Effects of sunflower honey on the physicochemical,microbiological and sensory characteristics in set type yoghurt during refrigerated storage

The primary purpose of this research was to monitor the influence of sunflower honey addition (2%, 4% and 6% w/v) to yoghurt milk on survival of the microbial flora of yoghurt and the physicochemical and sensory characteristics during refrigerated storage for 4 weeks. The water activity decreased according to the addition of honey with higher concentrations in the storage period (4°C). At the end of fermentation, pH values of yoghurt samples ranged between 4.33 (without honey) and 4.52 (addition of honey with 6%). The highest water holding capacity, consistency and the lowest brightness values were determined in the groups produced with 6% honey addition. The water holding capacity and a* (redness) values of the honey incorporated yoghurt samples increased during storage. Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus values of the yoghurt with honey increased compared with the control group samples (P < 0.01). Addition of honey to yoghurt milk has affected the vitality of the characteristics starters in the incubation and storage time of the yoghurt samples (P < 0.01). Optimum sweetness was obtained with the samples containing 4% honey level.     

Physicochemical characteristics and sensory optimisation of pineapple leather snack as affected by glucose syrup and pectin concentrations

Effects of glucose syrup (2%, 4%, and 6%) and pectin (0.5%, 1.0%, and 1.5%) concentrations on physicochemical characteristics and sensory acceptability of machine‐formed pineapple leather snack were investigated. Changes in glucose syrup and pectin concentrations significantly affected velocity of forming and total soluble solids content of pineapple paste, but did not affect thickness of pineapple leathers. Increasing pectin concentrations generally increased redness (a*) and yellowness (b*), and hardness (tensile force and work) while decreased moisture content and a_w of pineapple leathers. Two most acceptable pineapple leathers were prepared with 6% glucose syrup and 0.5–1.0% pectin. Increasing pectin concentration from 1.0% to 1.5% negatively affected toughness acceptability, which was attributed to reduced moisture and a_w, and increased tensile force and work. The optimum formulation range consisted of 3.5–6.0% glucose syrup and 0.5–1.0% pectin, yielding products with acceptability scores of 6.7–7.3 (on a 9‐point hedonic scale) for appearance, sourness, sweetness, overall‐taste, toughness and overall‐liking.     

Carbohydrate-based fat replacers in the modification of the rheological, textural and sensory quality of yoghurt: comparative study of the utilisation of barley beta-glucan, guar gum and inulin

Barley beta‐glucan, partially hydrolysed guar gum and inulin were used in the processing of low‐fat yoghurts. The possible beneficial effects of carbohydrate fat replacers on the rheological, textural and sensory quality of low‐fat yoghurt‐based products were determined. Comparisons were made between the sample yoghurts made from a low‐fat milk base, and full‐fat and low‐fat yoghurt controls. The inclusion of the carbohydrate components reduced product syneresis and improved the texture and rheological properties of the low‐fat‐based products so that their quality characteristics were similar to yoghurt made with full‐fat milk. Both the type and also the amount of carbohydrate component altered product characteristics. Beta‐glucan addition at low level (0.5%) was effective in improving serum retention of the yoghurt and its viscoelastic nature (G′, G′ and tan δ). In contrast, higher levels (above 2%) of inulin and guar gum were needed to exert significant improvements in the textural characteristics of yoghurt. Sensory analysis conducted on the samples illustrated that the inclusion of carbohydrate‐based fat replacers could be successfully utilised to mimic full‐fat products.     

A novel bi‐enzymatic system for lactose conversion

The potential of β‐galactosidase (β‐GAL) and glucose isomerase (GLI) to enhance the sweetening power of lactose and to generate galactooligosaccharides (GOS) and lactulose was studied. UF‐permeates of skim milk, sweet whey, acid whey and lactose solutions were incubated with β‐GAL and GLI. Lactose hydrolysis (LH) was 96–99%, glucose isomerisation (GI) about 53%. On a scale from 0 to 5, the intensity of sweetness increased from 1 to 3. The bi‐enzymatic process was also applied to yoghurt manufacture. Because of the inhibiting effect of calcium on GLI, the incubation was performed in UF‐permeates of skim milk. LH in yoghurt was 94%, whereas GI was 36% on average. Whey syneresis in yoghurt decreased from 12% to 5%. The sweetness increased from 1.4 to 2.9 on average. Applying the bi‐enzymatic system to 40% lactose solutions led to synthesis of about 20% prebiotic GOS. Products, such as 6‐galactobiose, allolactose and 6‐galactosyllactose were identified. About 1% lactulose was generated. Lactulose‐derived oligosaccharides were not found.     

Nanoliposomes coencapsulating curcumin and vitamin D3 produced by hydration of proliposomes: Effects of the phospholipid composition in the physicochemical characteristics of vesicles and after incorporation in yoghurts

Nanoliposomes coencapsulating curcumin and vitamin D₃ (VD3) using different compositions of purified and unpurified lecithins were produced by hydration of proliposomes and characterised over 15 days of storage. The dispersions were incorporated to pineapple yoghurts produced in laboratory‐scale, which were also characterised. Results showed that curcumin and vitamin D₃ were retained in the nanovesicles up to 86.1% and 94.1%, respectively. Most of the parameters assessed for the yoghurt samples were within the limits required by the Brazilian legislation and the Codex Alimentarius. Finally, the enriched product was well accepted by the panellists with the purchase intention ranging from 53 to 75%.     

Impact of octenyl succinylated pearl millet (Pennisetum typhoides) starch addition as fat replacer on the rheological,textural and sensory characteristics of reduced‐fat yoghurt

The current study evaluated the impact of octenyl succinic anhydride (OSA)‐esterified pearl millet (Pennisetum typhoides) starch as a fat replacer (0.5, 1.0, 1.5 and 2.0%) on various characteristics of reduced‐fat yoghurt (1.5% fat). Firmness, flow point, storage and loss modulus increased with increasing levels of the OSA starch. The Herschel–Bulkley model was best fit for elucidating their pseudoplastic behaviour. Syneresis decreased considerably, whereas sensory acceptability improved with increasing OSA starch level. Owing to this reduced syneresis, improved structural strength and sensory acceptability, OSA‐esterified pearl millet starch functions as a fat replacer in reduced‐fat yoghurt.     

Effects of Gellan-Based Edible Coating on the Quality of Fresh-Cut Pineapple During Cold Storage

The effects of gellan-based [gellan gum 0.56 % (w/v), glycerol 0.89 % (w/v) and sunflower oil 0.025 % (w/v)] edible coating on the respiration rate, physico-chemical properties and microbiological and sensory quality of fresh-cut pineapple during 16 days of storage (5?±?1 °C, 85?±?10 % RH) were evaluated. Uncoated fresh-cut pineapple was stored under the same condition and served as the control. For cross-linking reaction which was necessary for gel formation of gellan gum, a 2 % (w/v) calcium chloride solution that contained 1 % (w/v) ascorbic acid and 1 % (w/v) citric acid (as antibrowning agents) was used. The results obtained show that the respiration rate and weight loss of gellan-based coated samples were significantly (p?<?0.05) lower than those of the uncoated samples during 16 days of storage at 5 °C. In addition, coated samples significantly (p?<?0.05) maintained the firmness and colour of fresh-cut pineapple during low-temperature storage as compared to uncoated samples. The results obtained in this study also indicate that pH, titratable acidity and total soluble solids of coated and uncoated samples showed little changes during 16 days of storage at 5 °C. Gellan-based formulation did not show any antimicrobial effect, and no significant (p?>?0.05) differences were found among total plate counts and yeast and mould counts for coated and uncoated samples. Total plate counts and yeast and mould counts for coated and uncoated samples reached 10⁶ CFU/g (limit of shelf life acceptance for fruit-based products recommended by the Institute of Food Science and Technology in the UK) after 12 days of storage at 5 °C. In addition, the scores for all sensory characteristics at day 12 were significantly (p?<?0.05) higher in coated samples as compared to control. Therefore, the results obtained in this study indicate that gellan-based edible coating formulation has the potential to maintain the quality of fresh-cut pineapple during low-temperature storage for about 12 days.     

Comparative effect of probiotic and paraprobiotic addition on rheological and sensory properties of yoghurt

Yoghurt was produced using killed cells of Lactobacillus acidophilus ATCCSD 5221 and Bifidobacterium animalis subsp. lactis BB‐12. The rheological and sensory properties of the yoghurt were investigated at the end of the fermentation. The results revealed that the samples made with killed cells gave the lowest storage modulus, loss modulus, stress crossover point and loss tangent. The frequency‐sweep of yoghurt samples containing paraprobiotics added before fermentation showed the highest correlation coefficient. In the case of sensory assessment, significant differences were indicated among treatments. Adding killed cells of B. animalis subsp. lactis BB‐12 before fermentation produced yoghurt with the highest total score, whereas samples containing killed cells of L. acidophilus ATCCSD 5221 and B. animalis subsp. lactis BB‐12 added before fermentation exhibited the lowest total score.     

Chemical and sensory changes of different dairy products during storage in packages containing nanocrystallised TiO2

The chemical changes of three types of cheese, yoghurt and kefir were evaluated during storage in packages containing TiO₂ with two different compositions of the mixed anatase–rutile phase. The influence of TiO₂ packaging during storage on titratable acidity and fat content and on the external aspect was investigated. Fourier Transformed Infrared Spectroscopy (FTIR) analyses were performed to establish whether the TiO₂ penetrated the food during storage. The results showed that the TiO₂ nanoparticles deposited on polyethylene surface significantly decreased acidity and fat content of the investigated cheese and yoghurt types. During storage in TiO₂ nanopackages, the change in chemical parameters is accentuated as the content of rutile grows from 2.8% to 6.9%. The sensory evaluation revealed that the dairy products stored for 11 days in TiO₂ nanopackages present similar colour, texture and flavour with that of the references; the samples stored in polyethylene film were found to be unacceptable.     

Iron‐encapsulated cold‐set whey protein isolate gel powder ‐ Part 2: Effect of iron fortification on sensory and storage qualities of Yoghurt

Iron was incorporated at 20–60 mg/kg of yoghurt using iron‐encapsulated cold‐set whey protein isolate gel powder (WPI‐Fe) and by direct addition of ferrous sulphate solution. The changes in physicochemical and sensory qualities of the yoghurt samples were determined over 14 days of storage. Quality attributes of the yoghurt fortified using WPI‐Fe particles at up to 60 mg iron/kg were similar to those of unfortified control samples, especially in terms of colour and flavour, while the samples fortified by direct addition of ferrous sulphate exhibited noticeable adverse effects even at 20 mg iron/kg.     

The effect of hydrolysed tragacanth gum and inulin on the probiotic viability and quality characteristics of low‐fat yoghurt

This study investigates the effect of supplementation of tragacanth gum (GT, 0.05% w/v), low molecular weight gum tragacanth (LMWGT, 0.5% w/v) and inulin (0.5% w/v) on the viability of Bifidobacterium bifidum and the quality parameters of low‐fat yoghurt during a three‐week storage period. The count of probiotics was found to be 7.8 log cfu/g in inulin, and LMWGT enriched yoghurts at the end of the storage period. The minimum water holding capacity and the maximum syneresis values were also obtained in the low‐fat yoghurt enriched with GT throughout the storage time. The samples containing inulin and LMWGT revealed sensory attributes that were judged superior compared to those in GT.     

Physico-Chemical,antioxidant activities,textural, and sensory properties of yoghurt fortified with different states and rates of pomegranate seeds (Punica granatum L.)

This study examines the effects of incorporating fresh, frozen, osmodehydrated, and dried pomegranate seeds, at different concentrations (5, 10, and 20%) on the physicochemical, antioxidant, textural, and sensory properties of yoghurt. Antioxidant activity, pH, acidity, syneresis, and color of yoghurt were also evaluated during the storage (28 days) at 4°C. The principal component analysis (PCA) was performed to assess the correlations between different yoghurt formulation and their sensory attributes. Data showed that the addition of pomegranate seeds reduced pH and modified the chromatics coordinate (L*, a*, b*, C*, h°) and firmness of the yoghurt samples. In addition, acidity, °Brix, and syneresis increased compared to the control. Thanks to their high anthocyanin content, pomegranate seeds considerably improved the antioxidant activity essentially for yoghurt enriched with frozen seeds. In addition, the supplementation of 20% of frozen seeds into yoghurt was the most appreciated by panelists and improved the sensory properties in comparison to other formulation. According to PCA, taste and appearance were the main criteria for the overall acceptability of yoghurt. After 28 days of storage, the reddish color was reinforced; however, the antioxidant activity of yoghurts was reduced. Overall, it can be concluded that pomegranate seeds can be used as a natural ingredient to develop a novel yoghurt with high nutritional properties.     

Effects of various whey proteins on the physicochemical and textural properties of set type nonfat yoghurt

In this study, the changes during storage in the physicochemical, textural and sensory properties of nonfat yoghurts fortified with whey proteins, namely whey protein concentrates (WPC), whey protein isolates and whey protein hydrolysates, were investigated. Enrichment of nonfat yoghurt with the whey protein additives (1% w/v) had a noticeable effect on pH, titratable acidity, syneresis, water‐holding capacity, protein contents and colour values on the 14th day of storage (P < 0.01). The addition of whey proteins to the yoghurt milk led to increases in the hardness, cohesiveness and elasticity values, resulting in improved textural properties. The addition of WPC improved the texture of set‐type nonfat yoghurt with greater sizes in the gel network as well as lower syneresis and higher water holding capacity. This study suggests that the addition of whey protein additives used for fortification of yoghurt gave the best textural and sensory properties that were maintained constant during the shelf life.     

Suitability of Oat, Millet and Sorghum in Breadmaking

Challenges and opportunities of minor cereals with poor viscoelastic value deserve a special attention in breadmaking applications due to their unique nutritional components. In a preliminary stage, the suitability of oat, millet and sorghum in breadmaking was assessed in simple binary wheat flour matrices in which wheat flour was replaced from 0% to 60%. The research allowed the quantification of grains (up to 30% for millet and sorghum and up to 50% for oat of wheat flour replacement) to be incorporated into the binary blended matrices providing minimization of techno-functional impairment and sensory depreciation of breads. Combinations of gluten, vegetable fat and a commercial mix of surfactants, ascorbic acid and antistaling enzymes were used to make breads with 10% increased level of wheat flour replacement by single oat, millet and sorghum in binary mixed samples. The quality profile of binary mixtures of oat–wheat (60:40 w/w), millet–wheat (40:60 w/w) and sorghum–wheat (40:60 w/w) was significantly improved in terms of keepability during storage, mainly for oat–wheat blends which stale at a similar rate than 100% wheat breads. Overall acceptability of highly replaced wheat breads deserved higher scores for oat and sorghum composite breads (7/10) than control wheat breads (6/10). Oat, millet and sorghum represent a viable alternative to make aerated breads with mitigated technological and sensory constraints based on non-viscoelastic cereals.     

Original article: Effect of modified atmosphere packaging using different CO2 and N2 combinations on physical,chemical, microbiological and sensory changes of fresh sea bass (Dicentrarchus labrax) fillets

The effect of different modified atmosphere packaging (MAPs) on physical, chemical, microbiological and sensory changes of sea bass fillets when stored at 4 °C and standard light conditions was investigated for up to 21 days and compared to a control batch stored in overwrap. Sea bass fillets were packed using different CO₂ and N₂ combinations (40% CO₂–60% N₂; 50% CO₂–50% N₂; 60% CO₂–40% N₂), and quality assessment was based on instrumental, chemical, microbiological and sensory analysis. The results showed that MAP extended shelf‐life of sea bass fillets from 7 days (overwrap packaging) to 14 days. Drip loss, pH values and thiobarbituric acid reactive substances (TBARS) measurements were higher in overwrap samples but no differences (P ≤ 0.05) were found between MAP samples. Bacteria grew most quickly and showed higher counts in overwrap samples followed by 40% CO₂–60% N₂; 50% CO₂–50% N₂ and finally 60% CO₂–40% N₂. Sensory analyses were in good relation with chemical and microbiological results establishing best scores and an extended shelf‐life for MAP samples especially in MAPs with high CO₂ levels.     

Sensory properties of soy yoghurts prepared from yellow and black soymilk using Streptococcus infantarius 12 and Weisellia sp. 4

BACKGROUND: Soy yoghurts containing enhanced bioactive isoflavone aglycones were prepared from combinations of yellow (YS) and black soymilk (BS) (YS:BS = 100:0, 70:30, 50:50 and 0:100, v/v) by fermentation with Streptococcus infantarius 12 and Weisellia sp. 4 at 37 °C for 10 h. Sensory properties of the bioactive soy yoghurts were investigated. Furthermore, other characteristics including the contents of isoflavones, viable cell numbers, pH, colour and DPPH radical scavenging activity were investigated. RESULTS: One hundred percent YS yoghurt showed the highest scores of all sensory attributes while 100% BS yoghurt was the lowest for colour and smoothness. The overall acceptability scores were 5.9 and 5.2 for 100% YS and 100% BS yoghurts, respectively (9‐point scale). The L‐values of soy yoghurts decreased as the percentage BS increased, indicating darkening of soy yoghurts. The contents of bioactive isoflavone aglycones (daidzein and genistein) in soy yoghurts remarkably increased (>1300 mg kg^?1) by fermentation. Viable cell numbers and pH of soy yoghurts ranged from 8.4 × 10⁸ to 9.6 × 10⁸ CFU g^?1 and 4.43 to 4.54, respectively. DPPH radical scavenging activity significantly increased as the percentage BS increased (P < 0.05). CONCLUSION: One hundred percent YS yoghurt was better for overall sensory properties while 100% BS yogurt was more bioactive in terms of the isoflavone aglycone contents and DPPH radical scavenging activity compared to other yoghurts. Copyright © 2008 Society of Chemical Industry     

Colloidal aggregation induced by the reduction in pH and the synthesis of new molecular structures during the milk fermentation process

The use of different inocula in the milk‐to‐yoghurt transformation influences the kinetics of the fermentation process. The aim of this work was to study the kinetics induced by Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (Lb–St). The milk‐to‐yoghurt transformation showed no delay in the production of lactic acid for yoghurt produced using Lactobacillus johnsonii with S. thermophilus (La1–St) or Lactobacillus casei with S. thermophilus (Lc1–St); the delays were 20–70 min and 40–80 min, respectively. The absence of delay was 1.0/min (Lb–St) as compared with 0.015/min (La1–St) and 0.7/min (Lc1–St). The kinetics was fitted using second‐order reaction.     

Survival of Lactobacillus casei and functional characteristics of reduced sugar red beetroot yoghurt with natural sugar substitutes

In this study, probiotic gel fermentation and functional characteristics of reduced sugar yoghurt with red beetroot bioactive components and steviol glycosides from Stevia rebaudiana extracts as natural source of noncaloric sweeteners were investigated. A significant increase in Lactobacillus casei viability and fermented gel network and a decrease in syneresis were determined in yoghurt sweetened with steviol glycosides and high content of red beetroot bioactive components such as total phenolics, anthocyanins and total antioxidant capacity (DPPH and FRAP). The survival of L. casei was maintained within probiotic and therapeutic levels (>9 log₁₀ CFU/g), due to the possible prebiotic effect of steviol glycosides and fermentable fibres and phenolic compounds of red beetroot during 28 days of cold storage of the probiotic yoghurts. Colour properties (L*, a*, b*, ΔE*, C*, h*) and such sensory properties as smoothness, sweetness astringency were significantly affected. The highest organic acid content was found in red beetroot enriched yoghurt with stevia, while the most dominant organic acids were butyric, lactic, malic and citric. As a result, it was determined that fermented milk products, which are supported by phytochemical and steviol glycoside interactions, have adequate nutritional effects, high probiotic viability and acceptable sensory properties     

Effect of water activity on the inactivation kinetics of Escherichia coli O157:H7 by electron beam in ground beef, chicken breast meat, and trout fillets

Water activity (a_w) of ground beef, chicken breast meat, and trout fillets was modified to intermediate (a_w 0.98–0.99) and lowest (a_w 0.94–0.96) levels. The meat samples with modified and unaltered (native, a_w 1.00) a_w were inoculated with Escherichia coli O157:H7 and subjected to electron beam (e‐beam). Survivor curves were plotted and the D₁₀‐values were calculated. The D₁₀‐values ranged from 0.22 kGy for trout at native a_w to 0.33 kGy for beef at intermediate, and chicken and trout at lowest a_w. Regardless of the species, a_w reduction increased E. coli resistance to e‐beam, suggesting that even small depletion of unbound water from food increases survival. The difference of the D₁₀‐values between the samples at intermediate and lowest a_w was insignificant. E‐beam could be used before a_w‐reducing techniques are applied to food products. However, this would require stringent microbial control following e‐beam processing. The ‘tailing’ of survivors was observed for some samples with reduced a_w.