Determination of lactic microflora of kefir grains and kefir beverage by using culture-dependent and culture-independent methods

Abstract: In this study, we investigated the bacterial compositions of kefir grains and kefir beverages collected from different regions of Turkey by using culture‐independent and culture‐dependent methods. In the culture‐independent detection, 10 different species of bacteria were detected in total by using the polymerase chain reaction‐denaturing gradient gel electrophoresis (PCR‐DGGE) analysis of the 16S rRNA gene V3 region. Among these species, Lactobacillus kefiranofaciens was the most dominant one in the kefir grains, while Lactococcus lactis was found to be significantly prevalent in the kefir beverages. In the culture‐dependent detection, the primary differentiation and grouping of the isolates from kefir beverages and kefir grains were performed using repetitive sequence‐based PCR (rep‐PCR) fingerprinting, and the results were validated by 16S rDNA full‐length sequencing. According to the results of culture‐dependent methods, the most frequently isolated species were L. lactis, Leuconostoc mesenteroides, and Lactobacillus kefiri, respectively. Only 3 species, which are L. lactis, Lactobacillus acidophilus, and Streptococcus thermophilus, were detected with both culture‐dependent and culture‐independent methods. This study showed that the combination of both methods is necessary for a detailed and reliable investigation of microbial communities in kefir grains and kefir beverages. Practical Application: Due to their artisan‐ and region‐dependent microflora, kefir products can be a source of interesting lactic acid bacteria, either new taxa or strains with specific functional properties, which might be used for the development of new starter cultures and innovative food products. Therefore, an increasing demand exists for new strains that show desirable effects on the product characteristics Artisan dairy products are a candidate source of such microorganisms. For this reason, in this study, the bacterial compositions of kefir grains and kefir beverages obtained from different regions of Turkey were studied using culture‐dependent and culture‐independent molecular methods.     

Mixed messages: Ambiguous penalty information in modified restaurant menu items

Restaurant menu items from six national or regional brands were modified to reduce fat, saturated fat, sodium and total calories. Twenty-four items were tested with a current recipe, and two modifications (small and moderate reductions) for 72 total products. Approximately 100 consumers tested each product for acceptability as well as for desired levels of tastes/flavor, amounts of key ingredients and texture/consistency using just-about-right (JAR) scales. Penalty analysis was conducted to assess the effects of non-JAR ratings on acceptability scores. Situations arose where JAR ratings and penalty analyses could yield different recommendations, including large groups with low penalties and small groups with high penalties. Opposing groups with moderate to high penalties on opposite sides of the same JAR scale were also seen. Strategies for dealing with these observances are discussed.     

Generalized Pairwise Correlation and method comparison: Impact assessment for JAR attributes on overall liking

In product development using JAR (Just-About-Right) scales, it is important to identify precisely, which direction of a given attribute affects hedonic scores the most. The Generalized Pairwise Correlation Method (GPCM) is a non-parametric one and it is useful to rank JAR variables according to their impact on liking. This is done using appropriate statistical tests: the McNemar’s, the Chi-square, the Conditional Fisher’s and the Williams’ t-test. As GPCM requires one-directional variables, JAR data needs to be transformed based on the dummy variable approach. GPCM gives those attributes in that order, which should be increased/decreased to gain higher consumer liking scores. An order can be created according to the impact on liking, which order determines the development of product attributes, as well. The non-parametric tests incorporated in the method are able to identify smaller differences than other statistical methods. As a result, GPCM identifies more significant product attributes; hence, it can help product development processes even if other methods cannot.     

Nudging consumers for relevant data using Free JAR profiling: An application to product development

Nudging is nowadays often used in order to influence people’s behaviours. However, we are convinced that nudging can also influence people’s speeches. In a product development context, consumers are more and more integrated in the process: how integrate them in the most efficient way? Whereas formatted measures can be easily analysed but are far from the consumers, measures that seem to be closer to the consumers are often very difficult to analyse. A trade-off has to be found, in order to get data that are, at the same time, as close as possible to consumers’ mind and relevant for the ones who develop new products. In this context, we proposed a new strategy, based on the nudge theory, called “Free JAR Profiling”. Its first step invites consumers to classify products into 3 hedonic categories. This classification impact consumers’ speeches in a soft way as it places consumers in a hedonic state of mind and allows them to easily structure their thoughts toward product improvement keys. The second step invites consumers to assess the products according to their own vocabulary, but with a constraint on how they give their opinion, based on a JAR scale. This strategy allows to have access to oriented and structured data, which mix the consumer spontaneity strength and the R&D approach of JAR scales. The added-value and the relevance of these nudged data can be checked, and a Sentiment Mapping can be performed as a results representation.     

Questionnaire Design: Carry‐Over Effects of Overall Acceptance Question Placement and Pre‐evaluation Instructions on Overall Acceptance Scores in Central Location Tests

Question placement and usage of pre‐evaluation instructions (PEI) in questionnaires for food sensory analysis may bias consumers’ scores via carry‐over effects. Data from consumer sensory panels previously conducted at a central location, spanning 11 years and covering a broad range of food product categories, were compiled. Overall acceptance (OA) question placement was studied with categories designated as first (the first evaluation question following demographic questions), after nongustation questions (immediately following questions that do not require panelists to taste the product), and later (following all other hedonic and just‐about‐right [JAR] questions, but occasionally before ranking, open‐ended comments, and/or intent to purchase questions). Each panel was categorized as having or not having PEI in the questionnaire; PEI are instructions that appear immediately before the first evaluation question and show panelists all attributes they will evaluate before receiving test samples. Postpanel surveys were administered regarding the self‐reported effect of PEI on panelists’ evaluation experience. OA scores were analyzed and compared (1) between OA question placement categories and (2) between panels with and without PEI. For most product categories, OA scores tended to be lower when asked later in the questionnaire, suggesting evidence of a carry‐over effect. Usage of PEI increased OA scores by 0.10 of a 9‐point hedonic scale point, which is not practically significant. Postpanel survey data showed that presence of PEI typically improved the panelists’ experience. Using PEI does not appear to introduce a meaningful carry‐over effect.     

Identification of Drivers of Liking for Bar‐Type Snacks Based on Individual Consumer Preference

Understanding consumer hedonic responses on food products are of greatest interests in global food industry. A global partial least square regression (GPLSR) had been well accepted method for understanding consumer preferences. Recently, individual partial least square regression (IPLSR) was accepted as an alternative method of predicting consumer preferences on given food product, because it utilizes the individual differences on product acceptability. To improve the understanding of what constitutes bar‐type snack preference, the relationship between sensory attributes and consumer overall liking for 12 bar‐type snacks was determined. Sensory attributes that drive consumer product likings were analyzed using averaged‐consumer data by GPLSR. To facilitate the interpretation of individual consumer liking, a dummy matrix for the significant weighted regression coefficients of each consumer derived from IPLSR was created. From the application of GPLSR and IPLSR, current study revealed that chocolate and cereal‐flavored bars were preferred over fruit‐flavored bars. Attributes connected to chocolate flavor positively influenced consumer overall likings on the global and individual consumer levels. Textural attributes affected liking only on the individual level. To fully capture the importance of sensory attributes on consumer preference, the use of GPLSR in conjunction with IPLSR is recommended.     

From intention to action: Predicting purchase behavior with consumers’ product expectations and perceptions,and their individual properties

The association between purchase intention ratings and actual purchase behavior of two spoonable dairy (snack) products was examined. Particular attention was in two phases of the buying process: 1) expectation based on brand and package picture that is simulating in-store experience (before trying the product), and 2) perception based on branded tasting that is simulating in-home experience (after tasting the product), and how these ratings predict purchase behavior. Another attention was in examining which factors on individual level and product type level explain whether the intention leads to actual purchase behavior or not. Two groups of consumers evaluated either three natural yogurts (n = 105) or three flavored protein quarks (n = 107). The study consisted of three surveys and one evaluation session. In the first survey, the respondents rated the samples based on brand and package picture of the product for expected of purchase intention. In the tasting session, the respondents rated the purchase intention after tasting with the brand and package information. In the last two surveys, respondents reported which products they had bought during the last two weeks. These surveys were sent biweekly after the tasting session. Purchase intention based on both expectation and perception are significant factors in predicting purchase behavior in both product types. Factors differentiating buying and non-buying intenders of spoonable dairy snacks are mostly product type dependent. Being a user of the brand increases the proportion of intentions leading to actual buying in a staple product (natural yogurt). Heavy usage of the product increases the probability of consumers’ intentions to lead to actual buying in a personal use type of product (flavored protein quark).     

Survival Analysis Applied to Sensory Shelf Life of Yogurts–II: Spanish Formulations

Sensory shelf lives of commercial Spanish yogurts stored at 10 °C were studied. Yogurts were strawberry flavored and differed in fat content (free and whole‐fat) and consistency (stirred and set‐style). Yogurts were tested between 0 and 90 d of storage by consumers who expressed acceptance or rejection of each sample and measured overall and attribute acceptability on a 9‐point hedonic scale. Survival analysis statistics were used to estimate sensory shelf lives. Considering 25% of consumers rejecting the product, shelf lives varied from 38 to 69 d, depending on the composition, so if useful life were to be established using sensory criteria, a single shelf life for yogurt would not appear to be very appropriate. A log‐linear model and a direct quantile comparison formula were introduced to analyze the effect of formulation on rejection time distributions and shelf life values, respectively. Fat‐free yogurts had shorter shelf lives than whole‐fat yogurts. Acceptability of yogurts measured on a 9‐point hedonic scale varied less than percentage rejection over the storage times.     

A note on formulae for CMH statistics for JAR data

Cochran–Mantel–Haenszel (CMH) test statistics can be used to compare products rated on JAR ‘just about right’ scales and for similar categorical data. In this note we consider the case of paired or related data. The simplified statistics we give allow ‘by hand’ calculation when the data set is small. We also give an R package for larger data sets or for when the user is not interested in ‘by hand’ calculation.     

Are consumer profiling techniques equivalent for some product categories? The case of orange‐flavoured powdered drinks

Taking into account consumers’ perception in new product development has been regarded as a key strategy to developing more successful food products. In this context, consumer profiling techniques have increased their popularity in the last decade. The aim of the present work was to compare four consumer profiling techniques (sorting, projective mapping, intensity scales and check‐all‐that‐apply questions) in orange‐flavoured powdered juice drinks. A consumer study was carried out with 200 regular consumers of the category, which were divided into four groups. Each group used a different methodology to evaluate seven commercial powdered drinks. After completing the task consumers were asked to rate its difficulty on a nine‐point hedonic scale. Results showed that the four evaluated methodologies were able to identify differences in consumers’ perception of the sensory characteristics of the drinks, providing similar information. However, the application of CATA questions and intensity scales was regarded as easier for consumers. Advantages and disadvantages of the evaluated methodologies are discussed.     

The concurrent use of JAR and CATA questions in hedonic scaling is unlikely to cause hedonic bias,but may increase product discrimination

The concurrent use of CATA questions (check-all-that-apply) with hedonic scaling in product research with consumers has gained acceptance in recent years. However, CATA questions do not enable product developers to identify consumers’ preferred intensity of a sensory attribute directly, and for this reason just-about-right (JAR) questions are sometimes used together with questions that quantify attribute presence and/or intensity. Using JAR questions, consumers have to describe each of the samples in terms of each specific attribute, typically: 1 = ‘Not enough…’, 3 = ‘Just about right’, and 5 = ‘Much too…’. Past research has suggested that co-elicitation of hedonic and JAR responses bias the hedonic data. This undesired effect could extend to the case where JAR questions are used concurrently with hedonic and CATA questions. In seven studies (N = 762) across seven product categories no such evidence was found. Additionally, there was some evidence pointing to an increase in product discrimination based on hedonic and CATA responses. Preliminary data indicated that the inclusion of JAR questions in product tests also eliciting hedonic and CATA responses did not negatively affect consumers’ perception of the task, which, on average, was still regarded as easy and not tedious. Future research is required to validate the findings across more varied experimental settings.     

Impact of Label Information on Consumer Assessment of Soy-enhanced Tomato Juice

ABSTRACT: The impact of label information on the liking and closeness to ideal of tomato juice beverages was examined by having 100 judges assess 3 tomato juice beverages (Campbell's tomato juice, V8 juice, and an experimental tomato juice enhanced with soy) either with or without labeling information. Judges rated overall liking of each product and then rated appropriateness of various attributes (saltiness, tomato flavor, thickness, texture, red color, orange color, and brown color) on 5-point just-right scales. Only half of the judges were presented with product-related label information during evaluation. Overall liking scores were analyzed using repeated-measures ANOVA, whereas different attribute ratings were analyzed using Thurstonian Ideal Point modeling and Chi-square. Product-associated label information did not significantly alter overall liking ratings ( P > 0.05), although a significant difference in liking was found between products ( P < 0.05). Similarly, the label information did not impact comparison of product attribute levels to ideal attribute levels. Both V8 and Campbell's were significantly different from the ideal for 3 of the attributes ( P < 0.05). For the soy-enhanced tomato juice, all 7 attributes were significantly different from the ideal ( P < 0.05). In this instance, labeling information had no notable impact on assessments.     

Effect of storage parameters on freeze‐dried kefir grains

The purpose of this study was to use freeze‐drying to preserve microbial activity while extending the shelf life of kefir grains and to determine the best storage temperature. Freeze‐dried kefir grains were lyophilised and were later stored in a multilayer plastic film with a moisture barrier for 90 days at varying temperatures. Microbial activity continued until the 60^th day of storage at 4 °C. PCR analysis was performed to determine Lactobacillus kefiranofaciens as an indicator kefir micro‐organism. It was concluded that the conservation of kefir grains by freeze‐drying protects the natural embedded microbiota; therefore, both the shelf life of kefir grains and the consumption of natural kefir increase.     

Rejection Thresholds in Solid Chocolate‐Flavored Compound Coating

Abstract: Classical detection thresholds do not predict liking, as they focus on the presence or absence of a sensation. Recently however, Prescott and colleagues described a new method, the rejection threshold, where a series of forced choice preference tasks are used to generate a dose‐response function to determine hedonically acceptable concentrations. That is, how much is too much? To date, this approach has been used exclusively in liquid foods. Here, we determined group rejection thresholds in solid chocolate‐flavored compound coating for bitterness. The influences of self‐identified preferences for milk or dark chocolate, as well as eating style (chewers compared to melters) on rejection thresholds were investigated. Stimuli included milk chocolate‐flavored compound coating spiked with increasing amounts of sucrose octaacetate, a bitter and generally recognized as safe additive. Paired preference tests (blank compared to spike) were used to determine the proportion of the group that preferred the blank. Across pairs, spiked samples were presented in ascending concentration. We were able to quantify and compare differences between 2 self‐identified market segments. The rejection threshold for the dark chocolate preferring group was significantly higher than the milk chocolate preferring group (P= 0.01). Conversely, eating style did not affect group rejection thresholds (P= 0.14), although this may reflect the amount of chocolate given to participants. Additionally, there was no association between chocolate preference and eating style (P= 0.36). Present work supports the contention that this method can be used to examine preferences within specific market segments and potentially individual differences as they relate to ingestive behavior. Practical Application: This work makes use of the rejection threshold method to study market segmentation, extending its use to solid foods. We believe this method has broad applicability to the sensory specialist and product developer by providing a process to identify how much is too much when formulating products, even in the context of specific market segments. We illustrate this in solid chocolate‐flavored compound coating, identifying substantial differences in the amount of acceptable bitterness in those who prefer milk chocolate compared to dark chocolate. This method provides a direct means to answer the question of how much is too much.     

开菲尔微生态的研究进展

开菲尔粒是传统的开菲尔发酵剂,它的结构组成菌特别复杂,所以一直是人们研究的热点。本文主要介绍了开菲尔粒的组成、结构、菌相及其分布、相互关系、保存,开菲尔微生态制品的保健功能及其加工工艺,并对开菲尔粒的研制现状与展望进行了综述。     

Quality Evaluation of Chile-flavored, Jerky-type Extruded Products from Meat and Potato Flour

Extruded, jerky-type products prepared from potato flour combined with either partially defatted chopped beef (PDCB), mechanically separated chicken (MSC) or chicken thigh meat (C) and flavored with three levels of Chile powder were evaluated by instruments and sensory methods. Meaty aroma was more intense than potato or Chile aromas in all samples. MSC product tended to have the darkest color. Shear strength, tensile strength and sensory analyses indicated Chile powder may be a binding agent, resulting in harder texture, particularly in C products. Meaty and black pepper were dominant flavor characteristics detected by sensory panelists. Overall, PDCB product containing 0.5% Chile was rated most desirable.     

The quest for the ideal product: Comparing different methods and approaches

This study compares three widely used methods for product optimisation or development: the just about right (JAR) method, the conventional method and a variant thereof. Three independent samples of respondents evaluated five variations of natural yoghurt according to one of the three methods. Theoretically, JAR and the variant method differ in how they approach attribute deviations from ideal (directly versus indirectly). The fundamental difference between the conventional and the variant method are the ideal points (calculated versus measured directly). Overall, we found that the methods yield similar orders of ideal points despite their methodological dissimilarities. However, in terms of suggested directions for product improvement, substantial differences exist which suggests that statistical criteria are an insufficient basis for these decisions which needs to be complemented by managerial judgment on the size of the deviation.     

一种新型开菲尔风味复合发酵剂的研制

为研制一款新型的风味突出、理化性质稳定的开菲尔风味复合发酵剂,该研究从源自中国新疆的10种开菲粒中分离获得51株乳酸菌、22株酵母菌。51株乳酸菌中,3株乳酸菌的产香能力和蛋白分解能力突出,单菌发酵乳的全质构特性最稳定。其中,开菲尔乳杆菌MLK5的乙醛质量浓度为15.82 mg/L、双乙酰质量浓度为3.99 mg/L、氨基氮质量浓度为597.09 mg/L,干酪乳杆菌SLC1的乙醛质量浓度为20.02 mg/L、双乙酰质量浓度为4.69 mg/L、氨基氮质量浓度为684.92 mg/L,肠膜明串珠菌NLM2的乙醛质量浓度为18.01 mg/L、双乙酰质量浓度为4.44 mg/L、氨基氮质量浓度为600.58 mg/L。22株酵母菌中,马克思克鲁维酵母菌菌株FY1的乙醇产量适宜,遗传稳定性好,乳糖利用率最高为56.56%。最终确定,发酵剂中最佳比例为乳酸菌:酵母菌=5:1,3株乳酸菌间最优例为肠膜明串珠菌:开菲尔乳杆菌:干酪乳杆菌为1:2:1。复合发酵乳的凝乳时间为6.0 h、酸度为84.65 ºT、持水力为62.31%、乙醇体积分数为0.53%、乳酸菌活菌数为3.89×109 CFU/mL、酵母菌活菌数为4.61×106 CFU/mL、感官评分为89.21,与开菲尔粒发酵乳的各项指标类似。而复合发酵乳中的挥发性风味物质间构成和谐,更易于消费者接受。上述研究结果,有助于稳定和简化开菲尔的工业生产,为开发不同风味酸乳产品提供参考。     

DISTINGUISHING ACTIONABLE VERSUS INACTIONABLE ATTRIBUTES

This paper distinguishes between two classes of product attributes, actionable attributes and inactionable ones. Actionable attributes are those which (a) can be optimized by varying the types and levels of ingredients in a product and (b) probably reflect true sensory orperceptual responses to products. Examples are sweetness, fragrance, softness, and the like. Inactionable attributes are those which cannot be optimized in this way, no matter what type or level of ingredient is varied. These inactionable attributes may reflect alternate ways of saying “degree of liking”. Actionable attributes can be distinguished from inactionable ones by contrasting the attribute profile of existingproducts versus ideal products, or versus concepts when products, concepts and ideals are profiled on the same attributes and scales. This must be done in the same study, however.