发酵剂的筛选及其对搅拌型酸奶理化特性的影响

通过调查单菌株发酵特性、球菌/杆菌比例的选择、菌株复配后的性能,得到了4组优化的发酵剂配方。在不添加任何增稠剂的条件下,其发酵的酸奶在28d货架期内质构、后酸化程度表现优异且稳定。此外,为了预测酸奶货架期后酸化程度的强弱,比较了15组28d储存期实验与加速实验中所得的pH值及其变化趋势。结果表明,加速试验中趋于定值时的pH值可以作为判断后酸化程度强弱的先行指标。     

Effect of selected dairy starter cultures on microbiological, chemical and sensory characteristics of swine and venison (Dama dama) nitrite-free dry-cured sausages

The aim of this study was the evaluation of selected lactic acid bacteria (LAB) starter culture of dairy origin in the production of nitrite-free low-acid fermented venison (Dama dama) sausage (salame di daino) produced in a small-scale plant in Umbria (Italy), and their effect on microbiological, physico-chemical and sensorial properties of the products. Salame di daino was obtained with two different processes: with and without the addition of selected LAB starter cultures. Microbial counts of Enterobacteriaceae, coliform organisms and Pseudomonas spp. were lower in salami made with the addition of starter cultures. Staphylococcus aureus, Salmonella spp, and Listeria monocytogenes after the first week of ripening were only detected from control salami. Control salami were paler and harder, whereas those made with the addition of starter cultures were slightly saltier, juicier and in general more acceptable. Selected dairy-origin starter (SDS) cultures did prevent the growth of both indicators of food safety and of process hygiene and increased the acceptability of full-ripened salami.     

The effect of kimchi on the microbiological stability of fermented sausage

The effects of kimchi and freeze-dried kimchi-powder added to raw meat mixtures on the microbiological quality of fermented sausage were studied. The results clearly demonstrated that the lactic acid bacteria (LAB) integrated via the addition of kimchi as well as kimchi-powder were well adapted to the new habitat of fermenting sausage, reaching maximum numbers of 8.65-8.80log(10)cfu/g after 1-2days of fermentation. In all kimchi and kimchi-powder sausages, the growth of Enterobacteriaceae was completely inhibited throughout the processing period (<2log(10)cfu/g). The sausage batches containing more than 10% kimchi and 2% kimchi-powder showed no growth of S. aureus, whereas the control and another kimchi sausage batch reflected the growth of S. aureus (3.68-4.72log(10)cfu/g). As a result, the addition of kimchi (≥10%) and kimchi-powder to the sausage mixture prior to fermentation produced the microbiological stability required for fermented sausages.     

The effect of heat treatment and starter culture on colour intensity and sensory properties of Kulek cheese

The effect of the heat treatment on colour intensity and sensory properties of Kulek cheese made from raw milk with (RS) or without starter culture (R) and heated milk with starter culture (HS) was investigated during ripening. Colour L, a and b values of Kulek cheeses were determined for both interior and surface. The values for cheese R were 82.4 and 74.5 for L, ?5.2 and ?5.5 for a, 31.0 and 34.7 for b interior and surface respectively. The equivalents for RS cheese were 82.8 and 75.7 for L, ?4.8 and ?5.0 for a, 31.0 and 34.0 for b. The values for HS cheese were 88.9 and 88.4 for L and ?3.3 and ?3.3 for a, 22.8 and 24.2 for b. L values (lightness) were the highest in cheeses made from heated milk while b and negative a values were the highest in cheeses made from raw milk. Aroma scores of raw and heat‐treated milk cheeses made with starter were not significantly different. The panelists scored cheeses made from raw milk without starter as the best in body and texture.     

Biochemical and sensory characteristics of traditional fermented sausages of Vallo di Diano (Southern Italy) as affected by the use of starter cultures

In this study, two strains of Staphylococcus xylosus isolated from traditional fermented sausages of Vallo di Diano (Southern Italy) were used in combination with an acidifying strain of Lactobacillus curvatus as starter culture for the production of fermented sausages. Two starter formulation were developed combining the proteolytic but not lipolytic (prt(+), lip(-)) S. xylosus CVS11 with the L. curvatus AVL3 (starter S1) and the S. xylosus FVS21 (prt(-), lip(+)) with the same strain of L. curvatus (starter S2). Proteolysis and lipolysis were observed during ripening by the increase in total free amino acids (FAA) and free fatty acids (FFA), respectively. Such activities were observed in both started and non started sausages (control). Moreover, the proteolytic and lipolytic activities were detected in products started by both formulations irrespective of the presence of such activities in the strains used. Therefore, it was not possible to conclude whether the effect of proteolysis and lipolysis during ripening of the started fermented sausages was due to the activity of the starter cultures or to the action of meat endogenous enzymes.     

Effect of inulin and Lactobacillus paracasei on sensory and instrumental texture properties of functional chocolate mousse

BACKGROUND: This study evaluated the effect of a potentially probiotic bacteria (Lactobacillus paracasei subsp. paracasei LBC 82), added solely or together with the prebiotic ingredient inulin on instrumental texture attributes and sensory properties of a functional chocolate mousse during storage at 4 ± 1 °C for up to 28 days. RESULTS: The addition of Lactobacillus paracasei resulted in a firmer and more adhesive chocolate mousse. This effect was intensified with the presence of inulin in the synbiotic formulation (5.24 N and ? 0.956 N, respectively, for firmness and adhesiveness after 28 days of storage) (P < 0.05). L. paracasei population did not vary (P > 0.05) during storage (always between 7.27 and 7.35 log cfu g^?1), both for the probiotic and the synbiotic mousses. Synbiotic mousse differed from control and probiotic mousses during storage with respect to the color attribute. Moreover, both probiotic and synbiotic mousses presented taste, aroma and texture perceptions which were different from one another and from the control mousse after 14 and 21 days of storage. CONCLUSION: The use of inulin, together with the potentially probiotic strain of Lactobacillus paracasei subsp. paracasei, is advantageous, conferring potentially symbiotic potential to the chocolate mousse, as well as favorable texture and sensory properties. Copyright © 2008 Society of Chemical Industry     

Correlation between instrumental and sensory ratings by evaluation of some texture reference scales

The objective of this study was to investigate instrumental–sensory relationships of some texture scales using argentine foods as references. Textural characteristics of these foods were instrumentally investigated by the texture profile analysis technique. Principal component analysis (PCA) was used to describe the main attributes of the food samples. High Pearson’s correlation coefficients were found between hardness and fracturability (r = 0.94; P < 0.0001), hardness and gumminess (r = 0.71; P < 0.0001) and springiness and cohesiveness (r = 0.85; P < 0.0001). PCA identified two significant principal components, which accounted for 81.2% of the variance in the instrumental data. Additionally, a trained panel described the texture characteristics of the food samples according to the standard reference scales. The correlation curves showed nonlinear relationships (R² between 85.6% and 99.9%) which were used to predict sensory attributes of other food samples. Some texture attributes like hardness and fracturability were accurately predicted by mechanical properties, while others like cohesiveness and adhesiveness were less representative.     

The effect of sample temperature on instrumental and sensory properties of mashed potato products

The effect of sample temperature on texture, firmness and the sensory attributes of fresh and frozen/thawed natural and commercial mashed potatoes was studied. Scanning electron microscopy was used to obtain information on the structure of potato cells and how this is affected by processing. Various parameters were measured and were found to increase at 55 °C, these changes could be related to gelatinisation of the starch remaining in the products. In natural mashed potato, texture profile analysis (TPA) and firmness parameters were lower in the processed than in the fresh samples, indicating a weakening of the structure; this was confirmed by photomicrographs. In commercial mashed potato, TPA parameters measured at 55 and 65 °C and firmness parameters measured at 25 °C were higher in the processed samples, indicating enhanced structural strength; this was confirmed by photomicrographs. Firmness per gram of product was the best instrumental parameter for measuring texture in these products. The results of the different analyses indicated that 55 °C was the preferred temperature for consumption of mashed potatoes.     

Influencing cocoa flavour using Pichia kluyveri and Kluyveromyces marxianus in a defined mixed starter culture for cocoa fermentation

The potential impact of aromatic and pectinolytic yeasts on cocoa flavour was investigated using two defined mixed starter cultures encompassing strains of Pichia kluyveri and Kluyveromyces marxianus for inoculating cocoa beans in small scale tray fermentations. Samples for microbial and metabolite analysis were collected at 12–24 hour intervals during 120 h of fermentation. Yeast isolates were grouped by (GTG)₅-based rep-PCR fingerprinting and identified by sequencing of the D1/D2 region of the 26S rRNA gene and the actin gene. Pulsed Field Gel Electrophoresis (PFGE) was conducted on isolates belonging to the species P. kluyveri and K. marxianus to verify strain level identity with the inoculated strains. Furthermore, Denaturing Gradient Gel Electrophoresis (DGGE) was performed to follow yeast and bacterial dynamics over time including the presence of the bacterial inoculum consisting of Lactobacillus fermentum and Acetobacter pasteurianus. Yeast cell counts peaked after 12 h of fermentation with the predominant species being identified as Hanseniaspora opuntiae and Hanseniaspora thailandica. P. kluyveri and K. marxianus were found to compose 9.3% and 13.5% of the yeast population, respectively, after 12 h of fermentation whilst PFGE showed that ~ 88% of all P. kluyveri isolates and 100% of all K. marxianus isolates were identical to the inoculated strains. Despite never being the dominant yeast species at any stage of fermentation, the un-conched chocolates produced from the two inoculated fermentations were judged by sensory analysis to differ in flavour profile compared to the spontaneously fermented control. This could indicate that yeasts have a greater impact on the sensory qualities of cocoa than previously assumed.     

Species diversity and metabolic impact of the microbiota are low in spontaneously acidified Belgian sausages with an added starter culture of Staphylococcus carnosus

Quality of fermented sausages is affected by acidifying lactic acid bacteria (LAB) and colour- and flavour-promoting coagulase-negative staphylococci (CNS), whether or not used as starter culture. Artisan fermented sausages are often perceived as superior to industrial variants, partially because of the specific microbiota due to spontaneous acidification, which may be considered as an artisan characteristic. Therefore, two kinds of spontaneously acidified Belgian sausages were prepared (Belgian-type salami and Boulogne sausage), but with addition of a Staphylococcus carnosus culture. The Belgian-type salami was made from pork and beef, whereas the Boulogne sausage contained pork and horse meat. In all cases, Lactobacillus sakei was the dominant LAB species present on the raw materials and during fermentation, whereas enterococci remained present in the background. Enterobacteriaceae vanished after fermentation. The CNS species diversity on the raw materials was large and differed between the pork, beef, and horse meat. Nevertheless, this species diversity was annihilated during fermentation by the added S. carnosus culture. The volatiles fraction was mainly composed of aldehydes that originated from lipid oxidation and spices-derived compounds. Aromatic compounds that are typically associated to CNS activity, such as end-products from the metabolism of branched-chain amino acids, were not present in the Belgian-type salami and only marginally present in the Boulogne sausage. In conclusion, spontaneous acidification of Belgian-type fermented sausages leads to dominance of L. sakei and is no guarantee for bacterial contribution to the aroma profile when S. carnosus is added as a starter culture.     

Parenchyma cell microstructure and textural characteristics of raw and cooked potatoes

Cooking, microstructural and textural characteristics from four New Zealand potato cultivars (Agria, Nadine, Moonlight, and Red Rascal) were studied. Potatoes from the waxy cultivar, Nadine, showed lowest dry matter and starch content and also had highest cooking time compared to the other cultivars. The total colour difference, ΔE, indicative of browning and darkening during storage (for 1 h) of the peeled potatoes was observed to be highest for Red Rascal, followed by Nadine and was lowest for Agria. Light (LM) and confocal scanning electron (CSLM) micrographs revealed Moonlight and Red Rascal raw potato parenchyma cellular structure to be well integrated, showing compact hexagonal cells. Raw tubers from these cultivars also exhibited higher hardness and cohesiveness, as observed using texture profile analysis (TPA). Moonlight potato parenchyma retained cell wall outline after cooking and its cells were observed to be completely filled with gelatinised starch matrix, whereas the cellular structure of Nadine potato parenchyma was completely disintegrated after cooking. TPA results of cooked potatoes agreed well with these microstructural observations, with Moonlight cooked potatoes showing highest cohesiveness and hardness. The cell wall of parenchyma cells was observed to degrade partially upon cooking of potatoes, resulting in loosening of the cell wall microfibrils, as observed using transmission electron microscopy (TEM) of a selected potato cultivar. Also, the cell wall decreased in thickness after cooking. The remains of the primary cell wall along with some electron dense granular structures were observed floating in the cytoplasmic starchy matrix in potato tuber parenchyma cells.     

Ultrastructure of biofilms formed on barley kernels during maltingwith and without starter culture

Malted barley is a major raw material of beer, as well as distilled spirits and several food products. In the malting process, dry barley kernels are steeped in water which initiates germination and invigorates microbial growth on the kernels. In the present study, field emission scanning electron microscopy (FESEM) was used to visualize the microbial community within the tissues of barley kernels before and after the steeping, with and without Lactobacillus plantarum E76 added as a starter culture. The results show that the community of 10⁸ cfu g⁻¹ on dry, stored barley kernels increased 5–10 fold during the steeping forming a dense biofilm of bacteria and fungi with slimy exopolymeric matrix. FESEM revealed that crevices between the outer epidermis and the testa of sound barley kernels were heavily colonized with microbes, whereas there were only few microbes on the outer surface of the husks, in the aleurone layer or in the endosperm underneath an intact testa layer. The microbes frequently possessed appendages forming bridging them to the kernel and the individual microbial cells to each other. The L. plantarum added to the steeping water reduced the amount of exopolymeric matrix in the biofilm and improved the wort filterability.     

Effects of incorporating roasted lupin (Lupinus angustifolius) flour on the physicochemical and sensory attributes of beef sausage

The effects of incorporating lupin flour on the physicochemical and sensory characteristics of beef sausages were explored. Lupin (Lupinus angustifolius) flour was roasted, then hydrated to match the moisture content of beef meat. The beef sausage samples were manufactured for six treatments by replacing beef with hydrated lupin flour from 0% to 36% (w/w). Proximate analysis revealed that carbohydrate (dietary fibre) level was increased from 9.62% to 19.31%, whereas fat content was decreased from 11.62% to 7.91%. Inclusion of lupin flour increased the meat emulsion stability (fluid released decreased from 9.35% to 1.53%) and decreased cooking loss from 22.70% to 14.30%. Softer texture and greater adhesiveness were observed in lupin-incorporated formulations. Sensory evaluation indicated no significant difference between control and 12% lupin-enriched beef sausage formulation in appearance, aroma, flavour and overall liking, suggesting lupin flour can be added to beef sausage at this level without compromising consumer acceptance.     

感官评定及质构分析对不同糖源制作麻糬的品质研究

采用感官评定和质构分析(TPA)对不同糖源制作麻糬的品质进行研究.结果表明:添加不同糖源制作麻糬的品质有一定差异,添加同比例糖制作麻糬的抗老化效果以海藻糖为最好,麦芽糖次之,蔗糖最差,且添加量在一定范围(50％)时,随添加量的增加,抗老化效果总体趋势为增强;三种糖源制作麻糬的感官评分与TPA结果存在良好的相关性,硬度、胶粘性和咀嚼性与感官评分均在0.01水平或0.05水平上显著相关,相关系数大部分在-0.900以上,因而将硬度、胶粘性和咀嚼性作为麻糬质构评价的主要指标,并得出了感官评分以仪器测定为变量的线性回归方程.     

Human oral processing and texture profile analysis parameters: Bridging the gap between the sensory evaluation and the instrumental measurements

Studies in food oral processing are becoming increasingly important with the advent of the aged society. The food oral processing model of Hutchings and Lillford (Journal of Texture Studies, 19, 1988, 103–115) describes the structural breakdown and lubrication of ingested food before the swallowing stage, and has been revisited in the present article. The instrumental technique texture profile analysis (TPA) purports to mimic the first two bites of mastication and its ease of use has lured some researchers to use it without a critical eye. In this article, we consider inconsistencies in the Hutchings and Lillford model with the hope that it might be further refined. With regard to TPA we question the validity of the data generated and urge authors caution before they publish results from the test protocol. If results are published then the x‐axis should be viewed as deformation or strain, and not time. Hardness should be represented by the breaking stress. Adhesiveness should be measured at a medium strain taking into account the surface properties of the plunger. The ratio of the energy estimated by the area under the curve obtained from the second and the first bites (A₂/A₁) should be called recoverability and not cohesiveness.     

Effect of sodium chloride replacement and apple pulp inclusion on the physico-chemical, textural and sensory properties of low fat chicken nuggets

The effect of 40 percent sodium chloride replacement with salt substitute blend (potassium chloride, citric acid, tartaric acid and sucrose) and incorporation of apple pulp, at the levels of 8 (Treatment I), 10 (Treatment II) and 12 (Treatment III) g/100 g of formulation, on the various quality characteristics of low fat chicken nuggets was investigated. Emulsion and product pH values were significantly higher (P < 0.01) for the control when compared to treatments. Salt replacement and apple pulp addition resulted in significantly lower (P < 0.05) emulsion stability and cooking yield. Among low salt and low fat nuggets, the product with 12 g/100 g apple pulp had the highest moisture percent. Protein and ash contents were significantly lower (P < 0.01) in treatment products, whereas moisture protein ratio was higher. Incorporation of apple pulp significantly increased (P < 0.01) dietary fibre content, redness, yellowness and chroma index of the product. Textural properties of the products significantly decreased (P < 0.01) with substitution of common salt and addition of apple pulp. Sensory evaluation showed significant reduction (P < 0.01) in texture and overall acceptability scores of treatment products; however, scores were in the range of very good.     

Fat effect on physico-chemical, microbial and textural changes through the manufactured of dry-cured foal sausage Lipolysis, proteolysis and sensory properties

The effect of fat content on chemical traits related to dry-curing process (pH, moisture and water activity), color and textural properties and changes of free fatty acids and amino acids compositions during the processing of foal dry-cured sausages were studied. For this purpose, three batches (20 units per batch) of dry fermented sausages with different pork back fat content (5%, 10% and 20%) were manufactured; low fat (LF), medium fat (MF) and high fat (HF), respectively. Samples at 0days (mix before stuffing), and after 7, 14, 28, 42 and 49days of ripening were taken. The fat level affected color and textural parameters at the end of the process, showing dry-cured foal sausage with the higher level of fat, the highest values of luminosity and the least hardness. No significant differences (P>0.05) among batches were detected on total viable counts, lactic acid bacteria and Microccaceae during the process. Regarding lipolysis and lipid oxidation it can be deduced that the increase in the fat level encouraged the production of free fatty acids and 2-thiobarbituric acid reactive substances. At the end of the ripening individual free fatty acids followed this order: oleic, palmitic, linoleic and stearic acid, representing 82-95% of the total free fatty acids. Final level of TBARS index was in the worst case of 1.23mg MDA/kg of sausage. On the contrary, the batch with lesser fat content showed the highest levels of free amino acids at the beginning and at the end of the process, showing final values of 1.6%.     

The effect of pectin concentration on viscoelastic and sensory properties of processed cheese

The effect of pectin addition on viscoelastic properties of model processed cheeses with 40% w/w dry matter and 50% w/w fat in dry matter after 42 days of storage at temperature 6 ± 2 °C has been investigated using dynamic oscillation rheometry (plate–plate geometry; frequency range 0.1–50.0 Hz; temperature 20 °C). The role of pectin concentration (0.2%, 0.4%, 0.6% and 0.8% w/w) has been studied. Also, the sensory evaluation of samples has been made to assess cheese appearance, rigidity, spreadability and flavour. All samples with the pectin addition were more rigid and less spreadable compared with processed cheeses without pectin. With the increasing concentration of pectin the storage ( G ') and loss ( G ") moduli rose at the whole tested frequency range (0.1–50.0 Hz). Growing pectin content resulted in the decrease in loss tangent (the nature of gel was changed to more elastic material). The dependence of processed cheese rigidity on pectin concentration (in range 0–0.8% w/w) was not linear. The appearance and flavour were not worse by pectin addition.