Co-rotating extrusion cooking impact on product characteristics using hulled kodo millet and hybrid maize flour

Vitamin A deficiency (VAD) is adamant in developing countries especially affecting pregnant women and children. Popular maize hybrid (CO6) contains higher β-carotene concentration (923 µg/100 g), is considered one of the prominent and cheapest sources of provitamin A for humans, to alleviate VAD. The present research explored an adequate combination of hulled Kodo millet, a valuable food source for diabetics with limiting carotenoid content (0.17 µg/100 g) and biofortified hybrid maize genotypes (CO6) in ratio 70:30. Studies on process loss of total carotenoids (273.17-388.65 µg/100 g) without affecting the expansion index (2.06-4.46), piece density (254.06-585.62 kgm-3), browning index (47.25-88.38%), and hardness (13.21-67.59 N) characteristics under the influence of feed moisture 12.5-17.5%, wet basis, die temperature 150-180 °C and screw speed 420-470 rpm was evaluated in a co-rotating twin-screw extruder, following a five-level three-factor central composite rotatable design. The investigated physical and total carotenoid contents alteration upon extrusion cooking will add a scientific knowledge base to produce healthier breakfast cereals with acceptable technological and nutritional characteristics.

Acrylamide content in starch based commercial foods by using high performance liquid chromatography and its association with browning index

The harmful effects of acrylamide (AA) are a major health concern for human beings. To find out the levels of AA content in commercial food products, 43 samples representing 3 important product categories (French fries, bakery biscuits, and branded biscuits) were procured from the local market in Allahabad, India. An assay of AA was done using HPLC-DAD. The LOD and LOQ for AA were 3.733 and 11.045 ng/μl, respectively. The AA recovery from ten standard solutions was 100.6 percent, indicating good extraction efficiency. Level of AA ranged between 144.35 and 781.17 μg/kg, 126.33-664.90 μg/kg, and 825.96-1143.15 μg/kg, in branded biscuits, bakery biscuits, and French fries, respectively. A strong and positive correlation of AA was found with HMF, a* value, BI and negatively with ΔE (P ≤ 0.01). It is concluded that a high browning index is significantly associated with AA content and can be used as a screening food to reduce the intake of AA in the diet.

Effect of thermosonication on quality attributes of hog plum (Spondias mombin L.) juice

The use of thermosonication (TS) technique to preserve the qualities of fruit juice as an alternative to conventional pasteurization has attracted research interest in recent times. In the present study, freshly prepared hog plum juice (control), and the juice samples subjected to pasteurization (90 °C for 60 s) and thermosonication (40 kHz, 400 W at 40, 50 and 60 °C each for 5, 10, 20 and 30 min) were each analyzed for physicochemical, bioactive, microbial and sensory properties. After treatment, no significant changes in pH, total soluble solids and titratable acidity were observed. Notably, TS at 40 and 50 °C significantly (p < 0.05) improved color parameters, cloudiness and browning index. Furthermore, thermosonication increased ascorbic acid (11.40-18.55%), total phenolic content (17.98-18.35%), carotenoids (2.19-4.30%), flavonoids (10-16%) and antioxidant activity (32.52-48.5%) relative to the control. Both treatments significantly reduced the microbial count to non-detectable level after processing, while sensory attributes slightly improved. However, TS treatment at 60 °C decreased most of the quality parameters. Results showed that TS can improve quality, safety and economic potential of hog plum juice as a feasible alternative to pasteurization.

Application of sodium chloride and quince seed gum pretreatments to prevent enzymatic browning, loss of texture and antioxidant activity of freeze dried pear slices

ABSTRACT

In the study the effect of sodium chloride and quince seed gum solutions as immersion pretreatment to prevent enzymatic browning reaction in pear slices before freeze drying was evaluated. Four levels of gum concentrations (0%, 0.25%, 0.5% and 1%) and three concentrations of salt (0%, 0.25% and 0.5%) were used. Subsequently, freeze drying method was used to dry the pear slices and the qualitative, structural and sensory characteristics of dried pear slices were investigated. The moisture content of the dried pear slices decreased significantly with increasing sodium chloride concentration, while increasing the concentration of the gum significantly increased the moisture content (P < 0.05). Use of both immersion pretreatments were effective in maintaining the antioxidant activity and reducing browning index of the slides and with increasing concentration of the immersion solutions, the antioxidant activity loss decreased in the slices (P < 0.05). Electron microscopy study revealed that the microstructural changes of the drying process on the slices are very slight, although gum pre-treatment at the high levels made a layer on the surface of the pear slices which slowed down the transfer of water vapor molecules. By considering the results of qualitative, structural and sensory evaluations, using of immersion pretreatment with 0.25% gum and 0.25% salt solution to prevent enzymatic browning along with preserving the quality properties of pear slices prior to the drying process is recommended.

GRAPHIC ABSTRACT

SEM of cross section of dried pear slices after processing.

Preserving postharvest storage quality of fresh loquat fruits by using different bio-materials

Loquat fruits are known to have high nutritional contents and phytochemicals which are attributed with its health benefits. However, its storage life is reported to be very limited which negatively affect its marketability and consumption. Present study aimed to investigate the influence of seven different bio-materials or the combination of bio-materials on the postharvest life and storage quality of loquat (Eriobotrya japonica Lindl.) fruits var. 'Morphitiki'. The tested bio-materials or the combinations of current works was (1) OFI-Oputia ficus-indica extract; (2) OFI + Ns-Oputia ficus-indica extract + Nigella sativa oil; (3) OFI + PEx-Oputia ficus-indica extract + propolis extract; (4) OFI + C-Oputia ficus-indica extract + cinnamon oil; (5) Ns-Nigella sativa oil; (6) PEx-propolis extract and (7) CcEx-Chrysanthemum coronarium flower extract. As expected, weight loss showed an increasing tendency during storage period. Results showed that all of the tested bio-materials were effective in maintaining the postharvest quality of loquat fruits by reducing weight loss, positively affecting fruit firmness, preventing fruit browning and reducing decay incidence. Results suggested that loquat fruits can be stored with an acceptable quality for up to 35 days at 4 ± 1 °C and 95% relative humidity conditions, when treated with 0.5% Nigella sativa oil (Ns) or 0.5% propolis extract (PEx).

Sonication inhibited browning but decreased polyphenols contents and antioxidant activity of fresh apple (malus pumila mill, cv. Red Fuji) juice

Enzyme browning is the main challenge in the preparation of fresh apple juice. The influence of sonication on browning, as well as polyphenols and antioxidant activity of fresh apple juice was investigated. It was found that ultrasound can inhibit the browning of fresh apple (Malus pumila Mill, cv. Red Fuji) juice, but decreased the contents of total phenolic content (TPC), total flavonoid content (TFC) and chlorogenic acid and reduced the antioxidant activity. On the whole, ultrasound technology cannot be used to the antibrowning of fresh apple (Malus pumila Mill, cv. Red Fuji) juice.

Physical and sensory properties of ready to eat apple chips produced by osmo-convective drying

The low cost raw material, apple variety Idared, was turned into value-added product, apple chips. The apple chips were produced in a two-step process consisting of osmotic treatment and conventional drying. Osmotic treatment was carried out in 40 % glucose solution at room temperature, followed by convective drying at 105 °C, till reaching water activity of 0.3. Mechanical properties of the apple chips measured by compression and penetration tests were correlated with the sorption properties. The low browning index, 25.5 and high whitening index, 63.7, proved the good retention of the color of the apple chips. The instrumental characteristics of the apple chips were correlated with the sensory characteristics of the product. The new product was accepted by the 95 % of the panelists. The stored apple chips under modified atmosphere showed no significant changes in the quality parameters over 6 month period.

Effects of heating method and conditions on the evaporation rate and quality attributes of black mulberry (Morus nigra) juice concentrate

Black mulberry juice was concentrated by different heating methods, including conventional heating and microwave heating, at different operational pressures (7.3, 38.5 and 100 kPa). The effects of each method on evaporation rate, quality attributes of concentrated juice were investigated. The final juice concentration of 42° Brix was achieved in 140, 120, and 95 min at 100, 38.5, and 7.3 kPa respectively by using a rotary evaporator. Applying microwave energy decreased required times to 115, 95, and 60 min. The changes in color, anthocyanin content during the concentration processes were investigated. Hunter parameters (L, a, and b) were measured to estimate the intensity of color loss. All Hunter color parameters decreased with time. Results showed that the degradation of color and consequently anthocyanins, was more pronounced in rotary evaporation compared to microwave heating method.