Rapid Determination of Total and Solid Fat Contents in Chocolate Products by Pulsed Nuclear Magnetic Resonance

A rapid pulsed NMR method of fat analysis in chocolate without prior solvent extraction was developed. Total fat content of 43 chocolate products was determined at 60°C using sucrose-oil mixtures as standards. Solid fat content (SFC) was calculated from the liquid oil content at different temperatures. Total fat content agreed to 0.90% standard error of prediction as compared with the Soxhlet method. SFC as determined by NMR correlated well with the dilatometry (r = 0.98) and the DSC (r = 0.96) results. This technique is suitable for quality control of chocolate and other lowmoisture, high-fat products.     

Effect of fermentation on in vitro digestibilities and the level of antinutrients in moth bean [Vigna aconitifolia (Jacq.) Marechal]

The effect of fermentation with varying temperatures and time periods on the nutritive value of Moth bean was studied. Results indicated that at 30 °C, protein digestibility increased from 60% in the non‐processed moth bean to 77%, 78% and 80% and at 35 °C, increased to 81%, 83% and 85% following 12, 18 and 24 h of fermentation (controlled) period, respectively. Fermentation also caused an appreciable enhancement (96–133%) in starch digestibility with increase in period and temperature of fermentation. Fermentation of moth bean resulted in 24–34% reduction in phytic acid content at 30 °C and 33–42.5% at 35 °C. Polyphenol content was reduced by 42%, 48% and 51% at 30 °C and by 44%, 49% and 54% at 35 °C after 12, 18 and 24 h of fermentation period, respectively. Prolonging the period of fermentation from 12 to 18 and 24 h at 30 °C also caused a loss in TIA.     

Maillard Reaction Products as Encapsulants for Fish Oil Powders

The use of Maillard reaction products for encapsulation of fish oil was investigated. Fish oil was emulsified with heated aqueous mixtures comprising a protein source (Na caseinate, whey protein isolate, soy protein isolate, or skim milk powder) and carbohydrates (glucose, dried glucose syrup, oligosaccharide) and spray‐dried for the production of 50% oil powders. The extent of the Maillard reaction was monitored using L*, a*, b* values and absorbance at 465 nm. Encapsulation efficiency was gauged by measurement of solvent‐extractable fat and the oxidative stability of the fish oil powder, which was determined by assessment of headspace propanal after storage of powders at 35 °C for 4 wk. Increasing the heat treatment (60 °C to 100 °C for 30 to 90 min) of sodium caseinate‐glucose‐glucose syrup mixtures increased Maillard browning but did not change their encapsulation efficiency. The encapsulation efficiency of all heated sodium caseinate‐glucose‐glucose syrup mixtures was high, as indicated by the low solvent‐extractable fat in powder (<2% powder, w/w). However, increasing the severity of the heat treatment of the sodium caseinate‐glucose‐glucose syrup mixtures reduced the susceptibility of the fish oil powder to oxidation. The increased protection afforded to fish oil in powders by increasing the temperature‐time treatment of protein‐carbohydrate mixtures before emulsification and drying was observed irrespective of the protein (sodium caseinate, whey protein isolate, soy protein isolate, or skim milk powder) and carbohydrate (glucose, glucose/dried glucose syrup, or oligosaccharide/dried glucose syrup) sources used in the formulation. Maillard reaction products produced by heat treatment of aqueous protein‐carbohydrate mixtures were effective for protecting microencapsulated fish oil and other oils (evening primrose oil, milk fat) from oxidation.     

Isopropyl N-(3-chlorophenyl) Carbarmate (CIPC) Effect on Nitrogenous Constituents of Potatoes

Potatoes treated with 1% or 3% CIPC and stored 16 weeks at 5°C and 20°C were analyzed for nitrogenous constituents. Treatment with 1% CIPC significantly (p < 0.025) increased total nitrogen and protein content in tubers of two cultivars compared to untreated control tubers following storage at 5°C and 20°C. Treatment with 3% CIPC increased total nitrogen and decreased protein in tubers stored at 20°C (p < 0.025), but decreased total nitrogen and protein in tubers stored at 5°C. Treating potatoes with CIPC prevented sprouting in both varieties and apparently caused the tuber to retain nitrogen.     

The influence of temperature and humidity on the life-cycle of Ectomyelois ceratoniae (Zeller) (Lepidoptera: Phycitidae)

Adults of Ectomyelois ceratoniae would not mate in small containers kept in constant conditions. Mating occurred and fertile eggs were laid when the adults were placed in a large conical cage, kept in regularly fluctuating conditions of light, temperature and humidity resembling their native habitat. The dusk/dawn light intensity changes were particularly important. Most mating and oviposition occurred from dusk until the following dawn, with adults motionless during daylight.At 70% r.h. eggs hatched on average in 4·2 days at 25°C, 3·0 days at 30°C and 3·6 days at 35°C. At 30°C, this period varied from 3·4 days at 30% r.h. to 3·0 days at 90% r.h. On a diet of soybean meal, sucrose and water at 30°C, the larval period averaged 30 days at 30% r.h., 13 days longer than at 70% r.h., and the low relative humidity also increased larval mortality. At 90% r.h., no larvae emerged from food that became very mouldy. The total developmental period from egg hatch to adult emergence at 70% r.h. averaged 48 days at 20°C, 30 days at 25°C and 23 days at 30°C.     

Extrusion for Producing Low-fat Pork and its Use in Sausage as Affected by Soy Protein Isolate

Low-fat pork was produced at extrusion temperatures (ET) of 25, 32.2,43.3,54.4, or 65.6°C with addition of soy protein isolate (SPI) at 0,1.5, or 3% and evaluated by measuring chemical and physical properties of low-fat pork sausage links. ET and SPI addition influenced moisture retention and fat reduction. The highest ET(65.5°C) gave the highest fat reduction in extrudates. TBARS decreased as ET and SPI increased. Extrudates at higher ET made darker and redder sausages. The hardness value of the control was not different from that of sausages from 65.6°C ET extrudates. The fat-reduced sausages were more springy and cohesive than the control. Depending on fat reduction, twin-screw extrusion influenced sausage color, texture, and lipid oxidation. The sausage links from 65.6°C ET extrudates with 1.5% SPI had the lowest fat, lowest TBARS, least cooking loss and were not different in hardness from control high-fat sausages.     

HIGH TEMPERATURE DRYING CHARACTERISTICS AND MOISTURE ADSORPTION ISOTHERMS OF BLACK PLUM (VITEX DONIANA) SYRUP AND SYRUP-STARCH

Modified sweeteners were formulated from mixtures of Black plum syrup and phosphorylated corn starch concentrations of 20, 30, and 40% (w/w). Each mixture was coated on an aluminium plate at 1 mm thickness, dehydrated at 60°, 70°, 80° and 90°C, and evaluated for drying and moisture sorption characteristics. Results showed that the mixtures exhibited falling rate drying characteristics. The rate of dehydration increased in the order 20% > 30% > 40% starch at constant temperature. The incremental choice of 10% starch and drying temperature except at 70° and 80°C had significant effect (p < 0.05) on drying rate. The moisture isotherm curves of the pre-dried mixtures were sigmoid in shape. Their monolayer values or upper critical moisture contents necessary for shelf-stability were significantly different from each other for the samples pre-dried at 60°C. The effect of drying temperatures on equilibrium moisture content was only significant at 90°C (p < 0.05).     

Characteristics and Functionality Enhancement by Glycosylation of Bitter Melon (Momordica charantia) Seed Protein

Seeds of ripe bitter melon (Momordica charantia) contain approximately 30% protein. However, this protein, which is less functional than soy protein, may have desirable functionalities as a food ingredient after modification. Bitter melon seed protein isolate (BMSPI) was prepared under optimal extraction conditions (defatted meal to 1.3 M NaCl was 1:10 w/v; pH 9.0) and its functional properties were investigated before and after modification by glycosylation. Glycosylation was conducted at varying relative humidities (50%/65%/80%) and temperatures (40 °C/50 °C/60 °C) using a response surface central composite design. Degree of glycosylation (DG) ranged from 39.3 to 52.5%, 61.7 to 70.9%, and 81.2 to 94.8% at 40 °C, 50 °C, and 60 °C, respectively (P values < 0.0001). Denaturation temperatures of all DGs ranged from 111.6 °C to 114.6 °C, while unmodified/native BMSPI had a value of 113.2 °C. Surface hydrophobicity decreased to approximately 60% when the DG was maximal (94.8%). Solubility decreased almost 90% when the DG was maximal in comparison to the native BMSPI (62.0%). Emulsifying activity increased from 0.35 to 0.80 when the DGs were ≥80%, while emulsion stability increased from 63 to 72 min when the DGs were greater than 70%. A similar trend was observed with foaming capacity and foaming stability of the glycosylated proteins. This glycosylated BMSPI with improved emulsifying and foaming properties could be used as an ingredient in food products where such properties are required.     

Evaluation of protein quality of peanut (Arachis hypogaea) cultivars using Tetrahymena pyriformis

Protein quality of eight peanut (Arachis hypogaea L) cultivars was evaluated using chemical, biological and microbiological techniques. The chemical score for S-amino acids and lysine in peanut cultivars ranged from 37 to 50 and 47 to 55%, respectively. Protein efficiency ratio and relative nutritive value of peanut proteins varied significantly from 1.45 to 1.76 and 45.6 to 54.2%, respectively. Relative nutritive value was significantly associated with chemical score (r = 0.98**) and protein efficiency ratio (r = 0.88**), and therefore could be used as a quick method to measure protein quality of peanut cultivars.     

Development of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) on sorghum milling fractions

A series of tests was conducted to determine if Tribolium castaneum (Herbst), the red flour beetle, could survive on six milled sorghum fractions: Bran, Coarse Grits, Fine Grits, Flour, Red Dogs, and Shorts. In the first test, parental adults were exposed on the fractions, removed, and then the fractions were held for six-seven weeks at 27 °C. Late instar larvae and progeny adults were present in all fractions. In the second test, at least 80% of single neonates (1-2-day-old larvae) held on 1 g of a fraction at 27 °C for seven weeks were able to complete development to the adult stage. In the final test, individual neonates were held on 1 g of a fraction at 37 °C, 32 °C, 27 °C, or 22 °C. Time to adult emergence at each temperature ranged from 17 to 23 days, 21–27 days, 28–50 days, and 67–113 days, respectively, depending on the specific fraction. Logistic functions were compared for mean developmental times for each temperature-fraction combination. The six fractions were also analyzed for ash, fat, fiber, moisture, protein, and starch content. The fractions varied with respect to these chemical constituents; fat and moisture content were negatively correlated with development in some comparisons, though overall there was no correlation between these chemical components and neonate development on the fractions. Temperature had an obvious effect on neonate development, which has implications for assessing risk of pest infestations inside sorghum mills during warmer months of the calendar year. In addition, T. castaneum will reproduce and develop on all of the sorghum fractions included in this study, which are commonly generated during the sorghum milling process. Sanitation and removal of residual materials such as the measured fractions could also help with overall pest management of T. castaneum.     

The development,fecundity and longevity of Dermestes ater Degeer (Coleoptera: Dermestidae)

Larvae of Dermestes ater Deg. were bred on a diet of fishmeal, wheat germ, yeast and cholesterol at 15, 20, 25, 30 or 35°C with a constant 65% r.h. and at 25°C with 40, 50, 60, 70 or 80% r.h. Whenever possible emerging adults were paired and kept under the same conditions to determine longevity and fecundity. Eggs laid at 25°C and placed at 15°C failed to hatch. The egg period at 25, 30 and 35°C averaged 4–5 days and at 37.5°C it was about 3 days. Egg hatch was low approximating to about 40% except at 37.5°C where it was only just above 10%. No viable adults emerged at temperatures below 25°C. Development was completed in about 40 days at 30 and 35°C and at all humidities tested at 25°C (taking about 50 days at 80% r.h. and 65–70 days at 40% r.h.). Mortality was low at 25 and 30°C (less than 30%) but high at 35°C (90%). Fifty per cent of adults were dead after about 100 days at 25°C, after about 30 days at 30°C; the two adults at 35°C survived just over 20 days. A pre-oviposition period averaging about 33 days at 25°C and 4 days at 30°C was followed by an oviposition period of about 2 months. The number of eggs laid was very variable (0–135) as was the percentage hatch (0–69%). The results are compared with those obtained by other authors.     

Rheological Properties of Pasteurized Liquid Whole Egg During Frozen Storage

Effects of pasteurization and frozen storage on the rheological behavior of liquid whole egg (LWE) were studied using a cone and plate viscometer. Homogenized LWE control and LWE heated at 60°C, 64°C or 68°C for 3.5 min were evaluated during 80 days storage at ?24°C. Thixotropic behavior was observed in all frozen samples. Apparent viscosity increased with pasteurization and frozen storage. Unpasteurized LWE exhibited Newtonian behavior throughout storage. Pasteurized LWE flow properties changed from Newtonian to Bingham Plastic during storage. Identification of rheological parameters will help understand the molecular changes that occur during the processing and storage of LWE and help processors monitor LWE quality.     

Amino acid profiles and quality from lotus seed proteins

BACKGROUND: Protein composition, amino acid profile and nutritional value of the lotus seed and its Osborne fractions were investigated. The seed was rich in protein with 19.85%, and showed well balanced amino acid composition compared with FAO/WHO pattern, Its nutritive properties were similar to those observed in the reference soybean protein. Phenylalanine, tyrosine, leucine and lysine were the limiting amino acids in the seed proteins. The albumin and globulin were the main protein fraction, the amino acid profile and nutritional value were close to the seed protein. RESULTS: Changes in transition temperature and thermal stability were observed through different solvent extractions. Albumin possessed the predominant thermal stability (81.4 °C) followed by globulin (74.49 °C), prolamin (69 °C) and glutelin (65.6 °C). So, solvent compositions influence the profile of AAs and their nutritive value, and aqueous solvent with 0.1 mol L^?1 NaCl was an efficient protein solubiliser. CONCLUSION: The results indicated that the extraction processes influenced the lotus seed protein quality and thermal stability. Overall, the study revealed that the lotus seed protein was nutritionally well‐balanced protein and might be of significant importance in the formulation of diets for humans. © 2012 Society of Chemical Industry     

Enhanced Thermal Resistance of Salmonella in Whole Muscle Compared to Ground Beef

Irradiated beef (whole ‐muscle and ground product with identical fat, protein, and moisture composition) was exposed to a Salmonella‐ inoculated marinade and heated in brass tubes in a water bath at 55 °C, 60 °C, and 62.5 °C. The bacterial load and thermal lag time were similar (α= 0.05) for both whole and ground muscle; therefore, all samples had equivalent composition, inoculation levels, and thermal histories. Assuming 1st‐order kinetics, the inactivation rate constants (k values) in whole muscle were 50% lower than those in ground product at each temperature (P = 0.0001), and Arrhenius‐type models described the temperature dependency of k (R² > 0.95). Because thermal processing regulations are generally based on ground product studies, thermal process validations for meat and poultry products may need to consider the physical state (whole ‐muscle versus ground) of the product being manufactured.     

Nutritive Quality of Fermented Sorghum

The relative nutritive value (% RNV) of sorghum fermented at 25°C and at 35°C increased significantly (P < 0.05) over the % RNV of the control. During the consecutive 7-day fermentation at 25°C, time had no effect on the % RNV. The highest % RNV (56.45%) was achieved at the end of 1 day. Fermentation at 35°C was influenced by the time, with the highest % RNV (61.11%) obtained at the end of 7 days. Available lysine and methionine increased substantially (P < 0.01) over the control when sorghum was fermented at 25°C or 35°C for 4 days. Sorghum fermented at 25°C and at 35°C had methionine contents of 25.68 and 26.79 mg/g N, respectively, whereas the control contained only 11.25 mg/g N. Lysine levels were 33.2 and 34.5 mg/g N in sorghum fermented at 25°C and at 35°C, respectively, whereas the control contained 9.1 mg/g N. None of the available B-vitamins studied was altered significantly in the fermented samples.     

Environmental factors influencing the development and rate of increase of Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) on stored maize

Temperature, relative humidity (r.h.), food density, and maize (corn) cultivar (CV) influenced oviposition, development and intrinsic rate of increase of Prostephanus truncatus (Horn). The lower and upper limits for complete development were 25 and 32°C at 40% r.h.; 18 and 37°C, at 70% r.h.; and 20 and 32°C at 90% r.h. The shortest developmental periods were 25.4 ± 0.2 days in ground maize, CV Golden Beauty, at 32°C, 70% r.h., and 24.1 ± 0.2 days in whole kernel maize, CV Pride 1108, at 32°C, 80% r.h. Ground maize at a density of 750 mg/cc promoted rapid development of larvae accompanied by lower mortality and fewer malformed adults than ground maize at a density of 450 mg/cc. P. truncatus laid 430 eggs per female in blocks of maize consisting of 6-cemented kernels during 22 weeks compared with 205 eggs per female in ground maize during 15 weeks, and 36 eggs in loose maize kernels during 4 weeks. Viable eggs were laid at 18°C, 70% r.h., and 32°C, 70–80% r.h. The rate of self-multiplication and the intrinsic rate of increase per week, were: 1.94–2.24 and 0.665–0.806, respectively, at 30–32°C, 70–80% r.h. The highest rate was on field maize, CV Pioneer 3993, at 30°C, 70% r.h. The wide range of temperatures and relative humidities at which P. truncatus can develop in maize favor its establishment in tropical and subtropical regions where maize is grown and stored.     

Flow Behavior of Liquid Whole Egg During Thermal Treatments

Costs of handling and loss of functional properties of frozen liquid whole egg (LWE) has stimulated interest in a refrigerated product. To maintain adequate shelf life at refrigeration temperatures a heat treatment more severe than normal pasteurization may be needed. To establish limits for the thermal treatment and to prevent possible damage to the pasteurization system due to coagulation of the product, flow properties of LWE during pasteurization were investigated. Utilizing a cone and plate viscometer, egg viscosity was determined at shear rates between 1.15 and 450 sec⁻¹. Test temperatures varied from 20-75°C and heat treatment durations ranged from 0.5-10 min. Percent protein denaturation for each treatment was also determined and correlated to the flow properties. Above 60°C viscosities were shear rate dependent while below this temperature flow properties were approximately Newtonian. Mathematical expressions were developed for viscosity as a function of time, temperature and shear rate.     

Comparative study of the nutritive value of casein heated by microwave and conventionally

The objective of this study was to compare the net protein utilisation, digestibility and biological value of casein solution heated by microwave or conventionally, ie on an electrically heated plate. Portions (500 ml) of an aqueous solution of casein (100 g litre^?1) were heated to a temperature of 80°C and subsequently kept at 80± 5°C for 2 min. The heating times of microwave and conventional heating were the same. Additional portions were subjected to a so-called abused treatment consisting of repeating the normal microwave or conventional heat treatment three times. Next, the nutritive value of heated and unheated casein was determined in a 10-day feeding study with Wistar rats. The net protein utilisation, digestibility and biological value of unheated casein were 61.1, 100 and 61%, respectively. Comparable values were obtained for casein heated by microwave or conventionally. These results did not therefore indicate any decrease in nutritive quality of the protein by microwave heating or conventional heating under simulated household conditions.     

Influence of Temperature of Fermentation on the Nutritive Value of Lactic Acid Fermented Cornmeal

Cornmeal was fermented 4 days at 25°C 35°C 45°C, and 55°C. Relative nutritive value (RNV) and concentrations of available (free) lysine, methionine, and tryptophan were determined for cornmeal fermented at each temperature and for nonfermented corn. Corn fermented at 45°C had the highest % RNV and amino acid levels of any of the groups tested.     

Effect of Crystalline Structure on Oxidation of Fish Oil in Stearin:Fish Oil Mixtures

Effects of incorporation of stearin fraction into fish oil on crystallisation behaviour and oxidative stability of fish oil were examined. The stearin fraction (S₂₅) was obtained from step-wise dry fractionation of anhydrous milk fat at 25 °C. Analysis of fatty acid composition by gas chromatography showed that unsaturated fatty acids (89.3 %) were enriched in the fish oil whereas the S₂₅ typically comprises of saturated fatty acids (79.4 %). A series of S₂₅:fish oil mixtures (0:100, 25:75, 50:50, 75:25; 90:10 and 100:0) was prepared by mixing the S₂₅ and fish oil at 50 °C under flushing of nitrogen gas. Crystallisation and thermal properties and crystal structures of the mixtures were investigated by differential scanning calorimetry and small- and wide-angle X-ray scattering, respectively. The crystallisation/melting temperatures and crystallisation/melting enthalpies of the mixtures increased with increasing ratios of S₂₅ blended into fish oil. All mixtures showed similar crystal structures (double- and triple-chain length) and crystal polymorphs (α, β’ and β) at 4 °C. A decrease in S₂₅ fraction in the mixtures caused a higher proportion of triple-chain length crystal packing and β polymorph. Measurement of peroxide values of the mixtures upon storage at 8 °C for 42 days showed that blending as low as 25 % S₂₅ sufficiently delayed the lipid oxidation of fish oil by about two-fold and the rancidity threshold to 16 days instead of 9 days for fish oil only. This study demonstrates that mobility of oxygen and triacylglycerol (TAG) molecules in fish oil can be restricted by crystalline state of milk fat, in turn, limiting the propagation of oxidative reaction in fish oil.