Influence of drying conditions on colour,betacyanin content and antioxidant capacities in dried red-fleshed dragon fruit (Hylocereus polyrhizus)

In this study, drying of red-fleshed dragon fruit at different temperatures (40, 50, 60, 70 and 80 °C) and air velocities (1.0 and 1.5 m s⁻¹) was conducted under the specific humidity of 25 g H₂O kg⁻¹ dry air. The results showed that drying at higher temperatures resulted in shorter drying times. However, temperature and air velocity did not significantly affect the total betacyanin contents and antioxidant capacities in dried products. Seven betacyanins identified by LC-MS were betanin, isobetanin, phyllocactin, isophyllocactin, betanidin 5 –O-(6′O-3-hydroxybutyryl)-β-glucoside, isobetanidin 5 –O-(6′O-3-hydroxybutyryl)-β-glucoside and decarboxylated phyllocactin. In addition, the temperature increased the isomerisation of betacyanins. The most preferable condition for preserving the colour and betacyanin contents of red-fleshed dragon fruit was the drying at a temperature of 80 °C and air velocity of 1.5 m s⁻¹ since it could shorten the drying time and give a bright red colour to the dried product as well as it had no significant impact on the betacyanins.     

Effect of high pressure processing on yield,quality and storage stability of peanut paneer

Paneer was prepared from peanuts by soaking the nuts for 8 h followed by removal of skin, grinding, extraction of milk and coagulation using calcium sulphate (1% solution). In another method the peanut milk was high pressure processed at 600 MPa for 5 min before coagulation. The obtained paneer samples were vacuum packed and kept at refrigerated temperature (6 ± 1 °C) for storage and evaluated for physico‐chemical, sensory and microbial attributes. High pressure processing of milk before coagulation resulted in increase in paneer yield significantly (P < 0.05) as well as maintained the quality of the paneer to a better extent as compared to control during refrigerated storage for a period of 45 days.     

Microbiological and enzymatic activity of bovine whole milk treated by pulsed electric fields

Pulsed electric field (PEF)‐treated milk (25.7 kV/cm for 34 μs after preheating to 55 °C and holding for 24 s) was microbiologically stable for 21 days at 4 °C, and similar to thermally treated milk (63 °C for 30 min or 73 °C for 15 s). Alkaline phosphatase inactivation was comparable after PEF (preheating followed by PEF) and both thermal treatments. PEF treatment initially reduced xanthine oxidase (30%) and plasmin (7%) activities, but after 21 days of refrigerated storage these activities were similar to the initial untreated milk. During refrigerated storage of PEF (preheating followed by PEF) and thermally treated milk, lipolytic activity increased and pH levels decreased.     

Study on efficiency of betacyanin extraction from red beetroots

Red beetroots are rich in betalain pigments, which are divided into betacyanins (predominating in red beetroots) and betaxanthins. The objective of this work was to study efficiency of aqueous extraction of betacyanins from red beets. The experiment was conducted according to a central composite design, with the following variables: solvent pH (pH, 3.0–5.0), solvent‐to‐beetroot ratio (S/B, 1:1–5:1), solvent initial temperature (ST, 30–70 °C) and grinding time (GT, 2–10 min). Beetroots were ground with the solvent, filtered and evaluated for betacyanin contents. A highly significant model was obtained for betacyanin extraction efficiency (BEE), which was positively affected by ST and S/B, and inversely affected by pH. The most adequate extraction conditions were pH, 3.0; S/B, 5:1; ST, 70 °C and GT, 2 min. At such conditions, BEE was near 70%. The method is simple and produces a bright red–purple extract to be later dried or concentrated for use as a food colourant.     

Physico-chemical and structural changes of red-fleshed dragon fruit (Hylocereus polyrhizus) during fruit development

BACKGROUND: Determination of physico‐chemical (weight, length, diameter, stomatal density, respiration rate, colour, soluble solids concentration, titratable acidity, chlorophyll and betacyanin content) and structural changes of red‐fleshed dragon fruit (Hylocereus polyrhizus (Weber) Britton & Rose) was carried out from 5 to 35 days after pollination (DAP) in order to explain their growth, development, maturations and ripening stages. RESULTS: Fruit growth of red‐fleshed dragon fruit followed a sigmoid growth pattern. Significant changes in colour were obtained in both peel and pulp as DAP progressed, which were indicated by reductions of L*, C* and h° values as both changed from green to red–violet colour at ripening. Red–violet betacyanin was manifested earlier in pulp at 25 DAP, followed by peel 4–5 days later, and finally both peel and pulp turned full red–violet by 30 DAP. There was a significant increase in soluble solids concentration and titratable acidity with the continuous increase in betacyanin content as DAP progressed. CONCLUSION: The physico‐chemical and betacyanin accumulation of red‐fleshed dragon fruit changed as it developed, matured and ripened which coincided with structural changes. Copyright © 2010 Society of Chemical Industry     

Lipolysis and Oxidation in Ultra‐High Temperature Milk Depend on Sampling Month,Storage Duration,and Temperature

During storage, some factors (for example, storage duration and temperature) can affect milk stability and consumer acceptability. Thiobarbituric acid reactive substances (TBARSs), lipid classes, and fatty acid profiles in stored ultra‐high temperature (UHT) milk were analyzed to assess the effects of storage time and temperature on lipid oxidation and lipolysis. With storage duration up to 12 months, the milk fat phase was separated and showed high levels of oxidation and lipolysis, manifested as increased levels of TBARS and free fatty acids. High oxidation levels decreased the percentage of unsaturated fatty acids (UFAs) in triacylglycerol and phospholipids. Higher storage temperatures (20, 30, and 37 °C) resulted in a higher degree of fat aggregation, oxidation, and lipolysis compared with refrigerated storage (4 °C). Additionally, sampling month of raw milk (May, July, and November) affected the lipid profiles of UHT milk during storage, with more UFA oxidized in July than in the other 2 months.     

Pasteurised,microfiltered and lactose‐hydrolysed skimmed milk with added probiotics: Development and storage stability

Recently the food industry has been attempting to innovate its products to meet consumer demands for health benefits from their food. Thus, the objective of this research was to study the combination of technologies to obtain a pasteurised, microfiltered, and lactose‐hydrolysed skim milk with an extended shelf life and with added probiotics (PMLHSP). This PMLHSP was subjected to physicochemical, microbiological and sensory evaluations, plus its shelf life was estimated at 5 °C. The viability of the probiotics in this system was also evaluated during storage at 5 °C and indicated a shelf life of about 28 days. The probiotic culture added to the microfiltered skim milk presented good viability in the product throughout refrigerated storage, with counts of above 8 log CFU/mL.     

Sensitivity of bifidobacteria to oxygen and redox potential in non-fermented pasteurized milk

The effect of deaeration, cysteine addition and electroreduction of milk on the viability of various Bifidobacterium strains in pasteurized milk during refrigerated storage at +7 °C for 4 weeks was assessed. Preliminary assays in deaerated milks showed considerable variability to oxygen sensitivity among the eight strains examined during refrigerated storage. Three strains with different sensitivity were selected for subsequent assays. Assays on the effect of oxygen during growth at 37 °C were included in the screening and results suggest that the growth inhibition observed could serve as an indicator of the negative effect of oxygen on stability of bifidobacteria during refrigerated storage in similar oxygen conditions. The electroreduction treatment had a positive impact on the survival of two of the three cultures tested during the 4 week storage period at 7 °C. Addition of cysteine and deaeration alone had similar effects on cell viability during storage, suggesting that the benefit of electroreduction was mainly linked to its action of lowering the level of dissolved oxygen in the samples. Data from this study suggest that electrochemical reduction of milk, as well as deaeration or addition of reducing agents could be applied to enhance the survival of bifidobacteria during extended storage at 7 °C in milk.     

Effect of Pre-treatment and Drying Method on Colour Degradation Kinetics of Dried Salak Fruit During Storage

Effect of heat treatment on colour stability of dried salak fruit during storage was investigated by using hot air (40–90 °C), heat pump (isothermal and intermittent modes, 26–37 °C) and freeze-drying. Influence of pre-treatment on the colour property was studied as well by blanching the sample at three levels of temperature (50–70 °C). Total colour change (∆E*) was used to assess the colour degradation kinetics and quantify the degree of browning during processing and storage. It was found that the dried pre-treated sample under heat pump isothermal drying recorded the highest ∆E* value during storage followed by non-pre-treated samples under heat pump intermittent drying, freeze-drying, hot air-drying and heat pump isothermal drying. Weibull model is found to better fit the experimental data as compared with zero-order and first-order kinetics models. Analysis on the kinetics constants reveals that the heat treatment could affect the microstructure, water sorption properties and concentration of reacting species of the dried product. This in turn contributes to the colour changes of the dried product during storage.     

Probiotic monocultures in fermented goat milk beverages – sensory quality of final product

The aim of our study was to conduct a selection of the monocultures capable of providing the most attractive sensory features of the final product. Four fermented goat's milk beverages were produced with probiotic monocultures containing Lactobacillus (Lb. acidophilus La‐5, Lb. rhamnosus K3 and Lb. plantarum O20) and Bifidobacterium (Bif. animalis subsp. lactisBB‐12). A sensory analysis and microbiological assessment of fermented goat's milk beverages were made at the beginning of the study and after 3, 7, 10 and 14 days of refrigerated storage (5 ± 1 °C). We found that samples including monocultures Lb. plantarum O20 and Bif. animalis subsp. lactisBB‐12 were differentiated from other goat's milk beverages.     

Quality of fresh‐cut purple‐fleshed sweet potatoes after X‐ray irradiation treatment and refrigerated storage

The effect of X‐ray irradiation on the quality of fresh‐cut, refrigerated purple‐fleshed sweet potato (PFSP) cubes was investigated. Packaged sweet potato cubes were treated with 0, 250, 500, 750 or 1000 Gy X‐ray irradiation and stored at 4 ± 1 °C for 14 days. After 14 days, total aerobic bacteria counts were 4.1 and 3.2 log₁₀ CFU g^?1, and mould–yeast counts were 3.3 and 3.0 log₁₀ CFU g^?1 in 750 and 1000 Gy treated samples, respectively. Doses up to 1000 Gy did not affect the firmness, moisture content and anthocyanin content of PFSP cubes throughout storage. PFSP cubes' flesh colour did not change during the first week of storage, but lightness (L*) increased after 14 days. Also, irradiation doses at 750 and 1000 Gy decreased saturation (C*) significantly, producing duller flesh colour than controls. Results indicate that X‐ray irradiation treatment at doses up to 1000 Gy can reduce microbial populations while maintaining the physical quality and anthocyanin content of PFSP cubes up to 14 days of storage.     

Development of vacuum‐dried probiotic milk powder with Bacillus coagulans

The present study explored the possibilities of using Bacillus coagulans as a probiotic culture in vacuum‐dried milk powder. The operational drying temperature at 63 ± 2 °C under 0.7 kg/cm² pressure emerged as the best temperature at which to prepare dried milk powder within 4.5 h with a mean (±SEM) Bacillus coagulans B37 spore count of 8.78 ± 0.03 log cfu/g and moisture content of 4.82 ± 0.12%. The total spore counts in vacuum‐dried milk powder did not change (P > 0.10) at storage temperatures of 7 °C, 37 °C or 45 °C over a three‐month period.     

Effect of sub‐freezing storage (−6, −9 and −12 °C) on quality and shelf life of beef

Based on the results of low field nuclear magnetic resonance (LF‐NMR) in our current study (the frozen state of ?6, ?9 and ?12 °C were nearly the same with extremely low free water content), ?6, ?9 and ?12 °C was designated as sub‐freezing temperatures. The effects of sub‐freezing storage compared with conventional chilling (4 °C), superchilling (?1 °C) and conventional freezing (?18 °C) on the quality and shelf life of beef were analysed. Results showed that the shelf life of beef is extended to 84 and 126 day at ?6 °C and ?9 °C, respectively. However, the TVB‐N values of the samples stored at ?12 °C and ?18 °C remained below 15 mg/100 g even on 168 day. Furthermore, shear force, colour, pH, thiobarbituric acid reactive substances (TBARS) and sensory properties were also measured. Consequently, the sub‐freezing storage has significantly extended the shelf life of beef compared to chilling and superchilling (P < 0.05). Moreover, no significant difference (P > 0.05) was found between the indicators for quality and shelf life of samples stored at ?12 and ?18 °C throughout 168 days.     

Development of functional pectin edible films with fillers obtained from red cabbage and beetroot

The present study aims to develop through casting, functional composite edible films based on pectin using beetroot powder and red cabbage powder as fillers obtained from by-products of plant tissue industrialisation. Physico-chemical, mechanical, thermal properties and colour stability of the films along 30 days of storage (5–45 °C; absence of light) were evaluated. The moisture and the stress at break decreased, and the intensity of red colour and the hydrophobicity increased with the presence of fillers. According to the FTIR results, there was a good compatibility between matrix and fillers in the composites. Pectin films generated an enhanced stability of red colour after 30 days of storage at 5 and 25 °C and, in general, after 16 days for 45 °C, showing their suitability to be used as colouring agents for edible food packaging applications.     

Optimisation of bambara groundnut water extract and skim milk composition as cryoprotectant for increasing cell viability of Lactobacillus spp. using response surface methodology

Four legume water extracts, that is bambara groundnut, soya bean, red kidney bean and black bean as well as skim milk, were examined for their effectiveness in protecting Lactobacillus rhamnosus GG and Lactobacillus fermentum SK5 during the freeze‐drying and storage. Bambara groundnut water extract (BGWE) showed promising cryoprotective activity that was comparable to skim milk. BGWE and skim milk at 2–10% w/v and 5–20% w/v individually produced survival rates for both strains of 87–88%. To further optimise the synergistic cryoprotective medium, response surface methodology was employed. The optimal combination was 4.93% w/v BGWE and 11.68% w/v skim milk for L. rhamnosus GG and 5.17% w/v BGWE and 11.36% w/v skim milk for L. fermentum SK5 with survival rates of 95.17% and 94.36%, respectively. The storage life of freeze‐dried cells of both probiotics at 4 °C and 30 °C for 6 months was markedly improved when they were produced with these optimal combinations.     

Effect of different storage conditions on coagulating properties and cheese quality of Withania coagulans extract

The effects of different storage conditions on the coagulating properties of extracts of Withania coagulans berries were investigated in terms of coagulation time, pH and quality attributes of cheese prepared from buffalo milk. The extracts were stored under different conditions, viz. room temperature (27 ± 3 °C), refrigerated storage (4 °C), frozen storage (?20 °C) and lyophilisation. The milk‐coagulating activity of the plant extracts was measured on a fortnightly basis for a period of 5 months. There was a nonsignificant change in pH and the milk coagulating properties of the lyophilised extract. Physiochemical analysis revealed that cheese prepared with lyophilised extract retained the highest content of ash (2.3%), fat (23.8%), total solids (48.7%) and crude protein (22.7%), and resulted in the highest cheese yield (17.6%) compared to other tested treatments. Thus, it is concluded that lyophilisation has good potential for storage of vegetable extract coagulants.     

Changes in content of vitamins A and E in growing‐up milk throughout its shelf life

The stabilities of vitamins A and E were determined in 51 samples of growing‐up milk stored at 23, 30 and 37 °C for up to 9 months. Initially, the content of vitamin A and vitamin E was 330 RE μg/100 mL and 1.78 α‐TE mg/100 mL, respectively. Decreases in vitamin content were higher (P < 0.05) in formulas stored at 37 °C (from 330 to 111 μg RE/100 mL for vitamin A and from 1.78 to 1.16 mg α‐TE/100 mL for vitamin E). Over‐fortification of growing‐up milk could be recommended for vitamin E.     

Shelf life stability of red‐fleshed plum nectars: role of polyphenol fortification on quality parameters

The effect of polyphenol fortification of red‐fleshed plum nectars by addition of plum skin extract on the stability of quality, defined in terms of sensory attributes, phenolic composition and antioxidant activity, during shelf life storage was investigated. The sensory attributes were stable throughout the 3‐month storage period at 5 °C for the control and fortified formulations. Among the phenolic compounds measured only the anthocyanins decreased during the storage period; however, the total antioxidant activity was not affected. The loss of red colour was less pronounced compared to the loss of anthocyanins for both formulations. This might be attributed to enhanced co‐pigmentation as the content of the co‐pigment, neochlorogenic acid, increased, while flavonols remained stable during storage. Polyphenol fortification enhanced the retention of red colour, polyphenol content and total antioxidant capacity compared to the control formulation.     

Effect of gums on viability and β‐galactosidase activity of Lactobacillus spp. in milk drink during refrigerated storage

The viability and β‐galactosidase activity of four Lactobacillus strains in milk drink containing gums during 28 days of refrigerated storage at 4 °C were assessed. The population of Lactobacillus rhamnosus GGB101 and Lactobacillus rhamnosus GGB103 were maintained, whereas the population of Lactobacillus reuteri DSM20016 and Lactobacillus reuteri SD2112 significantly decreased. The recommended level of 6 log CFU g^?1 was exceeded for all tested trains throughout storage. The highest viable number of Lactobacillus rhamnosus GGB103 (8.76 ± 0.03 log CFU mL^?1) was obtained in the product containing carrageenan–maltodextrin. The addition of guar–locust bean–carrageenan led to 20‐fold increase in the level of β‐galactosidase activity for L. rhamnosus GGB101 (1208 ± 2.12 Miller units mL^?1) compared to the control (61 ± 2.83 Miller units mL^?1). Our results suggested that gums could be added to milk to improve viability and enhance β‐galactosidase activity of Lactobacillus.     

Changes in Quality and Nutritional Parameters During Refrigerated Storage of an Orange Juice–Milk Beverage Treated by Equivalent Thermal and Non-thermal Processes for Mild Pasteurization

The effects of high-pressure (HP) treatment (400?MPa at 42 °C for 5 min) and pulsed electric field (PEF) processing (25 kV/cm at 57 °C for 280 μs) on ascorbic acid, total carotenoids, total phenolic compounds and total antioxidant capacity (TEAC and ORAC) of an orange juice–milk (OJ-M) beverage along the storage time at 4 °C were compared with a conventional heat preservation technology used in industry (90 °C for 15 s). During storage, ascorbic acid, total carotenoids and antioxidant capacity (TEAC) depleted with time regardless of the treatment applied. Instead, total phenolic content and antioxidant capacity measured by the ORAC method increased at the end of the storage. Non-thermal-treated beverage had less non-enzymatic browning than the thermally pasteurized one. There were no significant variations in the hidroxymethylfurfural (HMF) content of the HP- and PEF-treated OJ-M, whilst a significant increase was obtained after thermal treatment. During refrigerated storage, HMF was always below the maximum values established. The HP treatments reduced the L* value of the treated beverages immediately after processing and during refrigerated storage and induced an increase in total colour differences of beverages treated by HP compared with PEF and thermally processed orange juice–milk. Hence, alternative methods such as HP and PEF may give new opportunities to develop orange juice–milk with an equivalent shelf life to that of thermally treated orange juice mixed with milk in terms of microbial, physicochemical and nutritional characteristics.