Organoleptic Deterioration Research Articles

The active kappa-carrageenan coating and oxygen absorber packaging for the preservation of chilled rainbow trout fillets

The objective of the current research was to evaluate the effects of incorporating kappa-carrageenan (KCA) coating with dill essential oil (DEO), in conjunction with oxygen absorber (OA) packaging, on the quality attributes of rainbow trout fillets throughout a 20-day period of refrigerated storage. The administered treatments included OA, KCA + OA, KCA + DEO, KCA + DEO + OA, and control. Treating the trout fillets with DEO-loaded coating and/or using OA packaging was found to be more effective in restricting the growth of total mesophilic and psychrotrophic bacteria, Enterobacteriaceae, and lactic acid bacteria. The aforementioned treatments were more efficient in slowing down the rate of increase in pH, total volatile nitrogen, conjugated dienes, thiobarbituric acid reactive substances, protein carbonyls, electric conductivity, and organoleptic deterioration in the trout fillets. Notably, the most effective treatment in this context was KCA + DEO + OA. The shelf-life of trout fillets was established through the assessment of multiple parameters. It was determined to be 4 days in both the control and KCA groups, 8 days in the OA and KCA + OA groups, 16 days in the KCA + DEO group, and a minimum of 20 days in the KCA + DEO + OA group. Consequently, our recommendation is to apply an active coating based on KCA, incorporating DEO in conjunction with OA packaging, for the preservation of fish fillets stored in refrigeration.

Development of Chinese-Style Sausage Enriched with Djulis (Chenopodium formosanum Koidz) Using Taguchi Method: Applying Modern Optimization to Indigenous People's Traditional Food.

Djulis (Taiwanese quinoa) has gained popularity among researchers due to its biological characteristics and rich nutritional value. Incorporating Djulis is expected to enhance the sausage's texture, flavor, and storage stability due to the presence of antioxidants and nutritional components. However, limited studies focus on product development based on this emerging health-promoting ingredient in the food industry. This study aims to develop Chinese-style sausage enriched with Djulis using the Taguchi L9(34) orthogonal matrix methodology and evaluate the influence of four factors, including un-hulled to hulled Djulis ratios of 0, 50, 100% (A), backfat-to-lean meat ratios of 0/100, 30/70, 50/50% (B), cooking temperature of 55, 75, 95 °C (C), and nitrite content of 0.03, 0.05, 0.07 g/kg (D) on products' sensory and physicochemical properties. The optimal Taguchi formulation was then verified and compared with conventionally formulated sausage (original sausage) in terms of hardness, springiness, gumminess, CIE color values, and peroxide value (POV). The optimal formulation was A3B2C2D3, which consisted of 16.8% hulled Djulis, 30/70 backfat-to-lean meat ratio, 75 °C cooking temperature, and 0.03 g/kg nitrite content. The most influential independent parameters were identified as B > A > C > D, placing Djulis incorporation as the first runner-up, just after the backfat-to-lean meat ratio. Optimized condition verification identified the Signal-to-Noise ratio (S/N) of 16.63. Comparing the optimized Djulis-enriched sample and the original sausage indicated similar CIE L*, a*, b*, hardness, and springiness but different gumminess according to Texture Profile Analysis (TPA). The Djulis-enriched sausage at the optimized formulation had a significantly lower POV compared to the control sample (4.65 vs. 9.64 meq/kg), which was found to be correlated with Djulis antioxidant effects with 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical antioxidant activity of 62.37%. This suggests that Djulis effectively mitigates sausage organoleptic deterioration. Djulis sausage, with natural antioxidants and reduced fat content, could cater to consumer preferences and enhance the market for the food industry and indigenous farmers.

Microbial Control by High Pressure Processing for Shelf-Life Extension of Packed Meat Products in the Cold Chain: Modeling and Case Studies

Vacuum packed Bratwurst type cooked sausages and sliced or cubed meat products that have limited shelf-life of few days in chilled storage were HP processed (5 min, 600 MPa, 25 °C) and stored at different temperatures (0–15 °C). Color, texture, and microbiological and sensory evaluation were kinetically studied for control and HP treated samples. HP treatment did not alter the color and texture of the treated samples when compared to untreated ones. Lactic acid bacteria were found to be the main spoilage index. The rates of microbiological and organoleptic deterioration were estimated, and their temperature dependence was modeled by the Arrhenius equation. An increase of their shelf life of five to eight times was estimated, compared to untreated ones. A sensory survey on HP treated cooked ham showed that the consumers could not distinguish differences between control and processed samples immediately after processing. Obtained results were used along with appropriate tools relevant to cold chain management to demonstrate that HP treated products are less perishable compared to control ones, allowing for short exposure to temperature deviations during transportation and storage. This has a positive impact on the reduction of the frequency of spoiled products before consumption, acting as a useful tool for the meat product’s loss and waste reduction.

Effects of Chitosan-Coated Paperboard Trays on the Botrytis cinerea Formation and Sensory Quality of Bilberries (Vaccinium myrtillus L.) and Redcurrants (Ribes rubrum L.)

ABSTRACTComparison of a chitosan-coated food contact material (active packaging) against the standard is carried out in this study. The shelf life of bilberries and redcurrants has been assessed, using visual inspection. Berries passed a professional sensory assessment on organoleptic deterioration. The berries were stored on consumer/retail-orientated standards to achieve a valid assessment on shelf-life impact. An increased shelf life can be achieved between 2 and 4 days, using 2% chitosan-coated food contact material.

β-Caryophyllene-rich pepper essential oils suppress spoilage activity of Pseudomonas fluorescens KM06 in fresh-cut lettuce

Pseudomonas fluorescens are able to cause the biodeterioration process of fresh-cut lettuce via the indole-3-acetic acid (IAA)-dependent type III secretion system (TTSS). The application of pepper EOs of proven of anti-IAA and anti-TTSS activities into salad dressing can reduce the organoleptic deterioration of fresh-cut leafy vegetables during storage. In this work, the influence of black and white pepper EOs on IAA production and on TTSS gene expression in P. fluorescens KM06 was examined. The black and white pepper EOs and β-caryophyllene at concentrations below the sub-MICs altered (i.e., 78%, 94%, and 90%, respectively) the IAA production in a 72 h old culture of P. fluorescens KM06. All the test agents significantly reduced the mRNA levels of the TTSS gene (−0.106, −0.428, and −0.448 for black pepper EO, white pepper EO and β-caryophyllene, respectively) (p < 0.05). In model in situ experiments, the supplementation of the salad dressing with sub-MIC doses of β-caryophyllene-rich white and black pepper EOs also markedly inhibited bacterial IAA production (by 81% and 73%, respectively) and the IAA-related TTSS gene expression (by −0.880 and −0.680, respectively) (p < 0.05). β-Caryophyllene-rich pepper EO seems to be a promising candidate to minimize or arrest the organoleptic deterioration of lettuce salad.

Effect of storage temperature and osmotic pre-treatment with alternative solutes on the shelf-life of gilthead seabream (Sparus aurata) fillets

The objective of the study was the kinetic modelling of the shelf-life of osmotically pre-treated fish during refrigerated and super-chilled storage. Fresh gilthead seabream (Sparus aurata) fillets were treated for 0–360 min at 15 °C in osmotic solutions 50:5 high dextrose equivalent maltodextrin:NaCl/100 g (HDM), 40:10:5 HDM:trehalose:NaCl/100 g (HDM + treh) and 40:10:5 HDM:glucosamine:NaCl/100 g (HDM + gluc). Water loss, solid gain, salt content and water activity were monitored throughout treatment. Slices untreated and osmotically pre-treated for 45 min were aerobically packed and stored isothermally at 15, 10, 5, 2.5, 0, −1 and −3 °C. Quality assessment was based on microbial growth (total viable count, Pseudomonas spp., Brochothrix thermosphacta, Enterobacteriaceae spp., H2S-producing bacteria, lactic acid bacteria, yeasts and moulds), total volatile nitrogen (TVB-N), lipid oxidation (TBARs) and sensory scoring. Quality indices were kinetically modelled and temperature dependence of quality loss rates was modelled by Ratkowsky equation.Osmotic pre-treatment led to significant shelf-life extension of fillets, in terms of microbial growth, chemical changes and organoleptic deterioration. The pre-treatment with the alternative solutes led to depression of the freezing point (−1.8, −2.6, −3.2 and −3.5 °C for the untreated samples and the osmotically pre-treated with HDM, HDM + treh and HDM + gluc, respectively). TVB-N values were higher in untreated samples, followed by osmotically treated fillets, mainly at higher storage temperatures (i.e. 10 and 15 °C). Based on the mathematical models for sensory evaluation scoring, the shelf-life was 12, 19, 22 and 22 days at 0 °C for untreated and osmotically pre-treated with HDM, HDM + treh and HDM + gluc fish slices, respectively, while the respective values at −3 °C were 21, 35, 38 and 38 days. The alternative solutes had no significant effect on the quality and shelf-life of pre-treated fish fillet during storage at refrigerated conditions.

Shelf-life extension of gilthead seabream fillets by osmotic treatment and antimicrobial agents

The objectives of the study were to evaluate the effect of selected antimicrobial agents on the shelf life of osmotically pretreated gilthead seabream and to establish reliable kinetic equations for shelf-life determination validated in dynamic conditions. Fresh gilthead seabream (Sparus aurata) fillets were osmotically treated with 50% high dextrose equivalent maltodextrin (HDM, DE 47) plus 5% NaCl and 0·5% carvacrol, 0·5% glucono-δ-lactone or 1% Citrox (commercial antimicrobial mix). Untreated and treated slices were aerobically packed and stored isothermally (0-15°C). Microbial growth and quality-related chemical indices were modelled as functions of temperature. Models were validated at dynamic storage conditions. Osmotic pretreatment with the use of antimicrobials led to significant shelf-life extension of fillets, in terms of microbial growth and organoleptic deterioration. The shelf life was 7 days for control samples at 5°C. The osmotic pretreatment with carvacrol, glucono-δ-lactone and Citrox allowed for shelf-life extension by 8, 10 and 5 days at 5°C, respectively. The results of the study show the potential of adding carvacrol, glucono-δ-lactone or Citrox in the osmotic solution to extend the shelf life and improve commercial value of chilled osmotically pretreated fish products. The developed models can be a reliable tool for predicting the shelf life of fresh or minimally processed gilthead seabream fillets in the real chill chain.

Filamentous Fungi in Drinking Water, Particularly in Relation to Biofilm Formation

The presence of filamentous fungi in drinking water has become an area worthy of investigation with various studies now being published. The problems associated with fungi include blockage of water pipes, organoleptic deterioration, pathogenic fungi and mycotoxins. Fungal biofilm formation is a less developed field of study. This paper updates the topic and introduces novel methods on fungal biofilm analysis, particularly from work based in Brazil. Further recommendations for standard methodology are provided.

Establish a Correlation between Storage Conditions and Period of Validity to Some Meat

Were carried out research on establishing correlations between storage conditions (temperature, time, humidity, organoleptic character, freshness) and validity period. Storage conditions such as humidity, shelf life, temperature and ventilation facilities, affecting the quality of meat products through organoleptic changes, physicochemical and microbiological they may suffer. Not observed when temperature, humidity and ventilation in storage space may occur a number of changes of organoleptic deterioration, including: the emergence of a sticky deposit on the surface of the membrane and mold colonies who often do not exceed the surface membrane, so do not enter in the product (lack of ventilation in hastening the emergence of these particular organoleptic changes). Also representative of physical changes occur as the product weight decrease due to water evaporation constitution. Organoleptic changes were pursued, physicochemical and microbiological two types of meat (sausage Rose and Parizer) during storage at 10-12°C, ie 4-6°C, relative humidity 7580% during validity. Correlating with the storage conditions during storage and organoleptic characters of dissolution, valid, based on investigations organoleptic, physico-chemical and microbiological, organoleptic changes occur is found after 10 days at Rose and sausage samples after six days in Parizer. These changes are more intense when stored at higher temperature and humidity values and appear to over 35 mg% ammonium nitrogen and amino nitrogen 250 mg%. Regardless of storage conditions, it appears that during this period in both products studied under physico-chemical aspect is noted a decrease in water content, fat, protein substances, collagen and starch, the amount of ammonia, amino nitrogen and salt growing. These changes are more intense if the product storage temperature and higher humidity. Correlating changes in the physico-chemical organoleptic and microbiological recommend maintaining the validity of 10 days for products semysmocked and 6 days for freshment. REFERENCES

포장두부의 가공공정에서 미생물 분석 및 안전성 평가

본 연구는 생산 후 3일 이내인 시판두부의 가공공장별, 두부유형별 위생실태를 파악하여 두부에 대한 미생물 규격의 설정 가능성을 검토하며, 가공단계별 총생균수와 대장균군을 분석하여 오염 원인을 규명코자 실시되었다. 시판중인 두부의 위생성은 동일유형이더라도 가공공장마다 차이가 있었고 동일공장의 시료 간에도 차이를 보였다. 총생균수가 <TEX>$1.0{\times}10^6CFU/g$</TEX> 이상을 보인 일부 포장두부에서는 관능적 부패 변질 현상이 관찰되었다. 총 148개 두부시료 중 총생균수와 대장균군이 각각 <TEX>$1.0{\times}10^5CFU/g$</TEX> 이하와 음성에 적합한 시료는 단순포장두부가 32.0%와 12.0%, 포장가열두부가 86.9%와 83.7%인 것으로 조사되었다. 이러한 가공공장에 따른 위생성 차이는 가열과 열처리사이의 공정인 응고, 압착, 성형, 1차냉각, 내포장공정에서 2차오염 정도의 차이에서 기인하는 것으로 생각되었다. 포장두부의 가공공정 중 미생물이 증가하여 각별한 관리가 요구되는 공정으로는 원료대두의 세척 침지와 마쇄, 응고 후 압착 성형, 1차냉각공정이었다. 따라서 보다 위생적인 두부를 가공하기 위해서는 이들 가공공정에서 사용되는 각종 설비나 작업도구, 성형포 및 작업자 등에 대한 세척 및 소독 강화가 절실하게 요구되었다. This study was conducted to investigate microbial distribution in the processing steps and to estimate quality index and shelf life of packaged Tofu (soybean curd). Sanitation and safety of Tofu were analysed in aspects of total viable counts (TVCs) and coliforms. Organoleptic deterioration was observed from some packaged Tofu when their TVCs were over <TEX>$10^6\;CFU/g$</TEX>. The controlled simply packaged Tofu and sterilized Tofu with TVCs of under <TEX>$10^5\;CFU/g$</TEX> were 32.0% and 86.9% of the total samples, respectively. Also, the controlled simply packaged Tofu and sterilized Tofu with negative coliforms were 12.0% and 83.7% of the total samples, respectively. TVCs and coliforms increased in some processing steps, which include washing and soaking of raw soybeans, and formation and 1st cooling of packaged Tofu. Increases of TVCs and coliforms in the washing and soaking step were due to contamination from the soaking tank and airborne bacteria, whereas increases of TVCs and coliforms in the grinding step were due to contaminations from the grinder, line and reserving tank. TVCs and coliforms increased in the formation and 1st cooling step of packaged Tofu due to contaminations from filter wools, trays, employee's hands, cooling water, formed products and filter wools.

MODELLING THE EFFECT OF TEMPERATURE AND CO2 ON MICROBIAL SPOILAGE OF CHILLED GILTHEAD SEABREAM FILLETS

ISHS IV International Symposium on Applications of Modelling as an Innovative Technology in the Agri-Food-Chain: Model-IT MODELLING THE EFFECT OF TEMPERATURE AND CO2 ON MICROBIAL SPOILAGE OF CHILLED GILTHEAD SEABREAM FILLETS

CURRENT STATUS OF PLANT PRODUCTS AS BOTANICAL PESTICIDES IN STORAGE PEST MANAGEMENT

ABSTRACT The increasing concern over the level of pesticide residues in food has encouraged researchers to look for alternatives of synthetic pesticides. Their indiscriminate use has led to the development of resistant strains of pests as well as different environmental and human health problems. Recently, in different parts of the world, attention has been paid towards exploitation of higher plant products as novel chemotherapeutants in plant protection. Because of non phytotoxicity, systemicity, easy biodegradability and stimulatory nature of host metabolism, plant products possess the potential in pest management. Used widely until the 1940’s, these natural pesticides were displaced by modern synthetic pesticides that at the time seemed cheaper, easier and long lasting. The popularity of botanical pesticides is once again increasing and some plant products are being used globally as green pesticides. The body of scientific literature documenting bioactivity of plant derivatives to different pests continues to expand, yet only a handful of botanicals are currently used in agriculture. Pyrethroids and neem products are well established commercially as botanical pesticides and recently some essential oils of higher plants have also been used as antimicrobials against storage pests because of their relatively safe status and wide acceptance by the consumers. Some of the volatile oils, which often contain the principal aromatic and flavouring components of herbs and spices, have been recommended as plant based antimicrobials to retard microbial contamination and reduction in spoilage of food commodities. Furthermore, some of the antimicrobial plant products also possess strong antioxidant activities which are favourable properties to combat free radical mediated organoleptic deterioration of plant commodities and enhancing their shelf life. In the context of agricultural pest management, botanical pesticides are best suited for use in organic food production in industrialized countries but can play a much greater role in the production and post harvest protection of food products in developing countries.

Monitoring the sensorial and microbiological quality of pasteurized white asparagus at different storage temperatures

AbstractChanges in sensory quality and proliferation of pathogenic and spoilage microorganisms in pasteurized white asparagus were measured as a function of storage temperature. The main sensorial attributes studied with regard to storage time were the general appearance of the product, turgidity and package swelling. There was a significant correlation between the deterioration in sensorial quality and microbial evolution, which was even more marked at higher temperatures. After 13 days at 4°C, 6 days at 10°C, 5 days at 20°C and 84 h at 30°C organoleptic deterioration and, consequently, the end of shelf life were detected. A significant growth of spoilage flora was observed, which might be responsible for the drop in pH levels during the final period of analysis (from 6.3 to 3.5–4 until 148 h). There was greater lactic acid bacteria (LAB) growth as the temperature and CO2 concentration increased, reaching a final concentration of approximately 108 CFU g−1 at all temperatures. We found no positive samples of Clostridium spp at 10 and 4°C. Among the species isolated at 20–30°C Clostridium septicum and in lower proportions Clostridium perfringens were encountered. The possible presence of Listeria monocytogenes was analyzed, but there were no positive samples in the final product. Pasteurized white asparagus maintains good organoleptic characteristics with a relatively long shelf‐life at low temperatures, which leads to an adequate acceptance among consumers. Copyright © 2006 Society of Chemical Industry

Staling white pan bread: fundamental causes.

Staling, as it is applied to bakery foods, is a generic term covering a number of changes that occur in the products during normal storage. Consumers judge staleness by direct perception, which provides a subjective estimate that represents an unconscious integration of many factors. This review will discuss the main components of staling: (1) physicochemical changes of bread and related products (firming and texture deterioration of crumb and loss of crispness of crust) and (2) flavor changes. Section I will cover current theories of changes of firming and textural changes. The starch component of flour is generally considered to be responsible for these staling reactions. Consequently, the physicochemical involvement of amylose, amylopectin in these reactions will be fully discussed and current evidence supporting these theories (rheological, chemical, X-rays) will be given. Interactions of starch and surface active agents and other complexing compounds will be presented in Section II. In Section III, contribution of minor flour components and bakery food ingredients will be evaluated. Section IV will focus on organoleptic deterioration of products, presenting flavor changes that were observed during staling bread. Section V will discuss structural changes of breads caused by enzymolysis during bread production and storage as related to staling. Following the theoretical section (Sections I to V), Section VI will focus on practical control of staling. This discussion will cover the following factors: formulation, surfactants, enzymes, storage, freezing, and packaging.

Staling of white pan bread: Fundamental causes∗

Staling, as it is applied to bakery foods, is a generic term covering a number of changes that occur in the products during normal storage. Consumers judge staleness by direct perception, which provides a subjective estimate that represents an unconscious integration of many factors. This review will discuss the main components of staling: (1) physicochemical changes of bread and related products (firming and texture deterioration of crumb and loss of crispness of crust) and (2) flavor changes. Section I will cover current theories of changes of firming and textural changes. The starch component of flour is generally considered to be responsible for these staling reactions. Consequently the physicochemical involvement of amylose, amylopectin in these reactions will be fully discussed and current evidence supporting these theories (rheological, chemical, X‐rays) will be given. Interactions of starch and surface active agents and other completing compounds will be presented in Section II. In Section III, contribution of minor flour components and bakery food ingredients will be evaluated. Section IV will focus on organoleptic deterioration of products, presenting flavor changes that were observed during staling bread. Section V will discuss structural changes of breads caused by enzymolysis during bread production and storage as related to staling. Following the theoretical sections (Sections I to V), Section VI will focus on practical control of staling. This discussion will cover the following factors: formulation, surfactants, enzymes, storage, freezing, and packaging.

Effect of Retail Sanitation on the Bacterial Load and Shelf Life of Beef

The influence of retail sanitation on the psychrotrophic bacterial load and subsequent shelf life of rib steaks was investigated under laboratory-simulated retail processing conditions. Steaks were fabricated employing extensively sanitized processing equipment (< 10 bacteria/cm2 of surface) or with highly contaminated equipment where bacterial counts approached 106/cm2. No significant differences were observed in the initial psychrotrophic bacterial load, bacterial growth rate or in the organoleptic deterioration of steaks processed under these extremes of retail sanitation. These results were confirmed with ground beef fabricated under similar extremes of grinding sanitation. Although the psychrotrophic bacterial load on steaks could not be related to the degree of retail processing sanitation, it was significantly correlated with the level of surface contamination on wholesale ribs. In addition, the extent of steak surface discoloration and overall retail appearance were significantly correlated to the psychrotrophic bacterial load.

ACCELERATED SHELF‐LIFE TESTING OF AN INTERMEDIATE MOISTURE FOOD IN AIR AND IN AN OXYGEN‐FREE ATMOSPHERE

ABSTRACTAn intermediate moisture food at water activity 0.85 was stored in air and an oxygen‐free atmosphere at 25, 35 and 45°C. Various modes of deterioration were studied including rancidity, nonenzymatic browning, vitamin C loss, and organoleptic panel evaluation. It was found that all modes of deterioration deviated from an Arrhenius relationship of log (rate) vs °K−1 when higher temperature data were projected to lower temperature. These projections underestimate the true shelf life which is of benefit to the processor. This deviation may be due to mechanism changes, but most likely is a result of the heterogeneity of the system. The major mode of organoleptic deterioration was related to browning. Lysine and vitamin C losses were also very rapid. A special low oxygen scavenger web film increased shelf life significantly.

Microbial Studies on Shelf Life of Cabbage and Coleslaw

The microbiology of a common commercial type of coleslaw was investigated with the objective of extending its shelf life at refrigerator temperature by delaying microbiological spoilage. Cabbage, its principal ingredient, had a total bacterial count of about 10/g. Microbial growth in cabbage was prevented by storage at 1 C but not at 10 C or above. In coleslaw, the cabbage flora died and was replaced by the flora of the cultured sour cream contained in the dressing. At 14 C, the total count increased and the coleslaw deteriorated organoleptically. At 7 C, bacterial growth was suppressed but organoleptic deterioration occurred as rapidly as at 14 C. Thus, the deterioration was caused primarily by the physiological breakdown of plant tissue rather than by microorganisms, as was the original premise.

COMPUTER‐AIDED PREDICTIONS OF FOOD STORAGE STABILITY: OXIDATIVE DETERIORATION OF A SHRIMP PRODUCT

ABSTRACT— A study was conducted on stability of a freeze‐dried shrimp bar packaged in various materials. The purpose of this study was to develop a method for predicting the storage stability of dry foods stored in semipermeable containers and deteriorating through oxidation of lipids. In the shrimp bar, organoleptic deterioration was correlated with absorption of oxygen and with loss of carotenoid pigment; these indices of oxidation were used for the study. Rates of oxidation were studied as a function of oxygen concentration and permeability characteristics of materials used to package the bars determined. A mathematical model for prediction of storage life of the product was formulated using the kinetic data for shrimp oxidation and the permeability data. An iteration procedure utilizing a high‐speed computer was used to solve the pertinent equations and to predict storage life. Predictions were compared with results of actual storage tests; those based upon pigment loss were better than those based upon changes in flavor score.

STORAGE DETERIORATION OF FREEZE‐DRIED AVOCADO PUREE AND GUACAMOLE

SUMMARY— The effect of storage temperature, time and atmosphere on the chemical and organo‐leptic characteristics of freeze‐dried avocado puree and guacamole was studied using Waldin, Lula and Booth‐8 varieties of avocado. Oxidation rates were slower at 21°C than at 38°% storage and nitrogen atmospheres reduced the peroxide formation. Significant differences existed in oxidation rates between avocado varieties and also between guacamole and avocado puree in some instances. A logarithmic relationship was found between peroxide values and storage time in air. Guacamole made with Lula avocados was unacceptable after 3 weeks of storage in air at 38°C. Samples stored in nitrogen at 38°C ware unacceptable at the end of 7 weeks. Samples stored in air at 21°Cwere acceptable after 12 weeks and those stored in nitrogen at 2l°C after 15 weeks. A commercial BHA antioxidant reduced the oxidation rate of Lula puree but did not increase shelf life in air storage at 38°C. Peroxide values were of no use in predicting acceptability, since organoleptic deterioration could occur without any peroxide increase.