Number of consumers necessary for survival analysis estimations based on each consumer evaluating a single sample

The objective of the present work was to use simulation studies to estimate the number of consumers necessary to obtain valid estimations from survival analysis calculations where each consumer evaluates a single sample. Based on previous studies a Weibull model was assumed for the lifetime distribution with a shape parameter σ between 0.17 and 0.71. Simulations were calculated supposing shelf-life values in the middle range of an adimensional time scale. Graphs to estimate N under different scenarios are presented. Considering the average σ, an alpha value (Type I error) of 5%, a beta value (Type II error) of 20%, the shelf-life to be in the middle of the studied time range and a difference between the true shelf-life and the estimated shelf-life of 0.5 on a 0-6 time scale, gave an N value of 300 consumers for this particular set of parameters. As 6 time values were considered this means 50 consumers for each one of the storage times. In the present study time was taken as the reference variable, however the same calculations and conclusions are valid for other variables of interest, such as concentration or temperature, that replace the time variable in survival analysis calculations.     

Number of consumers necessary for sensory acceptability tests

Basic concepts necessary to estimate the number of consumers necessary for sensory acceptability studies (N), variability data on previous consumer studies and estimations of N for different values of Type I and Type II errors are presented. The standard error of the experiment, reported as the root mean square error from the analysis of variance, was similar over 108 reported studies conducted in five countries over a wide range of food products. This allowed estimating the number of consumers necessary for future studies. These estimations are presented in a table. Considering the average standard error, an alpha value (Type I error) of 5%, a beta value (Type II error) of 10% and a difference between sample means of 10% of the sensory scale, gave an N value of 112 consumers for this particular set of parameters.     

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.     

Survival Analysis Applied to Sensory Shelf Life of Yogurts–I: Argentine Formulations

:Sensory shelf lives of Argentine commercial stirred yogurts of different compositions stored at 10 °C were studied. Variations were as follows: fat‐free and whole‐fat, and vanilla and strawberry flavors. Yogurts were tested between 0 and 84 d of storage by consumers who expressed their acceptance or rejection of each sample; yogurts also were measured overall, as well as their attribute acceptability, with a hedonic scale. Survival analysis statistics were used to estimate shelf lives. Considering 25% of consumers rejecting the product, shelf lives were between 28 and 41 d; thus, a unique shelf life for this product does not seem reasonable. 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. Overall, fat‐free yogurts had lower shelf lives than whole‐fat yogurts.     

Viability of total phenol index value as quality marker of sparkling wines, “cavas”

To evaluate the viability of the A280 value for monitoring the development of cava sparkling wine during its ageing in contact with lees and its commercial shelf life, an accelerated test was applied to four types of sparkling wines obtained at industrial scale. All cava types were stored under oxygen and carbon dioxide conditions at 37 °C for 13 weeks. During the accelerated test, a positive relationship between absorbance at 280 nm (A280) and time was observed, while the main phenolic compounds decreased even under nonoxidative conditions. The increase in the phenol index value corresponded (p < 0.01) to an increase in a colourless compound. Both increases occurred mainly under nonoxidative conditions. This compound is a tentatively identified polyhydroxylate structure with a λ_max 284 nm and an accurate mass of 178.0398, which corresponds to the molecular formula, C₆H₁₀O₆. The present study found that sugars are the origin of this compound and play an important role in A280 increase under reductive conditions. The value of A280 could be a simple marker for monitoring the quality of the evolution of sparkling wine during its ageing in contact with lees and its commercial shelf life.     

Sourdough Technology—A Traditional Way for Wholesome Foods: A Review

Abstract: In the present era, consumers wish to have a wide range of foods that are nutritious and flavorful and have long shelf life without added preservatives. Sourdough is an important modern fermentation of cereal flours and water based upon an earlier spontaneous process. The sourdough microflora is dominated by lactic acid bacteria and, along with yeast, they play a key role in the fermentation of bread dough. Factors that affect the quality of sourdough are dough yield, temperature, type of starter culture, acidity of the medium, and the substrate. Sourdough is classified into 3 types (Types I, II, and III); the most widely used for commercial production is Type III. The sourdough fermentation has a number of beneficial effects that include prolonged shelf life, accelerated volume gain, delayed staling, improved bread flavor, and good nutritional value. Sourdough also improves sensory characteristics such as loaf volume, evenness of baking, color, aroma, taste, and texture of breads. Sourdough has been reported to contribute to extended shelf life by inhibiting spoilage bacteria and mold growth.     

预包装食品营养标签中钠的标示问题分析

矿物质钠作为核心营养素之一,在我国GB 28050-2011《预包装食品营养标签通则》中已被列为强制标示的营养成分。本文通过阐述预包装食品营养标签中钠的标示要求,分析钠的标示常见问题及实例;同时对比GB 13432-2013《预包装特殊膳食用食品标签》与GB 28050-2011中钠的允许误差范围判定区别;总结钠的营养标签标示易错点及在保质期内钠含量的实测值超出允许误差范围所需关注情况。本研究有助于切实维护消费者利益,正确指导生产企业规范合理标示,同时建议进一步研究监管上如何科学合理评判婴幼儿特殊膳食食品标签钠的标识合规性。     

Growth ofListeria monocytogeneson sliced cooked meat products

During the shelf life (4–6 weeks) of artificially contaminated sliced cooked meat products such as luncheon meat, ham and chicken breast, the growth ofListeria monocytogenesunder vacuum was similar to the growth under modified atmosphere (30% CO₂/70% N₂) packaged products. The presence of competitors (lactobacilli), even in concentrations 100 times those ofL. monocytogenes, only slightly inhibited growth of this pathogen. At the end of the shelf life levels were still 10⁷cfug⁻¹. Due to the lower initial contamination, levels in naturally contaminated products were about 10⁴cfug⁻¹. To prevent outgrowth ofL. monocytogenesto such high levels it is necessary to prevent recontamination during slicing and packaging, and to shorten the rather long shelf life of these products. Due to the low pH of fermented sausage (saveloy) and (raw) Coburger ham the numbers ofL. monocytogenesdecreased below the detection level.     

Effect of modified atmosphere packaging on the growth of spoilage microorganisms and Listeria monocytogenes on fresh cheese

Queso Fresco has a limited shelf life and has been shown to support the rapid growth of Listeria monocytogenes during refrigerated storage. In addition to improving quality and extending shelf life, modified atmosphere packaging (MAP) has been used to control the growth of pathogenic microorganisms in foods. The objectives of this study were to determine the effects of MAP conditions on the survival and growth of spoilage microorganisms and L. monocytogenes during storage of Queso Fresco manufactured without starter cultures. For L. monocytogenes experiments, cheeses were surface inoculated at ～4 log₁₀ cfu/g before packaging. Inoculated and uninoculated (shelf life experiments) cheeses were placed in 75-µm high-barrier pouches, packaged under 1 of 7 conditions including air, vacuum, or combinations of N₂ and CO₂ [100% N₂ (MAP1), 30% CO₂:70% N₂ (MAP2), 50% CO₂:50% N₂ (MAP3), or 70% CO₂:30% N₂ (MAP4), 100% CO₂ (MAP5)], and stored at 7°C. Samples were removed weekly through 35 d of storage. Listeria monocytogenes counts were determined for inoculated samples. Uninoculated samples were assayed for mesophilic and psychrotolerant counts, lactic acid bacteria, coliforms, and yeast and mold. In general, cheeses packaged under conditions consisting of higher contents of CO₂ had lower pH levels during storage compared with those stored in conditions with lower levels or no CO₂ at all. Similarly, the antimicrobial efficacy of MAP in controlling spoilage microorganisms increased with increasing CO₂ content, whereas conditions consisting of 100% N₂, vacuum, or air were less effective. Mean L. monocytogenes counts remained near inoculation levels for all treatments at d 1 but increased ～2 log₁₀ cfu/g on cheeses packaged in air, vacuum, and 100% N₂ (MAP1) conditions at d 7 and an additional ～1.5 log₁₀ cfu/g at d 14 where they remained through 35 d. In contrast, treatments consisting of 70% CO₂ (MAP4) and 100% CO₂ (MAP5) limited increases in mean L. monocytogenes counts to <1 log₁₀ cfu/g through 14 d and ～1.5 log₁₀ cfu/g by d 21. Mean L. monocytogenes counts increased to levels significantly higher than inoculation (d 0) on cheeses stored in MAP2 and MAP3 on d 21, on d 28 for MAP4, and on d 35 for cheeses stored under MAP5 conditions. Overall, significant treatment × time interactions were observed between air, vacuum, and MAP1 when each was compared with MAP2, MAP3, MAP4, and MAP5. These data demonstrate that packaging fresh cheese under modified atmospheres containing CO₂ may be a promising approach to extend shelf life while limiting L. monocytogenes growth during cold storage.     

West African sorghum beer fermented with Lactobacillus delbrueckii and Saccharomyces cerevisiae: shelf‐life and consumer acceptance

The fermentation profiles, shelf‐life and consumer acceptance of traditional West African sour sorghum beer (pito) fermented with pure commercial starter cultures of lactic acid bacteria (L. delbrueckii) and yeast (Saccharomyces cerevisiae) were evaluated. The beers from this ‘pure culture’ approach were compared with the spontaneous fermentation of pito wort. Lactic acid formation, pH change and extract utilisation were monitored during fermentation. Lactic acid content was used as a measure of sourness to establish the spoilage level of over‐sourness. Further, regression models relating sourness to the time the drink was kept were used to predict the shelf‐life. Consumer acceptance of the product was evaluated using a novel nine‐point hedonic scale. The pure culture and traditionally fermented beers followed similar lactic acid and fermentation profiles but strain‐specific differences were observed. Similar levels of pH, lactic acid level and extract utilisation were achieved. An improvement in shelf‐life of two days was found over traditionally fermented pito. There was no statistical difference between the two pito products for overall liking and taste. However, there was a preference for the aroma of the pure culture pito. It is suggested that the use of pure cultures will facilitate the scale‐up of pito production. © 2019 The Institute of Brewing & Distilling     

Chemical composition and antibacterial activity of Laurus nobilis essential oil towards foodborne pathogens and its application in fresh Tuscan sausage stored at 7 °C

The presence of foodborne pathogens in fresh Tuscan sausage has been reported and these contaminations pose a potential risk to consumers. The objective of the present study was to evaluate the antimicrobial activity of bay leaf essential oil (EO) in vitro and in fresh Tuscan sausage stored at 7 °C for 14 d. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against foodborne pathogens were determined in vitro. The lowest MIC and MBC were found for Escherichia coli (MIC = MBC = 2.5 g/L) and Yersinia enterocolitica (MIC = 1.25 g/L, MBC = 2.5 g/L). Fresh Tuscan sausages were treated with bay leaf EO at 0.05 g/100 g or 0.1 g/100 g and their shelf life was compared to a non-treated control. All groups presented low levels of rancidity (TBARS < 0.5 mg MDA/kg). The EO was able to reduce the population of total coliforms (2.8 log CFU/g) and to extend the product shelf life for two days. Although the presence of the EO affected the sensory characteristics of the sausage, it was considered acceptable by consumers at both concentrations tested. Overall, the results of this study indicate that bay leaf essential oil can be applied in fresh Tuscan sausage to improve its safety and shelf life.     

Combined effect of active coating and modified atmosphere packaging on prolonging the shelf life of low-moisture Mozzarella cheese

In this work, the effect of active coating on the shelf life of low-moisture Mozzarella cheese packaged in air and modified atmosphere (MAP) was studied. The active coating was based on sodium alginate (2%, wt/vol) and potassium sorbate (1%, wt/vol). The MAP was made up of 75% CO₂ and 25% N₂ (MAP1), 25% CO₂ and 75% N₂ (MAP2), or 50% CO₂ and 50% N₂ (MAP3). The product quality decay was assessed by monitoring microbiological and sensory changes during storage at 4, 8, and 14°C. Results showed that the combination of active coating and MAP was able to improve the preservation of low-moisture Mozzarella cheese. Specifically, the shelf life increased up to 160 d for samples stored at 4°C, and 40 and 11 d for those at 8 and 14°C, respectively. A faster quality decay for untreated samples packaged in air was observed. In particular, the Pseudomonas spp. growth and the appearance of molds were responsible for product unacceptability. The combination of active coating and MAP represents a strategic solution to prolong the shelf life of low-moisture Mozzarella cheese and to ensure the safety of the product under thermal abuse conditions.     

Shelf Life Determination of Sliced Portuguese Traditional Blood Sausage—Morcela de Arroz de Monchique through Microbiological Challenge and Consumer Test

Morcela de Arroz (MA) is a ready‐to‐eat blood and rice cooked sausage produced with pork, blood, rice, and seasonings, stuffed in natural casing and cooked above 90 °C/30 min. It is commercialized whole, not packed, with a restricted shelf life (1 wk/0 to 5 °C). The objective of this work was to establish sliced MA shelf life considering both the behavior of L. monocytogenes through a microbiological challenge test (MCT) and the consumer acceptability of MA stored: vacuum packed (VP), modified atmosphere packed (MAP: 80% CO₂/20% N₂), and aerobic packed (AP). The MCT was conducted inoculating ±3 log CFU/g of L. monocytogenes cell suspension on the MA slices. Packaged samples were stored at 3 ± 1 °C and 7 ± 1 °C until 20 d. At 3 ± 1 °C, L. monocytogenes behavior was not affected by packaging or storage time. At 7 ± 1 °C, the pathogen increased nearly 1 log CFU/g in the first 4 d. L. monocytogenes populations in AP were higher (P < 0.05) than in MAP. The pathogen may grow to hazardous levels in the 1st days if a temperature abuse occurs. Considering the acceptability by the consumers, the shelf life of MA stored at 3 ± 1 °C was 4.4 d for AP, 8.1 d for VP, and 10.4 d for MAP. The sensory shelf life established based on sensory spoilage is shorter than the shelf life to maintain the population of L. monocytogenes in safe levels.     

Survival Analysis Applied to Sensory Shelf Life of Foods

ABSTRACT: Survival analysis concepts to be used in sensory shelf life studies were introduced, together with the equations necessary for calculations. The survival function was defined as the probability of consumers accepting a product beyond a certain storage time. Censoring phenomena, a key concept in survival analysis, was defined and has been shown to occur in sensory shelf‐life data. Concepts and calculations were applied to a data set obtained from 50 consumers who each tasted seven yogurt samples with different storage times, answering “yes” or “no” to whether they would consume the samples. From this censored data set, nonparametric and parametric models were obtained that allowed shelf‐life estimations.     

Modelling the effect of temperature and water activity on the growth of Aspergillus parasiticus on irradiated Argentinian flint maize

A full factorially designed experiment including storage temperature (10, 20, 30 and 37 °C) and water activity (0.88, 0.92 and 0.96) was undertaken to study the growth of Aspergillus parasiticus in maize samples. Kinetic parameters such as specific growth rate (μ), lag phase duration and maximum logarithmic increase were determined by fitting the Modified Gompertz equation to the viable mould count data (N in CFU/g) as a function of time collected in twelve experiments. The average coefficient of determination (R²) was 0.987, being the mean standard deviation of the estimate of 0.216 in units of log₁₀N. In the practical range of 10-30 °C, the relationship of the three kinetic parameters with temperature was described by second order polynomial expressions, whose parameters, in turn, depended on water activity. The combined or full model i.e., the Modified Gompertz model with its parameters expressed as a function of temperature and water activity, was able to predict log₁₀N with an average percentage error of 4.3, so agreement with the experimental data was highly satisfactory.In a simulation exercise, the full model was able to predict the viable mould count, given an initial value and grain temperature and water activity histories, with promising results for maize storage.     

Application of smart packaging for seafood: A comprehensive review

Nowadays, due to the changes in lifestyle and great interest of consumers in a healthy life, people have started increasing their seafood consumption. But due to their short shelf life, experts are looking for a new packaging called smart packaging (SMP) for seafood. There are different indicators/sensors in SMP; one of the effective indices is time–temperature, which can show consumers the best time of using seafood based on their shelf life and experienced temperature. Another one is radio-frequency identification (RFID) that is a transmission device that represents a separate form of the electronic information-based SMP systems. RFID does not belong to any of the categories of markers or sensors; it is an auto recognition system that applies cordless sensors to indicate segments and collect real-time information without manual interposition. This review covers the use of SMP in all marine foods, including fish, due to its high consumption and high content of polyunsaturated fatty acids, eicosapentaenoic acid (C20:5n-3) and docosahexaenoic acid (C22:6n-3), which are the considerable factors of n-3 polyunsaturated fatty acids for human.     

Extension of shelf life of pasteurized trim milk using ultraviolet treatment

The demand for minimally processed foods has increased in the last few years and gains high acceptability among consumers as it has better nutritional value than highly processed foods. Pasteurized milk is minimally processed and consumed largely for its fresh taste and higher nutritional value compared to ultrahigh temperature (UHT) and powdered milk. However, one of the constraints is its limited shelf life under refrigeration, as it cannot retain quality and safety for more than 14 days. Nonthermal technologies can extend the shelf life of milk while using low energy. Ultraviolet (UV-C) is well known to inactivate spores as well as vegetative cells. In this study, it was shown that 2.64 J/ml of UV-C treatment applied on pasteurized trim milk can extend shelf life up to 53 days under refrigeration. This finding was also supported by the inactivation of 3.40 ± 0.14 log of thermoresistant Geobacillus stearothermophilus spores (ATCC 7953) in UHT (or sterilized) trim milk with similar UV-C operating conditions. Therefore, microbial study together with physicochemical properties demonstrated that pasteurization followed by UV-C can enhance the shelf life of trim milk considerably.     

A brief note on thermoluminescence analysis of photosystem II and lipid peroxidation during the shelf life of ready-to-use rocket (Diplotaxis tenuifolia L.)

The quality of leafy vegetables has to be guaranteed for consumers over the whole postharvest period, usually limited to 5–7 days. The analyses to evaluate the quality of vegetables are very time- and resource consuming, so the use of qualitative markers can be much useful. The aim of this work was to evaluate the use of thermoluminescence (TL) parameters as qualitative markers of fresh-cut leafy vegetables during the shelf life. TL is a technique consisting of a cooling, followed by the progressive warming, of a preilluminated sample to reveal the different types of charge pairs as successive emission bands, which are resolved better than the corresponding decay phases recorded at constant temperature. Experiments were performed on rocket (Diplotaxis tenuifolia L.) stored at 2 °C for 7 days. During storage, several changes in TL glow curves were found. The position of the peaks showed a shift to higher temperature. The area of the peaks, relating to the photosystem II (20–65 °C), grew up lightly; whereas in the temperature range that detects lipidic peroxidation (65–140 °C), the TL emission became more than twice. These changes demonstrated that, during the shelf life, a progressive destabilization of PSII centres occurred and that lipid peroxidation products were accumulated in membranes. TL could be used to estimate the damages immediately after as well as during the storage period. This is the first time that TL was used to evaluate the quality of fresh-cut vegetables products during the shelf life.     

Agar-immobilized basil–lactic acid bacteria bioproducts as goat milk taste-masking agents and natural preservatives for the production of unripened goat cheese

Goat milk cheeses have become popular recently; however, many consumers do not choose these products because they have specific sensory properties that are not acceptable to all consumers and the shelf life of the cheese is short. The concept of this work was to increase overall acceptability and shelf life of unripened goat milk cheese by using Ocimum basilicum and lactic acid bacteria (Lactobacillus plantarum LUHS135, Lactobacillus paracasei LUHS244, Pediococcus pentosaceus LUHS100, Pediococcus acidilactici LUHS29, and Lactobacillus brevis LUHS140) bioproducts (basil-LAB) immobilized in agar. A basil-LAB bioproduct could be a promising multifunctional ingredient for cheese manufacturing because it has a low pH, high LAB count, and high total phenolic compound content (after fermentation pH decreased by 25.4%, LAB count averaged 7.2 log₁₀ cfu/g, and total phenolic compound content increased by 30.9%). Use of different LAB in the preparation of basil-LAB bioproducts had a significant influence on cheese pH and hardness, and compared with cheese samples prepared with nonfermented basil, cheese samples prepared with basil-LAB bioproducts had, on average, higher pH (by 2.6%) and lower hardness (by 36.0%), similar to the control cheese (without basil). Overall acceptability of cheese was significantly influenced by the basil-LAB bioproduct immobilization process; in all cases, cheese samples prepared with fermented and immobilized basil-LAB bioproduct had better acceptability (5 points). After 120 h of storage, cheese samples prepared with basil-LAB bioproducts fermented with LUHS135, LUHS244 and LUHS140, no enterobacteria were found, and we detected strong negative and moderate negative correlations, respectively, of LAB count with enterobacteria count and yeast/mold count (r = ?0.7939 and r = ?0.4495, respectively). Finally, immobilization increased LAB viability in fresh goat milk cheese, which led to a reduction in enterobacteria and mold/yeast contamination during storage and an increase in overall acceptability compared with nonimmobilized basil-LAB. Therefore, basil-LAB bioproducts fermented with LUHS135, LUHS244, and LUHS140 strains can be recommended for preparing fresh goat milk cheese with extended shelf life and high acceptability.