Influence of Annealing Temperature on Tg′ of Cooked Rice Stick Noodles

T_g′, a glass transition temperature under conditions of maximal freeze concentration, is important to the stability of frozen food. The procedures for using differential scanning calorimetry (DSC) to measure T_g′ have been reported under different experimental conditions. The aims of this study were to investigate the T_g′ of cooked rice stick noodles, and to determine the effect of the annealing temperature on its T_g′ value using DSC. Cooked rice stick noodles in aluminum DSC pans were scanned from ?60°C to 25°C at 5°C/min. to locate the apparent T_g′, which was ?5.3°C in the non-annealed state. When subjected to 4 different annealing temperatures of ?2, ?6, ?8 and ?10°C for 15 minutes, the T_g′ of cooked rice stick noodles was ?5.3, ?4.0, ?4.2, and ?4.9°C, respectively. The value of T_g′ was clearly observed in the annealed sample at ?6°C. The annealing process allowed time for the maximum formation of ice. This study showed that annealing at a temperature slightly below T_g′ gave a higher and more accurate value.     

Digestibility and immunoreactivity of soybean β-conglycinin and its deglycosylated form

IgE-mediated allergy to soybean may be connected to an incomplete protein digestion causing an inappropriate immune response in the gut. The aim of this study was to gain insight on the digestibility and immunoreactivity of β-conglycinin and its deglycosylated form. To achieve this goal both proteins were digested mimicking gastrointestinal physiological conditions. Digests were characterised by SDS–PAGE, MALDI-TOF-MS and immunological assays. Data on IgG binding western blot provided key information related to the composition of the digests indicating that whereas deglycosylated β-conglycinin was completely removed by gastrointestinal digestion, α and β subunits of β-conglycinin glycoprotein partially survive the process of digestion. Such differential digestive behaviour might be influenced by glycan moieties, at least to some extent, and should be an additional factor to be considered on its potential allergenicity. Results also support the existence of linear epitopes in the three subunits (α, α′, and β) of both protein forms.     

Effect of Different Cooking Conditions on the Pasting Properties of Flours of Glutinous Rice Varieties from Lao People’s Democratic Republic

The effect of different rehydration temperatures (30, 40, and 50°C) and cooking times (2.7, 4.7, 6.7, 8.7, and 10.7 min) at 95°C on the pasting properties of three glutinous varieties (Thadokkham-11, Thadokkham-8, and Hom Mali Niaw) from Lao People’s Democratic Republic was investigated using rapid visco analyzer. Non-glutinous varieties (IR64 and Doongara) were also analyzed to compare glutinous (amylose <4.5%) and non-glutinous (amylose >15%) varieties. All rice flours took up water at significantly (p < 0.05) higher rates in the case of increased temperature and soaking time, resulting in a decrease in the onset temperature for pasting. Among the glutinous rices, Thadokkham-8 showed a significant (p < 0.05) decrease in peak viscosity in response to increased rehydration time and temperature. For this variety maximum viscosity (2403.3 mPas) was observed at 1 min of rehydration at 30°C and minimum viscosity (1852.0 mPas) at 15 min of rehydration at 50°C. The viscosity values of Thadokkham-11 and Hom Mali Niaw varieties increased to their highest values (1608.7 and 1477.7 mPa.s, respectively) with an increase in temperature to 40°C for 1 min. In general, the glutinous rices produced weaker gel than non-glutinous rices. Extended holding at cooking temperature (95°C) had a more significant (p < 0.05) effect on the glutinous varieties Thadokkham-8 and Thadokkham-11 than on the non-glutinous varieties (IR64 and Doongara) used in this study.     

Modified Atmosphere Packaging Technology of Fresh and Fresh-cut Produce and the Microbial Consequences—A Review

Modified atmosphere packaging (MAP) technology offers the possibility to retard the respiration rate and extend the shelf life of fresh produce, and is increasingly used globally as value adding in the fresh and fresh-cut food industry. However, the outbreaks of foodborne diseases and emergence of resistant foodborne pathogens in MAP have heightened public interest on the effects of MAP technology on the survival and growth of pathogenic organisms. This paper critically reviews the effects of MAP on the microbiological safety of fresh or fresh-cut produce, including the role of innovative tools such as the use of pressurised inert/noble gases, predictive microbiology and intelligent packaging in the advancement of MAP safety. The integration of Hazard Analysis and Critical Control Points-based programs to ensure fresh food quality and microbial safety in packaging technology is highlighted.     

Photocatalytic and Photochemical Oxidation of Ethylene: Potential for Storage of Fresh Produce—a Review

The phytohormone ethylene exerts numerous beneficial and detrimental effects on postharvest quality and storage life of fruit and vegetables. In view of the current global challenge of reducing postharvest losses and waste of fruit and vegetables, the importance of ethylene management in the supply chain is paramount. For this purpose, various methods have been applied along the supply chain over the years; however, effective management of ethylene under real-time storage and transport conditions still remains a challenging task. This review explores the potential of photocatalytic and photochemical oxidation of ethylene for effective removal of this gas along the value chain of fruit and vegetables. These techniques involve the use of ultraviolet (UV) radiation with or without a catalyst. In photocatalytic oxidation, a semiconductor such as titanium dioxide is essential which acts as a photocatalyst on irradiation with UV light and thus facilitates the oxidation of ethylene at its surface, whereas in photochemical oxidation, extreme short wave (i.e. below 200 nm) vacuum ultraviolet radiation (VUV) consisting of high-energy photons eliminates ethylene in the gaseous state. This review gives a brief overview of current commercial techniques used in ethylene removal and then focuses on the photocatalytic and the photochemical oxidation of ethylene and the combination of both methods. The various factors affecting these processes are also discussed including the advantages and the drawbacks associated with them, and current applications of these methods in fruit and vegetable storage systems are highlighted. In addition, a future outlook on the application of these methods in postharvest storage of fresh produce is given.     

Digestibility and allergenicity of β-lactoglobulin following laccase-mediated cross-linking in the presence of sour cherry phenolics

β-Lactoglobulin (BLG) is an important nutrient of dairy products, but it represents a serious health risk in patients allergic to milk. Sour cherry (Prunus cerasus L.) extract (SCE) is frequently added as a natural food colour in composite foods, such as fruit yogurt, ice creams, frappés and milkshakes. The aim of this study was to investigate the potential of laccase to cross-link BLG in the presence of an SCE and to characterise the obtained products for their bioactivity.     

Quality of ‘Abacha’ from Fresh Cassava Roots and Dried Chips

This study was undertaken to determine the possibility of producing acceptable ‘abacha’ from dried chips. The ‘abacha’ slices were processed from dried cassava chips and fresh roots of four cassava varieties, TMS 98/2101, NR/87184, TMS 97/4779 and NR87184. The proximate composition, chemical and sensory properties as affected by the processing method and variety were evaluated. The proximate composition of the ‘abacha’ (on dry basis) showed moisture content range of 9.53 – 10.48%, protein 1.07 – 1.66%, ash 2.06 – 2.56%, fibre 1.72 – 1.95, fat 0.39 – 0.58% and carbohydrate content of 83.59 – 85.05%. The chemical composition of the wet ‘abacha’ slices showed pH of 5.60 – 5.80, total titratable acidity (TTA) of 0.047 – 0.063, and hydrogen cyanide (HCN) value of 7.80 – 10.41 mg/100 g. Generally, the TTA of the ‘abacha’ samples was not significantly (p > 0.05) affected by the method of processing ‘abacha’ and the variety used. Drying the wet ‘abacha’ reduced the pH to 5.20 – 5.30, increased the TTA to 0.213 – 0.230% and further reduced the HCN content to 7.32 – 8.63 mg/100 g. The HCN of all the ‘abacha’ samples processed from dried chips were significantly (p < 0.05) lower than the HCN of ‘abacha’ processed from fresh cassava root in some of the varieties. The lower sensory scores for ‘abacha’ made from dried chips shows that they were inferior to the ones from fresh cassava, although they were also accepted by the consumers. It also compared favourably with the ‘abacha’ processed from fresh cassava root in chemical qualities. This shows that when the need arises ‘abacha’ slices can be processed from dried cassava chips.     

Microbial Contamination of Fresh Produce: What,Where, and How?

Promotion of healthier lifestyles has led to an increase in consumption of fresh produce. Such foodstuffs may expose consumers to increased risk of foodborne disease, as often they are not subjected to processing steps to ensure effective removal or inactivation of pathogenic microorganisms before consumption. Consequently, reports of ready‐to‐eat fruit and vegetable related disease outbreak occurrences have increased substantially in recent years, and information regarding these events is often not readily available. Identifying the nature and source of microbial contamination of these foodstuffs is critical for developing appropriate mitigation measures to be implemented by food producers. This review aimed to identify the foodstuffs most susceptible to microbial contamination and the microorganisms responsible for disease outbreaks from information available in peer‐reviewed scientific publications. A total of 571 outbreaks were identified from 1980 to 2016, accounting for 72,855 infections and 173 deaths. Contaminated leafy green vegetables were responsible for 51.7% of reported outbreaks. Contaminated soft fruits caused 27.8% of infections. Pathogenic strains of Escherichia coli and Salmonella, norovirus, and hepatitis A accounted for the majority of cases. Large outbreaks resulted in particular biases such as the observation that contaminated sprouted plants caused 31.8% of deaths. Where known, contamination mainly occurred via contaminated seeds, water, and contaminated food handlers. There is a critical need for standardized datasets regarding all aspects of disease outbreaks, including how foodstuffs are contaminated with pathogenic microorganisms. Providing food business operators with this knowledge will allow them to implement better strategies to improve safety and quality of fresh produce.     

Combination of Moderate Vacuum Frying with High Vacuum Drainage—Relationship Between Process Conditions and Oil Uptake

This paper explores the possibility of combining moderate vacuum frying followed by post-frying high vacuum application during the oil drainage stage, with the aim to reduce oil content in potato chips. Potato slices were initially vacuum fried under two operating conditions (140 °C, 20 kPa and 162 °C, 50.67 kPa) until the moisture content reached 10 and 15 % (wet basis), prior to holding the samples in the head space under high vacuum level (1.33 kPa). This two-stage process was found to lower significantly the amount of oil taken up by potato chips by an amount as high as 48 %, compared to drainage at the same pressure as the frying pressure. Reducing the pressure value to 1.33 kPa reduced the water saturation temperature (11 °C), causing the product to continuously lose moisture during the course of drainage. Continuous release of water vapour prevented the occluded surface oil from penetrating into the product structure and released it from the surface of the product. When frying and drainage occurred at the same pressure, the temperature of the product fell below the water saturation temperature soon after it was lifted out of the oil, which resulted in the oil getting sucked into the product. Thus, lowering the pressure after frying to a value well below the frying pressure is a promising method to lower oil uptake by the product.     

Relationship between lipophilicity,bitterness and structure of phenyl β-d-glucopyranosides

The relationship between lipophilicity, structure and bitterness of phenyl β-d-glucopyranosides and their methyl ether derivatives was examined quantitatively using lipophilic and STERIMOL parameters, and selected indicator variables to assess position-specific substituent effects. The results indicate that the partial lipophilicity of the methoxyl groups is different for each substituent position of the glucose moiety and that the lipophilicity of a methoxyl group at position 2 is the largest. The results also show that the bitterness of phenyl β-d-glucopyranosides is determined primarily by the presence or absence of the methoxyl group at position 2 of the glucose moiety, not by the lipophilicity of the entire molecule.     

Relationship between pungency and food components – A comparison of chemical and sensory evaluations

The influence of food ingredients (water, starch, fat, and sugar), individually and in combination, on the sensory perception of the pungency of capsaicin was studied in model food systems using the time-intensity method. Furthermore, the transferability of the results obtained using model food matrices to complex matrices, such as convenience salsas, was investigated. Significant differences between the samples (p < 0.05) were examined by analysis of variance (ANOVA) followed by the Tukey-HSD post hoc test. A highly complex matrix and a high starch content reduced the perception of pungency in both the model food matrices and the convenience salsa products. Therefore, the time-related maximum intensity of pungency (I_max) was affected by other factors in addition to the capsaicin concentration.The total capsaicinoid content in the salsas was quantified by high-performance liquid chromatography–mass spectrometry (HPLC–MS) and correlated to the results of the sensory evaluation. The best correlation (R² = 0.8029) was observed for the total capsaicinoid content and the maximum intensity of pungency (I_max) in comparison to the duration of the total pungency perception T_Dur (R² = 0.5176) and the area under the curve (R² = 0.6898). The calculated regression models serve as an example of how empirical calculations can be generated and used in a specific context.     

Application of Visible and Near Infrared Hyperspectral Imaging to Differentiate Between Fresh and Frozen–Thawed Fish Fillets

The potential of visible and near infrared (VIS/NIR) hyperspectral imaging was investigated as a rapid and nondestructive technique to determine whether fish has been frozen–thawed. A total of 108 halibut (Psetta maxima) fillets were studied, including 48 fresh and 60 frozen–thawed (F-T) samples. Regarding the F-T samples, two speeds of freezing (fast and slow) were tested. The hyperspectral images of fillets were captured using a pushbroom hyperspectral imaging system in the spectral region of 380 to 1,030 nm. All images were calibrated for reflectance, followed by the minimum noise fraction rotation to reduce the noise. A region-of-interest (ROI) at the image center was selected, and the average spectral data were generated from the ROI image. Dimension reduction was carried out on the ROI image by principal component analysis. The first three principal components (PCs) explained over 98 % of variances of all spectral bands. Gray-level co-occurrence matrix analysis was implemented on the three PC images to extract 36 textural feature variables in total. Least squares-support vector machine classification models were developed to differentiate between fresh and F-T fish based on (1) spectral variables; (2) textural variables; (3) combined spectral and textural variables, respectively. Satisfactory average correct classification rate of 97.22 % for the prediction samples based on (3) was achieved, which was superior to the results based on (1) or (2). The results turned worse when different freezing rates were taken into consideration to classify three groups of fish. The overall results indicate that VIS/NIR hyperspectral imaging technique is promising for the reliable differentiation between fresh and F-T fish.     

Relationship between α-amylase degradation and physico-chemical properties of sweet potato starches

Six varieties of sweet potatoes, grown under identical conditions, produced starches that displayed different characteristics. Susceptibility to pancreatic α-amylase varied between starches produced by the different clones. Structural characteristics at various levels, such as ratio of major fractions, size of amylose, gelatinization temperature and granule morphology, were also different between clones. Correlating structural attributes with susceptibility led to the suggestion that granule structure, including amylopectin: amylose ratio and molecular associations, were important critical factors in the hydrolysis of sweet potato starch granules. High amylopectin content of sweet potato starch was associated with a high gelatinization temperature and correspondingly less susceptibility to α-amylase attack. The hydrolysis pattern was correlated with degree of hydrolysis. Extensive surface erosion was shown to indicate a high degree of hydrolysis, whereas less surface erosion indicated less degradation.     

Pre-concentration and Extraction of Aflatoxins from Rice Using Air-Assisted Dispersive Liquid–Liquid Microextraction

An easy and quick sample pretreatment method, air-assisted dispersive liquid–liquid microextraction (AA-DLLME), has been introduced for the isolation and enrichment of aflatoxins B₁, B₂, G₁, and G₂ from rice samples prior to HPLC-FLD analysis. The method has also been compared with immunoaffinity column clean-up (IAC) method. In the case of AA-DLLME, the dispersion of extractant is formed in the absence of a disperser solvent and with the help of air bubbles. Several crucial factors, including the volume and type of extraction solvent, the volume of aqueous phase, and the number of extraction cycles were studied to obtain the optimal conditions. Under the optimal conditions, the suggested technique showed linearity in the range of 0.08–10 ng/mL with low limits of detection (0.68, 0.68, 0.13, and 0.13 ng/g for aflatoxins B₁, G₁, B₂, and G₂, respectively) and good sensitivity with limits of quantification of 2.0, 2.0, 0.4, and 0.4 ng/g for aflatoxins B₁, G₁, B₂, and G₂, respectively. The proposed procedure was successfully used to evaluate aflatoxins (AFs) in rice samples and acceptable recoveries in the range of 76.0–109.3% with appropriate precision (RSD?<?14.2%) were obtained.     

Legume and Cereal Starches — Why Differrences in Digestibility? Part 1: Isolation and Composition of Legume (Greengram and Bengalgram) Starches

A range of starch granule populations varying in size and shape characteristics was isolated from greengram (CG) and Bengalgram (BG) flours. All the starches were non-ionic and exhibited single state swelling with hihg solubility in water, but extensive solubility in DMSO. The starch content of the different populations varied from 40-80%, whereas the protein and lipid contents of the isolates I to III were lower than those of the isolate IV. Their amylose content ranged between 32-46%. Brabender viscograms indicated low values for peak and setback viscosities in the case of BG starch compared to GG starch. Fatty acid analysis of the lipid fractions indicated predominance of palmitic acid. GG starch exhibited a slightly higher in vitro digestibility than BG starch.     

Using Wavelet Textural Features of Visible and Near Infrared Hyperspectral Image to Differentiate Between Fresh and Frozen–Thawed Pork

In this study, wavelet textural analysis was applied to hyperspectral images in the visible and near-infrared (VIS/NIR) region (400–1,000 nm) for differentiation between fresh and frozen–thawed pork. The spectral data of acquired hyperspectral images were analyzed using partial least squares (PLS) regression and five wavelengths (462, 488, 611, 629, and 678 nm) were selected as the feature wavelengths by the regression coefficients from the PLS model. The fourth-order daubechies wavelet (“db4”) was used to serve as the wavelet mother function for wavelet textural extraction of the feature images at the above selected feature wavelengths with the wavelet decomposition level from 1 to 4. Four textural features were calculated in the horizontal, vertical, and diagonal orientations at each level. Forty-eight textural features were extracted from each feature image and used to differentiate between fresh and frozen–thawed pork samples by least-squares support vector machine (LS-SVM) model. Wavelet texture extracted from all five feature images at first decomposition level was identified as optimal wavelet texture combination, resulting in the highest classification accuracy for the LS-SVM models (98.48 % for the training set and 93.18 % for the testing set). Based on the texture combination, the quality attributes of pork meat could be predicted with correlation coefficients of calibration (r _c ) of 0.982 and 0.913, and correlation coefficients of prediction (r _p ) of 0.845 and 0.711 for pH and thawing loss, respectively. The results showed the possibility of developing a fast and reliable hyperspectral system for discrimination between fresh and frozen–thawed pork samples based on wavelet texture in the VIS/NIR wavelength range.     

The influence of beverages on the stimulation and viscoelasticity of saliva: Relationship to mouthfeel?

The viscoelasticity and secretion rate of stimulated saliva depends on food and beverage related stimuli, and it is demonstrated that this may subsequently influence the sensory properties and particularly the mouthfeel and afterfeel associated with the product being consumed. Using saliva donated by twelve volunteers, it is shown that acidic beverages such as peach flavoured iced tea and a fizzy cola stimulate significantly higher flow rates of whole mouth saliva that has greater elasticity in comparison to that generated following stimulation by water. In comparison, mechanical action from chewing flavourless gum and the stimulation from sucking a mint also stimulate high flow rates of saliva, although it is significantly less elastic than that from acid-based stimuli. However, the viscosity of human whole mouth saliva is relatively insensitive to beverage type, chewing, or mint. It is speculated that the stimulation of highly elastic saliva in response to acidic beverages is a defence mechanism for protecting the teeth from acid erosion. A separate sensory panel was used to identify key mouthfeel attributes that are likely to be related to the response of saliva, including: tongue dryness, mouth moistness, amount of saliva, tongue sensation, and throat drying. These results indicate that saliva viscoelasticity and flow rate alter dramatically in response to what a consumer eats and drinks, and that this in turn may affect mouthfeel and other organoleptic properties.     

Physical and Pasting Properties of ‘Ofada’ Rice (Oryza sativa L.) Varieties

In this study, grain physical and pasting properties of ofada rice cultivated in South-West Nigeria was evaluated using Standard Evaluation System (SES) for rice with the aim of providing basic information for brand development and utilization of ofada in the development of novel food products. Results showed that size and shape of ofada rice ranged from 5.9 to 9.0 mm and 1.8 to 3.0 mm respectively. The 1000-grain weight was between 24.0 to 31.0 g. Percentage hull was significantly different among the cultivars, ranging from 16 to 21. Peak viscosity ranged between 112.7 and 152.8 BU, minimum, setback and final viscosities varied from 80.3 to 117.2 BU, 104.0 to 143.3BU and 190.8 and 232.3 BU respectively. Gelatinization temperature was not significantly different and varied between 64.1 to 64.7 °C. Significant difference (p < 5%) was observed among the samples in terms of minimum setback and final viscosities respectively. Significant negative association was observed between kernel length and gelatinization temperature (r = – 0.65), setback and gelatinization temperature (r = – 67) while positive correlation was observed between breakdown viscosity and peak viscosity (r = 0.86). The good pasting behaviour makes ofada flour good material for the production of stiff dough products, better palatability and water binding capacity while physical qualities give ofada an advantage during milling. This attributes could be exploited for the development of new varieties and utilization in food development of the ofada rice value-chain.