidin-3-glycoside, pelargonidin-3-glucoside, ascorbic acid) and antioxidant activity were measured in strawberry and blackberry purées subjected to high pressure treatment (400, 500, 600 MPa/15 min/10–30 °C) and thermal treatments (70 °C/2 min). Samples were assessed immediately after processing. Different pressure treatments did not cause any significant change in ascorbic acid (p > 0.05). In contrast, following thermal processing (P₇₀ ≥ 2 min) ascorbic acid degradation was 21% (p < 0.05) as compared to unprocessed purée. However, no significant changes in anthocyanins were observed between pressure treated and unprocessed purées (p > 0.05), whereas conventional thermal treatments significantly reduced the levels (p < 0.05). In general, antioxidant activities of pressure treated strawberry and blackberry purées were significantly higher (p < 0.05) than in thermally processed samples. Colour changes were minor (ΔE) for pressurised purées but the differences were slightly higher for thermally treated samples. Redness of purées was well retained in high pressure treated samples. Therefore processing strawberry and blackberry by high pressure processing could be an efficient method to preserve these products quality. Hence high pressure processing (HPP) at moderate temperatures may be appropriate to produce nutritious and fresh like purées.Industrial relevanceThis research paper provides scientific evidence of the potential benefits of high pressure processing in comparison to thermal treatments in retaining important bioactive compounds. Antioxidant activity (ARP), ascorbic acid, and anthocyanins after exposure to high pressure treatments (400–600 MPa) were well retained. Our results also show that redness and colour intensity of strawberry and blackberry purées were better preserved by high pressure processing than conventional thermal treatment. From a nutritional perspective, high pressure processing is an attractive food preservation technology and offers opportunities for horticultural and food processing industries to meet the growing demand from consumers for healthier food products. Therefore high pressure processed foods could be sold at a premium than their thermally processed counterparts as they will have retained their fresh-like properties.     

Interaction of phosphatidylcholine and α-tocopherol on the oxidation of sunflower oil and content changes of phosphatidylcholine and tocopherol in the emulsion under singlet oxygen

Abstract: Interaction of phosphatidylcholine (PC) and α‐tocopherol (α‐Toc) on the oxidation of oil in the emulsion consisting of sunflower oil and water under singlet oxygen at 25 °C was studied by determining peroxide value (PV) and conjugated dienoic acid (CDA) contents. Singlet oxygen was produced by chlorophyll b under 1700 lux. Single addition of PC or α‐Toc decreased the values of peroxides and CDAs of oil in the emulsion via singlet oxygen quenching. PC and α‐Toc showed simply additive interaction in decreasing the singlet oxygen oxidation of oil in the emulsion. α‐Toc was a physical quencher of singlet oxygen in the emulsion, but PC involved chemical quenching in the antioxidant action. Chlorophyll and PC contents were decreased in the emulsion under singlet oxygen, while α‐Toc was not. α‐Toc protected chlorophyll and PC from degradation, and was a more important component than PC in the oil oxidation under singlet oxygen in the emulsion.